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A method for measuring quality of life through subjective weighting of functional status
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A Method for Measuring Quality of Life Through Subjective Weighting of Functional Status Margaret G. Stineman, MD, Barbara Wechsler, MD, Richard Ross, MA, Greg Maislin, MS, MA ABSTRACT. Stineman MG, Wechsler B, Ross R, Maislin G. A method for measuring quality of life through subjective weighting of functional status. Arch Phys Med Rehabil 2003; 84 Suppl 2:S15-22. Objective: To apply a new tool to understand the quality of life (QOL) implications of patients’ functional status. Design: Results from the Features-Resource Trade-Off Game were used to form utility weights by ranking functional activities by the relative value of achieving independence in each activity compared with all other component activities. The utility weights were combined with patients’ actual levels of performance across the same activities to produce QOLweighted functional status scores and to form “value rulers” to order activities by perceived importance. Setting: Persons with severe disabilities living in the community and clinicians practicing in various rehabilitation disciplines. Participants: Two panels of 5 consumers with disabilities and 2 panels of 5 rehabilitation clinicians. Interventions: The 4 panels played the Features Resource Trade-Off Game by using the FIM™ instrument definitions. Main Outcome Measures: Utility weights for each of the 18 FIM items, QOL-weighted FIM scores, and value rulers. Results: All 4 panels valued the achievement of independence in cognitive and communication activities more than independence in physical activities. Consequently, the unweighted FIM scores of patients who have severe physical disabilities but relatively intact cognitive skills will underestimate QOL, while inflating QOL in those with low levels of independence in cognition and communication but higher physical function. Conclusion: Independence in some activities is more valued than in others; thus, 2 people with the same numeric functional status score could experience very different QOL. QOLweighted functional status scores translate objectively measured functional status into its subjective meaning. This new technology for measuring subjective function-related QOL has a variety of applications to clinical, educational, and research practices.
From the Department of Rehabilitation Medicine (Stineman, Wechsler, Ross); Leonard Davis Institute of Health Economics (Stineman); Clinical Epidemiology Unit of the Center for Clinical Epidemiology and Biostatistics (Stineman, Maislin); and Institute on Aging (Stineman), University of Pennsylvania, Philadelphia, PA. Supported by National Institutes of Health (grant nos. RO1-HD34101, RO1HD37234, T32-HD07425-09). The opinions and conclusions herein are not necessarily those of the sponsoring agencies. Presented in part at Quality of Life Measurement: Building an Agenda for the Future, November 16, 2001, Parsippany, NJ. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated. Correspondence to Margaret G. Stineman, MD, Dept of Rehabilitation Medicine, University of Pennsylvania, Ralston Penn Ctr, #101, 3615 Chestnut St, Philadelphia, PA 19104-2676. Reprints are not available. 0003-9993/03/8404-7581$30.00/0 doi:10.1053/apmr.2003.50242
Key Words: Outcome assessment (health care); Patientcentered care; Quality of life; Recovery of function; Rehabilitation. © 2003 by the American Congress of Rehabilitation Medicine HE ULTIMATE OBJECTIVE of functional assessment is T to discover how best to meet the needs of the patient from his/her own perspective and to enhance quality of life (QOL). 1
Calman2 defines QOL as the extent to which a person’s hopes are matched by experience. Experience defines life and shapes self-esteem. Hopes, presumably, determine the order by which an individual would choose to recover the ability to perform various activities after onset of disability if the recovery process were under full voluntary control. For instance, when a physical therapist scores a patient at FIM™ instrument3,4 level 3 in stair climbing, the patient experiences the need for moderate amounts of assistance.5 The objective state of requiring assistance to climb stairs says nothing about how the patient views being in that state. The value of being in that state is determined by the personal feelings engendered and by the individual’s desires and needs to interact with the specific physical and social environments in which they live. A person who lives in a house with no bathroom on the first floor may value being able to climb stairs relatively more than a second person who lives in an efficiency apartment with elevator access. The intensity of feelings engendered by being in one state of dependency, as opposed to another, will motivate the desire to recover independence in one activity over another. Moreover, the perceived value of being in one state as opposed to a different state of function, may depend on who is establishing the values. Kane et al,6 using a simple rating task, found that residents in a sheltered housing project, in comparison to their professional caregivers, expressed differences in the degree to which they believed limitations in 13 activity of daily living (ADL) and instrumental ADL tasks would be debilitating. Although the objective measurement of functional status is essential to defining a patient’s degree of disability, subjective expressions are required to translate that objective measurement into the actual QOL experienced.7 An understanding of the motivations that drive recovery has therapeutic implications because it highlights the functional achievements that would most enhance QOL. Adding clarity to this issue, Dijkers8 established a taxonomy for QOL instruments that distinguishes between objective and subjective measures. In that taxonomy, objective measures focus on QOL as a “set of characteristics of persons and their environments that can be measured independently from their subjective reactions.”8 The objective approach is relevant to policy and evaluative research that must compare the QOL outcomes of various rehabilitation programs and interventions from the view of “society as a whole” by using standard metrics. In contrast, the subjective approach takes a different view that only the person or people involved with a particular health or functional state can “judge the quality of his/her life and that, therefore, the only approach to measuring QoL is to get the report from him/her.”8(p287) The Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
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MEASURING QUALITY OF LIFE BY SUBJECTIVE WEIGHTINGS, Stineman
subjective approach is relevant to understanding how expectations and values differ among people and the psychologic traits that explain differences between them. It is also necessary when addressing disparities between the objective world and subjective experiences. We previously established a method of utility assessment,9 referred to as the Features-Resource Trade-Off Game,10 that can express the strength of people’s preferences for alternative states of functioning. The game differs from classic utility methodologies, such as the standard reference gamble, time trade-off, or visual analog scale.9,11,12 By requiring participants to imagine simultaneous trades among multiple traits, it forces players to make explicit choices of imagined increased function among activities as diverse as eating and remembering. Recognizing the importance of developing ways to quantify subjectively QOL, we present a methodology that uses results from the game to generate a relative “utility weight” for each of the various activities rated in a multi-item functional status measure. The FIM instrument3,4 was selected as an example multi-item measure because of its widespread use in the United States and in other nations. Utility weights in this application express people’s relative preference for achieving greater independence in 1 FIM activity as opposed to the remaining 17. We then show how these utility weights can be combined with patients’ actual levels of performance on each of the same functional activities to produce QOL-weighted FIM scores. QOL-weighted FIM scores convert patients’ actual functional status scores from each separate activity into a single index number that expresses the overall implications of their measured status to QOL. The QOL-weighted FIM is an expression of function-related QOL. Because functional limitations typically result from medical illness, function-related QOL closely aligns with health-related QOL.13 QOL-weighted functional status scores will be most meaningful when presented alongside the patient’s objectively measured functional performances across the same set of activities. METHODS The FIM instrument3,4 was the objective measure used to show how to calculate QOL-weighted functional status. The methods illustrated are intended to be appropriate for use with any ordinal functional status measure that includes multiple activities. The FIM quantifies patients’ abilities to perform 6 ADLs (items A–F); 2 sphincter management functions (items G, H); 5 mobility activities (items I–M); and 5 social, cognitive, and communication functions (items N–R). Patients’ performance scores on each of the 18 items are combined in various ways, yielding total scores or profiles that objectively quantify the degree of assistance required by the person when performing activities. Total scores are formed by summing14 or otherwise combining15 the performances on some or on all of the 18 functional activities to produce single values. A profile, as distinct from a score, consists of the separately expressed performance levels on each of the 18 individual items. The Features-Resource Trade-Off Game The relative value of spending “resources” on alternative “features” is established through a trade-off process adopted from economic theories of scarce resources and marginal rates of substitution.16 Stineman et al10 previously showed the resulting preference stages formed by 4 groups of players based on the FIM. The game provides a means to weigh the value of various features relative to others by measuring where people would place set quantities of some type of resource. Here, each FIM item is a feature, and the resource is the number of independence levels available to be spent at any point in the Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
game process. When used to approximate QOL, the game documents a pattern of functional recovery for a hypothetical individual through an ordered number of preference stages. It is hypothesized that the QOL of the individual and of his/her family improves with each increase and that the life implication of that improvement will depend on the activities recovered. Game moves are based on the progress of a hypothetical individual living in an imaginary place in which all functional goals are equally accessible and attainable, whether or not effective therapy currently exists. Values, not physiologic feasibility of recovery, are being established. The following definitions are intended to clarify the process. Definitions The Features-Resource Trade-Off Game. The FeaturesResource Trade-Off Game is a process for identifying levels of functioning across a series of functional status activities intended to identify optimal patterns of recovery as perceived by an individual or by a group. The resulting profiles are referred to as “preference stages,” which yield utility weights for each activity. The game is played by 3, 5, or 7 people (optimally, an odd number) on a game board by moving “independence-level” pointers to show how the group believes it would want to recover function if patterns of recovery were under volitional control. Features. Features are the various activities in the functional status measure that are being ranked by value or recovery preference. Any multi-item functional status measure can be used to play the game. In the example being provided, each FIM item (eg, eating, grooming, bathing) represents a feature. Resources. Resources are the amount of independence that can be “spent” on alternative “features.” In the example provided, 1 independence level is 1 improvement point in 1 FIM activity. Preference stage. Preference stage is an optimum pattern of recovery as perceived by an individual or group assuming or imagining initial total dependence on others for the performance of each of a specified set of activities. It also assumes people are allowed to spend a limited number of independence levels. Utility weight. The utility weight is the relative value attached to one activity as opposed to all other activities in the set of features used to play the game as calculated from a preference stage. The guiding principle. The guiding principle is the vantage point, provided to the players, from which independence points are to be spent, which defines the overarching goals of recovery. Overarching goals might be “to return home” or “to return to work.” Vantage points can be from the person with disabilities, the person’s caregiver, or the payer of services. Any number of different principles could be formulated as a guide to building preference stages. Instructions for Playing the Game Players must be given verbal and written definitions of each of the functional status activities for which the game is being played. They were encouraged to seek clarifications of any item’s definition during the game. The definitions used here were those in the Uniform Data System for Medical Rehabilitation.4 Each of the 18 FIM items were also discussed. Players further received a written copy of the guiding principle for making moves. The principle used to obtain the data presented here, as adapted from the overarching goal of the independent living movement, was: “Make moves in a way that maximizes self-direction, minimizes the restrictiveness of any given envi-
MEASURING QUALITY OF LIFE BY SUBJECTIVE WEIGHTINGS, Stineman
ronment, and maximizes personal and economic freedom.”17 The vantage point was of the person with disabilities. All players were given a copy of a game board to follow the hypothetical individual’s progress. The board listed the 18 FIM activities along the left-hand side and the 7 performance levels across the top. At the beginning of the game, players were asked to imagine that they required total assistance in all activities. The board, at the start, had the column labeled “total assistance” filled with the independence-level pointers next to each activity signifying stage 1. These pointers were subsequently moved forward by the players to create the preference stages. To form higher stages, the independence levels of the FIM were spent by the players to advance from 1 (total dependence) to 7 (complete independence) in specific activities during the course of the game. To advance from one preference stage to the next, players were allowed to spend 18 independence levels in any way they saw fit, choosing to advance multiple levels for single activities or fewer levels for multiple activities. The average performance level of activities at any stage, by definition, corresponds to the stage number (ie, the performance levels across the 18 activities for stage 2 average 2, for stage 3 average 3, and so forth). The game consists of N⫺2 rounds, where N equals the number of performance levels defined for the activities of the assessment instrument being used. The number of activities defines the number of moves that make up a round. For the FIM example, there were 7⫺2⫽5 rounds with 18 moves for each round. Each round consists of 2 methods of advancing recovery: “free movement” and “zero-sum exchange” designated as step A and step B. Step A: free movement. The first player makes 1 move forward for the most valued activity. The players take turns until the number of moves equals the number of activities in the instrument. In this example, there were 18 free movements. No comments about the moves are allowed. This defines a preliminary preference stage. Step B: zero-sum exchange. Players are asked to reflect on the implications of the preliminary preference stage shown by the board configuration at the conclusion of the free-movement step. Each player is given the opportunity to change the board so that an activity he/she feels is more valuable is pushed forward at the expense of 1 retrograde move for another lessvalued activity. After the exchange, the player provides a rationale for it. The other players are offered an opportunity to present briefly the pros and cons of the exchange. The exchange is then put to a vote. If not agreed to by the majority, the board is returned to its earlier configuration. The configuration, after all players have offered 1 zero-sum exchange, defines the final preference stage. In this example, 5 players participated, so there were 5 zero-sum exchanges for each stage. Steps A and B are repeated to form the remaining stages. Before formulating a new stage, the scenario is reset by asking the players to imagine that they are at this new functional level. A simplified version of the game for an individual player, more appropriate to clinical practice, is described in the discussion. Use of Game Results Game results were obtained from two 5-person panels of rehabilitation clinicians and two 5-person panels of people with disabilities (consumers) living in the Philadelphia and Houston areas. Most consumers were dependent on wheelchairs as their primary means of mobility and several communicated through an assistant. All were extremely active, and several were employed. Consumers were selected to represent a wide variety of physically disabling conditions, including cerebral palsy, spinal
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muscular atrophy, tetraplegia, rheumatoid arthritis, and lowerlimb amputation. The clinician panels were formulated such that each panel included individuals with a wide range of clinical disciplines and experiences in diverse clinical settings. Disciplines were neuropsychology, occupational therapy, physiatry, physical therapy, psychology, rehabilitation nursing, speech pathology, and rehabilitation counseling. These panels were selected because we believed that their experiences placed them in a good position to understand the FIM activities most essential to independent living. The results were a set of 5 preference stages from each panel (published previously).10 These stages are used to show the following. 1. Calculation of utility weights for measuring the relative value of increasing independence in each functional activity compared with all other activities in a multiattribute instrument. 2. Use of utility weights to distinguish different goal preferences among groups of people with different life circumstances. 3. Development of value rulers from utility weights and their use in establishing the most meaningful patient goals. 4. Calculation of QOL-weighted functional status measures by combining utility weights with patients’ observed performances. 5. Interpretation of QOL-weighted scores. Three sets of FIM discharge scores from a program evaluation database that contained no personally identifying information were used to show the calculation and interpretation of QOLweighted functional status scores. Establishing item utility weights from preference stages. At the conclusion of the game, the utility weight for each activity is calculated by combining the cumulative FIM scores for stages 2 through 6. Stage 1 is total dependence in all 18 activities. Stage 7 is complete independence in all 18 activities. (Because there is no variability in level across the activities in these 2 latter stages, they are not included in the utility weight calculations.) This is shown later. Figure 1 shows preference stages established by the Philadelphia panel of consumers with physical disabilities. The 18 FIM activities are abbreviated around the periphery and concentric circles intersect the slices at points corresponding to the FIM performance levels. The innermost circle represents level 1 (total assistance), the intermediate circles represent levels 2 through 6, and the outer circle represents level 7 (complete independence). The shaded areas demarcate the FIM performance levels selected by the Philadelphia consumers10 for each activity at each of the 5 intermediate stages. A utility weight for a particular item, relative to the others, is determined by counting up all the shaded areas for a given activity at each stage and then adding the counts. For example, analyzing figure 1, the utility weight for eating as addressed by the Philadelphia consumers is 1⫹4⫹5⫹5⫹6⫽21. The utility weights for each activity and for each of the 4 panels were calculated from their preference stages in a similar fashion. Developing value rulers. Value rulers are graphic displays of utility weights ordered by magnitude that enable rapid comparisons of the preference similarities and differences between individuals or groups. Calculating QOL-weighted scores from item utility weights. QOL-weighted functional status scores are calculated by combining utility weights with patients’ objectively observed levels of performance in the same activities (unweighted scores). To calculate a QOL-weighted score for a patient, first multiply Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
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MEASURING QUALITY OF LIFE BY SUBJECTIVE WEIGHTINGS, Stineman
Fig 1. Philadelphia Consumer Panel. Shown is an example set of preference stages for Philadelphia consumers. Abbreviations: Ea, eating; Gr, grooming; Ba, bathing; DU, dressing upper body; DL, dressing lower body; To, toileting; Bl, bladder management; Bo, bowel management; ChT, chair transfer; Tot, toilet transfer; TuT, tub transfer; WC, walk wheelchair; St, stair climbing; Co, comprehension; Ex, expression; Si, social interaction; Ps, problem solving; Me, memory.
utility weights by his/her corresponding unweighted score for each activity. Sum the products. Divide by the sum of the value weights to obtain the average value weight. The sum of the weights for the FIM is 360. To rescale the QOL-weighted score so that it is comparable to the unweighted score, multiply the average value weight by the number of features in the scale (18 for the FIM). To estimate congruity of QOL-weighted and unweighted functional status scores, subtract the unweighted score from the QOL-weighted score. If the difference is positive, the patient is functioning at greater levels of independence Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
in more valued activities. If the difference is negative, the patient is functioning at greater independence in less valued activities. When interpreting the utility weight, or QOLweighted scores, and the value rulers derived from them, it is essential to recognize that as value-laden subjective metrics the numeric quantities are most relevant to the individuals who played the game. The particular game results presented here are provided as an illustration of techniques only and are not intended to be used in drawing conclusions about universal values.
MEASURING QUALITY OF LIFE BY SUBJECTIVE WEIGHTINGS, Stineman
Fig 2. Value rulers specific to each of the 4 groups. Abbreviations: PCO, Philadelphia consumers; PCL, Philadelphia clinicians; HCO, Houston consumers; HCL, Houston clinicians; a, eating; b, grooming; c, bathing; d, dressing upper; e, dressing lower; f, toileting; g, bladder; h, bowel; i, chair transfer; j, toilet transfer; k, tub transfer; l, walk/wheelchair; m, stairs; n, comprehension; o, expression; p, social interaction; q, problem solving; r, memory.
RESULTS
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Fig 3. A study of utility weight variability for the 18 FIM activities across the 4 groups. Abbreviations: see fig 2.
QOL-Weighted Functional Status Table 1 shows the actual FIM performance levels on each of the 18 FIM items for patients A, B, and C used to calculate QOL-weighted and unweighted FIM scores. The QOLweighted total FIM scores of patients A, B, and C are compared with their unweighted total FIM scores in table 2. That table shows the range in scores for each patient as determined from
Utility Weights and Value Rulers Item utility weights are ordered along value rulers specific to each panel (fig 2). Utility was consistently highest in cognitive and communication activities. Utility was consistently lowest for tub or shower transfer and stair climbing. Utility Weight Variability Across the Panels Variability in item utilities across all 4 panels is shown in figure 3. Distributions of utilities (y axis) are shown for each activity (x axis). When fewer than 4 utility values are displayed for an activity, it means that 2 or more of the panels have assigned that activity the same value. Utilities for eating, comprehension, and expression varied little, whereas utilities for bathing and grooming vary considerably. The achievement of independent communication and cognitive functioning was seen by all 4 panels as the most valuable outcome, assuming initial dependence in all activities. In figure 4, average item utilities from the 2 consumer panels are plotted on the x axis and average utilities from the 2 clinician panels on the y axis. The 45° line represents the position at which the clinician and consumer panel utilities are equal for an activity. Item m (stair climbing) was of an equally low utility for both types of panels. Although both the clinicians and consumers valued memory, problem solving, and social interaction highly, the utility of these items was even greater for the clinician than for the consumer panels. This type of graphic display can show how the functional goals set by 2 individuals (eg, a patient and family member) or by 2 groups of individuals (eg, patients and clinicians) would differ.
Fig 4. Comparison of utility weights comparing consumers and clinicians. See fig 2.
Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
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MEASURING QUALITY OF LIFE BY SUBJECTIVE WEIGHTINGS, Stineman Table 1: Actual Performance Levels for 3 Patients Actual FIM Performance
Patient A
Patient B
Patient C
Eating Grooming Bathing Upper dressing Lower dressing Toileting Bladder Bowel Transfer bed Transfer toilet Transfer tub Locomotion Stairs Comprehension Expression Social interaction Memory Summed total
1 1 1 1 1 1 6 1 1 1 1 5 1 7 7 7 7 57
6 2 2 2 1 1 1 1 1 1 1 1 1 6 4 6 2 42
7 7 7 7 7 7 7 7 7 7 7 7 7 3 2 2 1 100
the utility weights of the different panels. These ranges are followed by the panel average QOL-weighted score for each patient and by the unweighted total FIM score. The last column of table 2 is the difference between the average QOL-weighted FIM scores and the unweighted FIM scores. Because patients A and B were functioning more independently in FIM activities that were perceived by the panels to be of relatively high value compared with the other activities, their QOL-weighted scores were higher than their unweighted FIM scores, producing positive differences. Conversely, because patient C was functioning more independently in activities with low value than in activities with high value, her QOL-weighted score was lower than her unweighted FIM score, producing a negative difference. This implies that the unweighted FIM score would tend to underestimate patient A and B’s function-related QOL, but overestimate patient C’s function-related QOL, at least from the vantage point of the panels of individuals who played the game in this example. DISCUSSION The game can be applied to elicit preferences for improvement in specific activities included in a functional status measure, thereby establishing the relative value or utility of being able to perform each component activity compared with the other activities. Utility weights are formed through the game process by measuring the degree to which groups of people would be willing to exchange the achievement of greater independence in 1 activity for lesser independence in a different activity. Those utility weights, in turn, can form value rulers for goal setting, or, when combined with patients’ objectively measured functional status, form QOL-weighted scores. We recognize that many aspects of life not considered as health or function, such as income, quality of environment, or freedom, can affect QOL.13 Consequently, we see QOL-weighted functional status scores as a metric for estimating only the subjective contribution of function to QOL. Function-related QOL is closely related to other aspects of life that affect well-being and, in fact, is likely influenced by those factors. For example, the value of being able to walk up stairs versus dress independently will depend on the architecture of one’s living space, who is available to provide help, and the personal implications Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
of being able to perform those activities. The methodology, as applied here to the FIM, produces QOL-weighted FIM scores. The QOL FIM is a single numeric index that translates patients’ objectively measured performance levels on each of the 18 component activities of the instrument into a single metric. That metric, along with value rulers, has many clinical, educational, research, and policy applications. The weights used in the QOL translation of the 3 sample patient FIM discharge scores were aggregated from the 4 consumer and clinician panel games. Thus, the resulting QOLweighted FIM scores represent the subjective points of view of the 20 panel members, rather than of the patients. Aggregated utility weights are appropriate to program evaluations or to continuous quality improvement. When estimating changes in QOL at the level of treatment populations, it is necessary to incorporate standard values as derived from the consensus of many people. In these applications, QOL-weighted scores established through utility weights from panel judgments are appropriate to differentiate between groups of people with better or worse function-related QOL. Subtracting rehabilitation admission QOL-weighted scores from discharge QOLweighted scores provides an estimate of the treatment population’s changes in function-related QOL, allowing that small increases in independence in the performance of a set of highly valued activities might represent a more desirable outcome than greater improvement in less valued activities. When interpreting QOL-weighted scores, it is essential to recognize that the implications depend on whose weightings were applied. We would discourage the reader from drawing any conclusions of generalizability regarding the particular utility weights used in this example. Had the 3 individuals whose FIM values were used to calculate the QOL-weighted scores provided their own game results, the resulting utility weights would have very different implications and, thus, applications. The resulting value rulers and person-specific QOL-weighted scores would reflect each persons’ subjective reaction to his/her function. Utility weights could now highlight the functional achievements the patient would most value. If a patient’s value ruler at admission to rehabilitation were to indicate that he/she most desires independence in bladder management, that would justify the spending of more resources toward meeting that goal. If the patient’s net change in QOL units is greater than his/her unweighted functional gain, then recovery occurred in areas that he/she most valued. Unweighted functional gain may over- or underestimate how individual patients value their rehabilitation outcomes. Therapists observing patients playing the game might gain a greater appreciation of their motivations and values. The game process could facilitate communication and education by forming an empathetic linkage with patients. People protect themselves from the negativity of others by erecting what Nathanson18 has called an empathic wall. Clinicians may tune out their patients’ reactions to disabilities, obscuring knowlTable 2: Comparing Objectively Measured FIM Performance to QOL Translations Range in QOL-Weighted QOL-Weighted QOL-Weighted FIM Across FIM Averaged Unweighted FIM⫺Unweighted Groups Across Groups FIM FIM (difference)
Patient A Patient B Patient C
69.7–77.0 48.6–53.0 83.6–88.8
73.3 50.6 86.2
57.0 42.0 100.0
⫹16.4 ⫹8.7 ⫺13.7
MEASURING QUALITY OF LIFE BY SUBJECTIVE WEIGHTINGS, Stineman
edge about the most troubling aspects of restrictions imposed by them. The process of playing the game cuts away the empathic wall, through guided communication and interaction about the therapeutic process and the patient’s current and desired states of functioning. This paves the way for communicating in difficult areas and for formulating the most relevant therapeutic approaches, through a participatory process that encourages the patient to contribute novel ideas to his/her own treatment planning.19 To be practical as a clinical tool, the group version of the game needs to be simplified and adopted to the individual. The Features-Research Trade-Off Game might be abbreviated for application to clinical practice in a number of ways. A simplified approach is illustrated—again, using the FIM. In this approach, the patient plays the game under clinician guidance. A guiding principle is provided, tailored to the process of goal setting and to the patients’ overarching life objectives. The therapist explains to the patient that the game process is a way to help set goals and explore approaches to therapy that will be most meaningful. The therapist invites the patient to imagine total dependence in all FIM activities. He/she is then encouraged to make 18 moves, as described in step A for the group version in the methods section. The 18 moves define preference stage 2. The clinician asks the patient to imagine that he/she is now functioning at that new level. He/she is encouraged to make another 18 moves, creating stage 3. This continues through formulation of the remaining preference stages, 4, 5, and 6. As the patient’s preference stages begin to meet and exceed his/her current status, the clinician encourages the patient to share the logic of his/her choices, focusing on contexts, such as anticipated family support, architectural qualities of the home, or goals such as returning home or to work. Individual value rulers and QOL-weighted scores can be created from the game results, as described for the group process. Step B is not performed in the individual version. Estimating population-level QOL is becoming increasingly important for setting health care policies in the United States and worldwide.20 Health policy decisions require choices about resource allocation across diseases and disability subgroups at considerable costs.21 These choices depend on measures that enable comparison of very different treatment approaches. Policy analysts might want to apply QOL-weighted functional status scores across large samples of patients. Such analyses applied to diverse groups of people require a common yardstick. It is conceivable that repeated application of the group version of the game could produce utility weights that are broadly applicable across many types and severities of impairment and sociodemographic subgroups. Yet, if different people have widely different preferences, the aggregation of utility weights will be inappropriate. With respect to variation, among the 4 panels studied, the utility of certain activities appeared stable, whereas others were more variable. This supports the feasibility of developing population utility weights for certain subsets of activities. Aggregation of utility weights for the purposes of public policy making would be open to serious objections if it resulted in penalizing certain individuals whose legitimate needs were not recognized.22 Additional research is needed to make conclusions about how different groups of people value achievements in various functional domains. Utility weights provide the means to explore differences in preferences between various rehabilitation stakeholders, for example, between patients and family members, men and women, paraplegics and tetraplegics, older people and younger people, those of different cultural heritages, or any other defined groups of individuals. The examples provided in this article compared utilities established by rehabilitation clini-
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cians with those established by consumers with disabilities (figs 3, 4), showing both similarities and differences in the values among the groups studied. Measures of QOL-weighted function might also be applied to clinical trials when there is a need to address how an intervention has changed functionrelated QOL. This would require the development of utility weights by groups drawn from the same population as that being enrolled in the trial. Life experience depends on a person’s potential to integrate self with surrounding physical and social environments.23,24 Because surrounding environments and life contexts differ among people, the value of being able to perform a specific activity may vary across different individuals and groups. An unweighted score defines a functional state objectively across all people. Once QOL-weighted, the score becomes qualitative in nature, and its numeric value will depend on whose utility weights were applied. Although our illustrations were for the FIM instrument, the development of utility weights might be explored by using any measure of health status, function, or participation, with multiple items and ordered categories. Each domain of health and disability has many components with potential bearing on QOL. To understand the implications of disability, each domain is optimally measured both objectively and subjectively.7 CONCLUSION QOL-weighted functional status scoring is in its infancy. Clinicians, educators, researchers, and policymakers can use utility weights, value rulers, and QOL-weighted functional status scores to measure what matters: what people value about their functional abilities and how those values affect QOL. Patients’ unweighted functional status performance scores provide objective information about activity limitations.24 The QOL translation of those scores expresses the perceived meaning of those limitations. Objective knowledge about a patient’s actual performance and the subjectively experienced meaning of that performance are equally important when establishing therapeutic goals and evaluating rehabilitation outcomes. Value weights obtained from individuals or groups can estimate the degree to which patients’ achievements are in accordance with their own, their families’, or their clinicians’ hopes for recovery. Finally, this technology enhances the potential to involve patients in helping to direct the objectives of their own rehabilitation programs. Through the experience of playing the game, policymakers, clinicians, researchers, and patients can better understand the therapeutic process and its relevance. References 1. Batavia AI. Assessing the function of functional assessment: a consumer perspective. Disabil Rehabil 1992;14:156-60. 2. Calman KC. Quality of life in cancer patients—an hypothesis. J Med Ethics 1984;10:124-7. 3. Hamilton BB, Granger CV, Sherwin FS, Zielezney M, Tashman JS. A uniform data system for medical rehabilitation. In: Fuhrer MJ, editor. Rehabilitation outcomes: analysis and measurement. Baltimore: PH Brookes; 1987. p 137-47. 4. Uniform Data System for Medical Rehabilitation. Guide for the Uniform Data Set for Medical Rehabilitation (Adult FIM), version 4.0. Buffalo (NY): Research Foundation, State Univ New York; 1994. 5. Bunch WH, Dvonch VM. The “value” of Functional Independence Measure scores. Am J Phys Med Rehabil 1994;73:40-3. 6. Kane RL, Rockwood T, Finch M, Philp I. Consumer and professional ratings of the importance of functional status components. Health Care Fin Rev 1977;19(2):11-22. 7. Testa MA, Simonson DC. Assessment of quality-of-life outcomes. N Engl J Med 1996;334:835-40. Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
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8. Dijkers M. Measuring quality of life: methodological issues. Am J Phys Med Rehabil 1999;78:286-300. 9. Torrance GW. Utility approach to measuring health-related quality of life. J Chronic Dis 1987;40:593-600. 10. Stineman MG, Maislin G, Nosek MA, Fiedler RC, Granger CV. Comparing consumer and clinician values for alternative functional states: application of a new feature-resource trade-off consensus building tool. Arch Phys Med Rehabil 1998;79:1522-9. 11. Lipscomb J. Value preferences for health: meaning, measurement, and use in program evaluation. In: Kane RL, Kane RA, editors. Values and long term care. Lexington (MA): DC Heath; 1982. p 27-67. 12. Sox HC, Blatt MA, Higgins MC, Marton KI. Medical decision making. Boston: Butterworth; 1988. 13. Guyatt GH, Feeny DH, Patrick DL. Measuring health-related quality of life. Ann Intern Med 1993;118:622-9. 14. Stineman MG, Shea JA, Jette A, et al. The Functional Independence Measure: tests of scaling assumptions, structure, and reliability across 20 diverse impairment categories. Arch Phys Med Rehabil 1996;77:1101-8. 15. Linacre JM, Heinemann AW, Wright BD, Granger CV, Hamilton BB. The structure and stability of the Functional Independence Measure. Arch Phys Med Rehabil 1994;75:127-32.
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16. Samuelson PA. Foundations of economic analysis. Cambridge: Harvard Univ Pr; 1947. ch V. 17. Frieden L, Richards L, Cole J, Bailey O. ILRU source book: a technical assistance manual on independent living. Houston: The Institute for Rehabilitation and Research; 1979. 18. Nathanson DL. Shame and pride: affect, sex, and the birth of the self. New York: Norton; 1992. 19. Ozer MN. Patient participation in the management of stroke rehabilitation. Top Stroke Rehabil 1999;6(1):43-59. 20. Burstrom K, Johannesson M, Diderichsen F. Health-related quality of life by disease and socio-economic group in the general population in Sweden. Health Policy 2001;55(1):51-69. 21. Guyatt GH, Naylor CD, Juniper E, Heyland DK, Jaeschke R, Cook DJ. Users’ guides to the medical literature. XII. How to use articles about health-related quality of life. Evidence-Based Medicine Working Group. JAMA 1997;277:1232-7. 22. Leplege A, Hunt S. The problem of quality of life in medicine. JAMA 1997;278:47-50. 23. Stineman MG. Defining the population, treatments, and outcomes of interest: reconciling the rules of biology with meaningfulness. Am J Phys Med Rehabil 2001;80:147-59. 24. World Health Organization. ICF: international classification of functioning, disability and health. Geneva: WHO; 2001.
A Method for Measuring Quality of Life Through Subjective Weighting of Functional Status Margaret G. Stineman, MD, Barbara Wechsler, MD, Richard Ross, MA, Greg Maislin, MS, MA ABSTRACT. Stineman MG, Wechsler B, Ross R, Maislin G. A method for measuring quality of life through subjective weighting of functional status. Arch Phys Med Rehabil 2003; 84 Suppl 2:S15-22. Objective: To apply a new tool to understand the quality of life (QOL) implications of patients’ functional status. Design: Results from the Features-Resource Trade-Off Game were used to form utility weights by ranking functional activities by the relative value of achieving independence in each activity compared with all other component activities. The utility weights were combined with patients’ actual levels of performance across the same activities to produce QOLweighted functional status scores and to form “value rulers” to order activities by perceived importance. Setting: Persons with severe disabilities living in the community and clinicians practicing in various rehabilitation disciplines. Participants: Two panels of 5 consumers with disabilities and 2 panels of 5 rehabilitation clinicians. Interventions: The 4 panels played the Features Resource Trade-Off Game by using the FIM™ instrument definitions. Main Outcome Measures: Utility weights for each of the 18 FIM items, QOL-weighted FIM scores, and value rulers. Results: All 4 panels valued the achievement of independence in cognitive and communication activities more than independence in physical activities. Consequently, the unweighted FIM scores of patients who have severe physical disabilities but relatively intact cognitive skills will underestimate QOL, while inflating QOL in those with low levels of independence in cognition and communication but higher physical function. Conclusion: Independence in some activities is more valued than in others; thus, 2 people with the same numeric functional status score could experience very different QOL. QOLweighted functional status scores translate objectively measured functional status into its subjective meaning. This new technology for measuring subjective function-related QOL has a variety of applications to clinical, educational, and research practices.
From the Department of Rehabilitation Medicine (Stineman, Wechsler, Ross); Leonard Davis Institute of Health Economics (Stineman); Clinical Epidemiology Unit of the Center for Clinical Epidemiology and Biostatistics (Stineman, Maislin); and Institute on Aging (Stineman), University of Pennsylvania, Philadelphia, PA. Supported by National Institutes of Health (grant nos. RO1-HD34101, RO1HD37234, T32-HD07425-09). The opinions and conclusions herein are not necessarily those of the sponsoring agencies. Presented in part at Quality of Life Measurement: Building an Agenda for the Future, November 16, 2001, Parsippany, NJ. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated. Correspondence to Margaret G. Stineman, MD, Dept of Rehabilitation Medicine, University of Pennsylvania, Ralston Penn Ctr, #101, 3615 Chestnut St, Philadelphia, PA 19104-2676. Reprints are not available. 0003-9993/03/8404-7581$30.00/0 doi:10.1053/apmr.2003.50242
Key Words: Outcome assessment (health care); Patientcentered care; Quality of life; Recovery of function; Rehabilitation. © 2003 by the American Congress of Rehabilitation Medicine HE ULTIMATE OBJECTIVE of functional assessment is T to discover how best to meet the needs of the patient from his/her own perspective and to enhance quality of life (QOL). 1
Calman2 defines QOL as the extent to which a person’s hopes are matched by experience. Experience defines life and shapes self-esteem. Hopes, presumably, determine the order by which an individual would choose to recover the ability to perform various activities after onset of disability if the recovery process were under full voluntary control. For instance, when a physical therapist scores a patient at FIM™ instrument3,4 level 3 in stair climbing, the patient experiences the need for moderate amounts of assistance.5 The objective state of requiring assistance to climb stairs says nothing about how the patient views being in that state. The value of being in that state is determined by the personal feelings engendered and by the individual’s desires and needs to interact with the specific physical and social environments in which they live. A person who lives in a house with no bathroom on the first floor may value being able to climb stairs relatively more than a second person who lives in an efficiency apartment with elevator access. The intensity of feelings engendered by being in one state of dependency, as opposed to another, will motivate the desire to recover independence in one activity over another. Moreover, the perceived value of being in one state as opposed to a different state of function, may depend on who is establishing the values. Kane et al,6 using a simple rating task, found that residents in a sheltered housing project, in comparison to their professional caregivers, expressed differences in the degree to which they believed limitations in 13 activity of daily living (ADL) and instrumental ADL tasks would be debilitating. Although the objective measurement of functional status is essential to defining a patient’s degree of disability, subjective expressions are required to translate that objective measurement into the actual QOL experienced.7 An understanding of the motivations that drive recovery has therapeutic implications because it highlights the functional achievements that would most enhance QOL. Adding clarity to this issue, Dijkers8 established a taxonomy for QOL instruments that distinguishes between objective and subjective measures. In that taxonomy, objective measures focus on QOL as a “set of characteristics of persons and their environments that can be measured independently from their subjective reactions.”8 The objective approach is relevant to policy and evaluative research that must compare the QOL outcomes of various rehabilitation programs and interventions from the view of “society as a whole” by using standard metrics. In contrast, the subjective approach takes a different view that only the person or people involved with a particular health or functional state can “judge the quality of his/her life and that, therefore, the only approach to measuring QoL is to get the report from him/her.”8(p287) The Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
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subjective approach is relevant to understanding how expectations and values differ among people and the psychologic traits that explain differences between them. It is also necessary when addressing disparities between the objective world and subjective experiences. We previously established a method of utility assessment,9 referred to as the Features-Resource Trade-Off Game,10 that can express the strength of people’s preferences for alternative states of functioning. The game differs from classic utility methodologies, such as the standard reference gamble, time trade-off, or visual analog scale.9,11,12 By requiring participants to imagine simultaneous trades among multiple traits, it forces players to make explicit choices of imagined increased function among activities as diverse as eating and remembering. Recognizing the importance of developing ways to quantify subjectively QOL, we present a methodology that uses results from the game to generate a relative “utility weight” for each of the various activities rated in a multi-item functional status measure. The FIM instrument3,4 was selected as an example multi-item measure because of its widespread use in the United States and in other nations. Utility weights in this application express people’s relative preference for achieving greater independence in 1 FIM activity as opposed to the remaining 17. We then show how these utility weights can be combined with patients’ actual levels of performance on each of the same functional activities to produce QOL-weighted FIM scores. QOL-weighted FIM scores convert patients’ actual functional status scores from each separate activity into a single index number that expresses the overall implications of their measured status to QOL. The QOL-weighted FIM is an expression of function-related QOL. Because functional limitations typically result from medical illness, function-related QOL closely aligns with health-related QOL.13 QOL-weighted functional status scores will be most meaningful when presented alongside the patient’s objectively measured functional performances across the same set of activities. METHODS The FIM instrument3,4 was the objective measure used to show how to calculate QOL-weighted functional status. The methods illustrated are intended to be appropriate for use with any ordinal functional status measure that includes multiple activities. The FIM quantifies patients’ abilities to perform 6 ADLs (items A–F); 2 sphincter management functions (items G, H); 5 mobility activities (items I–M); and 5 social, cognitive, and communication functions (items N–R). Patients’ performance scores on each of the 18 items are combined in various ways, yielding total scores or profiles that objectively quantify the degree of assistance required by the person when performing activities. Total scores are formed by summing14 or otherwise combining15 the performances on some or on all of the 18 functional activities to produce single values. A profile, as distinct from a score, consists of the separately expressed performance levels on each of the 18 individual items. The Features-Resource Trade-Off Game The relative value of spending “resources” on alternative “features” is established through a trade-off process adopted from economic theories of scarce resources and marginal rates of substitution.16 Stineman et al10 previously showed the resulting preference stages formed by 4 groups of players based on the FIM. The game provides a means to weigh the value of various features relative to others by measuring where people would place set quantities of some type of resource. Here, each FIM item is a feature, and the resource is the number of independence levels available to be spent at any point in the Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
game process. When used to approximate QOL, the game documents a pattern of functional recovery for a hypothetical individual through an ordered number of preference stages. It is hypothesized that the QOL of the individual and of his/her family improves with each increase and that the life implication of that improvement will depend on the activities recovered. Game moves are based on the progress of a hypothetical individual living in an imaginary place in which all functional goals are equally accessible and attainable, whether or not effective therapy currently exists. Values, not physiologic feasibility of recovery, are being established. The following definitions are intended to clarify the process. Definitions The Features-Resource Trade-Off Game. The FeaturesResource Trade-Off Game is a process for identifying levels of functioning across a series of functional status activities intended to identify optimal patterns of recovery as perceived by an individual or by a group. The resulting profiles are referred to as “preference stages,” which yield utility weights for each activity. The game is played by 3, 5, or 7 people (optimally, an odd number) on a game board by moving “independence-level” pointers to show how the group believes it would want to recover function if patterns of recovery were under volitional control. Features. Features are the various activities in the functional status measure that are being ranked by value or recovery preference. Any multi-item functional status measure can be used to play the game. In the example being provided, each FIM item (eg, eating, grooming, bathing) represents a feature. Resources. Resources are the amount of independence that can be “spent” on alternative “features.” In the example provided, 1 independence level is 1 improvement point in 1 FIM activity. Preference stage. Preference stage is an optimum pattern of recovery as perceived by an individual or group assuming or imagining initial total dependence on others for the performance of each of a specified set of activities. It also assumes people are allowed to spend a limited number of independence levels. Utility weight. The utility weight is the relative value attached to one activity as opposed to all other activities in the set of features used to play the game as calculated from a preference stage. The guiding principle. The guiding principle is the vantage point, provided to the players, from which independence points are to be spent, which defines the overarching goals of recovery. Overarching goals might be “to return home” or “to return to work.” Vantage points can be from the person with disabilities, the person’s caregiver, or the payer of services. Any number of different principles could be formulated as a guide to building preference stages. Instructions for Playing the Game Players must be given verbal and written definitions of each of the functional status activities for which the game is being played. They were encouraged to seek clarifications of any item’s definition during the game. The definitions used here were those in the Uniform Data System for Medical Rehabilitation.4 Each of the 18 FIM items were also discussed. Players further received a written copy of the guiding principle for making moves. The principle used to obtain the data presented here, as adapted from the overarching goal of the independent living movement, was: “Make moves in a way that maximizes self-direction, minimizes the restrictiveness of any given envi-
MEASURING QUALITY OF LIFE BY SUBJECTIVE WEIGHTINGS, Stineman
ronment, and maximizes personal and economic freedom.”17 The vantage point was of the person with disabilities. All players were given a copy of a game board to follow the hypothetical individual’s progress. The board listed the 18 FIM activities along the left-hand side and the 7 performance levels across the top. At the beginning of the game, players were asked to imagine that they required total assistance in all activities. The board, at the start, had the column labeled “total assistance” filled with the independence-level pointers next to each activity signifying stage 1. These pointers were subsequently moved forward by the players to create the preference stages. To form higher stages, the independence levels of the FIM were spent by the players to advance from 1 (total dependence) to 7 (complete independence) in specific activities during the course of the game. To advance from one preference stage to the next, players were allowed to spend 18 independence levels in any way they saw fit, choosing to advance multiple levels for single activities or fewer levels for multiple activities. The average performance level of activities at any stage, by definition, corresponds to the stage number (ie, the performance levels across the 18 activities for stage 2 average 2, for stage 3 average 3, and so forth). The game consists of N⫺2 rounds, where N equals the number of performance levels defined for the activities of the assessment instrument being used. The number of activities defines the number of moves that make up a round. For the FIM example, there were 7⫺2⫽5 rounds with 18 moves for each round. Each round consists of 2 methods of advancing recovery: “free movement” and “zero-sum exchange” designated as step A and step B. Step A: free movement. The first player makes 1 move forward for the most valued activity. The players take turns until the number of moves equals the number of activities in the instrument. In this example, there were 18 free movements. No comments about the moves are allowed. This defines a preliminary preference stage. Step B: zero-sum exchange. Players are asked to reflect on the implications of the preliminary preference stage shown by the board configuration at the conclusion of the free-movement step. Each player is given the opportunity to change the board so that an activity he/she feels is more valuable is pushed forward at the expense of 1 retrograde move for another lessvalued activity. After the exchange, the player provides a rationale for it. The other players are offered an opportunity to present briefly the pros and cons of the exchange. The exchange is then put to a vote. If not agreed to by the majority, the board is returned to its earlier configuration. The configuration, after all players have offered 1 zero-sum exchange, defines the final preference stage. In this example, 5 players participated, so there were 5 zero-sum exchanges for each stage. Steps A and B are repeated to form the remaining stages. Before formulating a new stage, the scenario is reset by asking the players to imagine that they are at this new functional level. A simplified version of the game for an individual player, more appropriate to clinical practice, is described in the discussion. Use of Game Results Game results were obtained from two 5-person panels of rehabilitation clinicians and two 5-person panels of people with disabilities (consumers) living in the Philadelphia and Houston areas. Most consumers were dependent on wheelchairs as their primary means of mobility and several communicated through an assistant. All were extremely active, and several were employed. Consumers were selected to represent a wide variety of physically disabling conditions, including cerebral palsy, spinal
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muscular atrophy, tetraplegia, rheumatoid arthritis, and lowerlimb amputation. The clinician panels were formulated such that each panel included individuals with a wide range of clinical disciplines and experiences in diverse clinical settings. Disciplines were neuropsychology, occupational therapy, physiatry, physical therapy, psychology, rehabilitation nursing, speech pathology, and rehabilitation counseling. These panels were selected because we believed that their experiences placed them in a good position to understand the FIM activities most essential to independent living. The results were a set of 5 preference stages from each panel (published previously).10 These stages are used to show the following. 1. Calculation of utility weights for measuring the relative value of increasing independence in each functional activity compared with all other activities in a multiattribute instrument. 2. Use of utility weights to distinguish different goal preferences among groups of people with different life circumstances. 3. Development of value rulers from utility weights and their use in establishing the most meaningful patient goals. 4. Calculation of QOL-weighted functional status measures by combining utility weights with patients’ observed performances. 5. Interpretation of QOL-weighted scores. Three sets of FIM discharge scores from a program evaluation database that contained no personally identifying information were used to show the calculation and interpretation of QOLweighted functional status scores. Establishing item utility weights from preference stages. At the conclusion of the game, the utility weight for each activity is calculated by combining the cumulative FIM scores for stages 2 through 6. Stage 1 is total dependence in all 18 activities. Stage 7 is complete independence in all 18 activities. (Because there is no variability in level across the activities in these 2 latter stages, they are not included in the utility weight calculations.) This is shown later. Figure 1 shows preference stages established by the Philadelphia panel of consumers with physical disabilities. The 18 FIM activities are abbreviated around the periphery and concentric circles intersect the slices at points corresponding to the FIM performance levels. The innermost circle represents level 1 (total assistance), the intermediate circles represent levels 2 through 6, and the outer circle represents level 7 (complete independence). The shaded areas demarcate the FIM performance levels selected by the Philadelphia consumers10 for each activity at each of the 5 intermediate stages. A utility weight for a particular item, relative to the others, is determined by counting up all the shaded areas for a given activity at each stage and then adding the counts. For example, analyzing figure 1, the utility weight for eating as addressed by the Philadelphia consumers is 1⫹4⫹5⫹5⫹6⫽21. The utility weights for each activity and for each of the 4 panels were calculated from their preference stages in a similar fashion. Developing value rulers. Value rulers are graphic displays of utility weights ordered by magnitude that enable rapid comparisons of the preference similarities and differences between individuals or groups. Calculating QOL-weighted scores from item utility weights. QOL-weighted functional status scores are calculated by combining utility weights with patients’ objectively observed levels of performance in the same activities (unweighted scores). To calculate a QOL-weighted score for a patient, first multiply Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
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MEASURING QUALITY OF LIFE BY SUBJECTIVE WEIGHTINGS, Stineman
Fig 1. Philadelphia Consumer Panel. Shown is an example set of preference stages for Philadelphia consumers. Abbreviations: Ea, eating; Gr, grooming; Ba, bathing; DU, dressing upper body; DL, dressing lower body; To, toileting; Bl, bladder management; Bo, bowel management; ChT, chair transfer; Tot, toilet transfer; TuT, tub transfer; WC, walk wheelchair; St, stair climbing; Co, comprehension; Ex, expression; Si, social interaction; Ps, problem solving; Me, memory.
utility weights by his/her corresponding unweighted score for each activity. Sum the products. Divide by the sum of the value weights to obtain the average value weight. The sum of the weights for the FIM is 360. To rescale the QOL-weighted score so that it is comparable to the unweighted score, multiply the average value weight by the number of features in the scale (18 for the FIM). To estimate congruity of QOL-weighted and unweighted functional status scores, subtract the unweighted score from the QOL-weighted score. If the difference is positive, the patient is functioning at greater levels of independence Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
in more valued activities. If the difference is negative, the patient is functioning at greater independence in less valued activities. When interpreting the utility weight, or QOLweighted scores, and the value rulers derived from them, it is essential to recognize that as value-laden subjective metrics the numeric quantities are most relevant to the individuals who played the game. The particular game results presented here are provided as an illustration of techniques only and are not intended to be used in drawing conclusions about universal values.
MEASURING QUALITY OF LIFE BY SUBJECTIVE WEIGHTINGS, Stineman
Fig 2. Value rulers specific to each of the 4 groups. Abbreviations: PCO, Philadelphia consumers; PCL, Philadelphia clinicians; HCO, Houston consumers; HCL, Houston clinicians; a, eating; b, grooming; c, bathing; d, dressing upper; e, dressing lower; f, toileting; g, bladder; h, bowel; i, chair transfer; j, toilet transfer; k, tub transfer; l, walk/wheelchair; m, stairs; n, comprehension; o, expression; p, social interaction; q, problem solving; r, memory.
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Fig 3. A study of utility weight variability for the 18 FIM activities across the 4 groups. Abbreviations: see fig 2.
QOL-Weighted Functional Status Table 1 shows the actual FIM performance levels on each of the 18 FIM items for patients A, B, and C used to calculate QOL-weighted and unweighted FIM scores. The QOLweighted total FIM scores of patients A, B, and C are compared with their unweighted total FIM scores in table 2. That table shows the range in scores for each patient as determined from
Utility Weights and Value Rulers Item utility weights are ordered along value rulers specific to each panel (fig 2). Utility was consistently highest in cognitive and communication activities. Utility was consistently lowest for tub or shower transfer and stair climbing. Utility Weight Variability Across the Panels Variability in item utilities across all 4 panels is shown in figure 3. Distributions of utilities (y axis) are shown for each activity (x axis). When fewer than 4 utility values are displayed for an activity, it means that 2 or more of the panels have assigned that activity the same value. Utilities for eating, comprehension, and expression varied little, whereas utilities for bathing and grooming vary considerably. The achievement of independent communication and cognitive functioning was seen by all 4 panels as the most valuable outcome, assuming initial dependence in all activities. In figure 4, average item utilities from the 2 consumer panels are plotted on the x axis and average utilities from the 2 clinician panels on the y axis. The 45° line represents the position at which the clinician and consumer panel utilities are equal for an activity. Item m (stair climbing) was of an equally low utility for both types of panels. Although both the clinicians and consumers valued memory, problem solving, and social interaction highly, the utility of these items was even greater for the clinician than for the consumer panels. This type of graphic display can show how the functional goals set by 2 individuals (eg, a patient and family member) or by 2 groups of individuals (eg, patients and clinicians) would differ.
Fig 4. Comparison of utility weights comparing consumers and clinicians. See fig 2.
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MEASURING QUALITY OF LIFE BY SUBJECTIVE WEIGHTINGS, Stineman Table 1: Actual Performance Levels for 3 Patients Actual FIM Performance
Patient A
Patient B
Patient C
Eating Grooming Bathing Upper dressing Lower dressing Toileting Bladder Bowel Transfer bed Transfer toilet Transfer tub Locomotion Stairs Comprehension Expression Social interaction Memory Summed total
1 1 1 1 1 1 6 1 1 1 1 5 1 7 7 7 7 57
6 2 2 2 1 1 1 1 1 1 1 1 1 6 4 6 2 42
7 7 7 7 7 7 7 7 7 7 7 7 7 3 2 2 1 100
the utility weights of the different panels. These ranges are followed by the panel average QOL-weighted score for each patient and by the unweighted total FIM score. The last column of table 2 is the difference between the average QOL-weighted FIM scores and the unweighted FIM scores. Because patients A and B were functioning more independently in FIM activities that were perceived by the panels to be of relatively high value compared with the other activities, their QOL-weighted scores were higher than their unweighted FIM scores, producing positive differences. Conversely, because patient C was functioning more independently in activities with low value than in activities with high value, her QOL-weighted score was lower than her unweighted FIM score, producing a negative difference. This implies that the unweighted FIM score would tend to underestimate patient A and B’s function-related QOL, but overestimate patient C’s function-related QOL, at least from the vantage point of the panels of individuals who played the game in this example. DISCUSSION The game can be applied to elicit preferences for improvement in specific activities included in a functional status measure, thereby establishing the relative value or utility of being able to perform each component activity compared with the other activities. Utility weights are formed through the game process by measuring the degree to which groups of people would be willing to exchange the achievement of greater independence in 1 activity for lesser independence in a different activity. Those utility weights, in turn, can form value rulers for goal setting, or, when combined with patients’ objectively measured functional status, form QOL-weighted scores. We recognize that many aspects of life not considered as health or function, such as income, quality of environment, or freedom, can affect QOL.13 Consequently, we see QOL-weighted functional status scores as a metric for estimating only the subjective contribution of function to QOL. Function-related QOL is closely related to other aspects of life that affect well-being and, in fact, is likely influenced by those factors. For example, the value of being able to walk up stairs versus dress independently will depend on the architecture of one’s living space, who is available to provide help, and the personal implications Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
of being able to perform those activities. The methodology, as applied here to the FIM, produces QOL-weighted FIM scores. The QOL FIM is a single numeric index that translates patients’ objectively measured performance levels on each of the 18 component activities of the instrument into a single metric. That metric, along with value rulers, has many clinical, educational, research, and policy applications. The weights used in the QOL translation of the 3 sample patient FIM discharge scores were aggregated from the 4 consumer and clinician panel games. Thus, the resulting QOLweighted FIM scores represent the subjective points of view of the 20 panel members, rather than of the patients. Aggregated utility weights are appropriate to program evaluations or to continuous quality improvement. When estimating changes in QOL at the level of treatment populations, it is necessary to incorporate standard values as derived from the consensus of many people. In these applications, QOL-weighted scores established through utility weights from panel judgments are appropriate to differentiate between groups of people with better or worse function-related QOL. Subtracting rehabilitation admission QOL-weighted scores from discharge QOLweighted scores provides an estimate of the treatment population’s changes in function-related QOL, allowing that small increases in independence in the performance of a set of highly valued activities might represent a more desirable outcome than greater improvement in less valued activities. When interpreting QOL-weighted scores, it is essential to recognize that the implications depend on whose weightings were applied. We would discourage the reader from drawing any conclusions of generalizability regarding the particular utility weights used in this example. Had the 3 individuals whose FIM values were used to calculate the QOL-weighted scores provided their own game results, the resulting utility weights would have very different implications and, thus, applications. The resulting value rulers and person-specific QOL-weighted scores would reflect each persons’ subjective reaction to his/her function. Utility weights could now highlight the functional achievements the patient would most value. If a patient’s value ruler at admission to rehabilitation were to indicate that he/she most desires independence in bladder management, that would justify the spending of more resources toward meeting that goal. If the patient’s net change in QOL units is greater than his/her unweighted functional gain, then recovery occurred in areas that he/she most valued. Unweighted functional gain may over- or underestimate how individual patients value their rehabilitation outcomes. Therapists observing patients playing the game might gain a greater appreciation of their motivations and values. The game process could facilitate communication and education by forming an empathetic linkage with patients. People protect themselves from the negativity of others by erecting what Nathanson18 has called an empathic wall. Clinicians may tune out their patients’ reactions to disabilities, obscuring knowlTable 2: Comparing Objectively Measured FIM Performance to QOL Translations Range in QOL-Weighted QOL-Weighted QOL-Weighted FIM Across FIM Averaged Unweighted FIM⫺Unweighted Groups Across Groups FIM FIM (difference)
Patient A Patient B Patient C
69.7–77.0 48.6–53.0 83.6–88.8
73.3 50.6 86.2
57.0 42.0 100.0
⫹16.4 ⫹8.7 ⫺13.7
MEASURING QUALITY OF LIFE BY SUBJECTIVE WEIGHTINGS, Stineman
edge about the most troubling aspects of restrictions imposed by them. The process of playing the game cuts away the empathic wall, through guided communication and interaction about the therapeutic process and the patient’s current and desired states of functioning. This paves the way for communicating in difficult areas and for formulating the most relevant therapeutic approaches, through a participatory process that encourages the patient to contribute novel ideas to his/her own treatment planning.19 To be practical as a clinical tool, the group version of the game needs to be simplified and adopted to the individual. The Features-Research Trade-Off Game might be abbreviated for application to clinical practice in a number of ways. A simplified approach is illustrated—again, using the FIM. In this approach, the patient plays the game under clinician guidance. A guiding principle is provided, tailored to the process of goal setting and to the patients’ overarching life objectives. The therapist explains to the patient that the game process is a way to help set goals and explore approaches to therapy that will be most meaningful. The therapist invites the patient to imagine total dependence in all FIM activities. He/she is then encouraged to make 18 moves, as described in step A for the group version in the methods section. The 18 moves define preference stage 2. The clinician asks the patient to imagine that he/she is now functioning at that new level. He/she is encouraged to make another 18 moves, creating stage 3. This continues through formulation of the remaining preference stages, 4, 5, and 6. As the patient’s preference stages begin to meet and exceed his/her current status, the clinician encourages the patient to share the logic of his/her choices, focusing on contexts, such as anticipated family support, architectural qualities of the home, or goals such as returning home or to work. Individual value rulers and QOL-weighted scores can be created from the game results, as described for the group process. Step B is not performed in the individual version. Estimating population-level QOL is becoming increasingly important for setting health care policies in the United States and worldwide.20 Health policy decisions require choices about resource allocation across diseases and disability subgroups at considerable costs.21 These choices depend on measures that enable comparison of very different treatment approaches. Policy analysts might want to apply QOL-weighted functional status scores across large samples of patients. Such analyses applied to diverse groups of people require a common yardstick. It is conceivable that repeated application of the group version of the game could produce utility weights that are broadly applicable across many types and severities of impairment and sociodemographic subgroups. Yet, if different people have widely different preferences, the aggregation of utility weights will be inappropriate. With respect to variation, among the 4 panels studied, the utility of certain activities appeared stable, whereas others were more variable. This supports the feasibility of developing population utility weights for certain subsets of activities. Aggregation of utility weights for the purposes of public policy making would be open to serious objections if it resulted in penalizing certain individuals whose legitimate needs were not recognized.22 Additional research is needed to make conclusions about how different groups of people value achievements in various functional domains. Utility weights provide the means to explore differences in preferences between various rehabilitation stakeholders, for example, between patients and family members, men and women, paraplegics and tetraplegics, older people and younger people, those of different cultural heritages, or any other defined groups of individuals. The examples provided in this article compared utilities established by rehabilitation clini-
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cians with those established by consumers with disabilities (figs 3, 4), showing both similarities and differences in the values among the groups studied. Measures of QOL-weighted function might also be applied to clinical trials when there is a need to address how an intervention has changed functionrelated QOL. This would require the development of utility weights by groups drawn from the same population as that being enrolled in the trial. Life experience depends on a person’s potential to integrate self with surrounding physical and social environments.23,24 Because surrounding environments and life contexts differ among people, the value of being able to perform a specific activity may vary across different individuals and groups. An unweighted score defines a functional state objectively across all people. Once QOL-weighted, the score becomes qualitative in nature, and its numeric value will depend on whose utility weights were applied. Although our illustrations were for the FIM instrument, the development of utility weights might be explored by using any measure of health status, function, or participation, with multiple items and ordered categories. Each domain of health and disability has many components with potential bearing on QOL. To understand the implications of disability, each domain is optimally measured both objectively and subjectively.7 CONCLUSION QOL-weighted functional status scoring is in its infancy. Clinicians, educators, researchers, and policymakers can use utility weights, value rulers, and QOL-weighted functional status scores to measure what matters: what people value about their functional abilities and how those values affect QOL. Patients’ unweighted functional status performance scores provide objective information about activity limitations.24 The QOL translation of those scores expresses the perceived meaning of those limitations. Objective knowledge about a patient’s actual performance and the subjectively experienced meaning of that performance are equally important when establishing therapeutic goals and evaluating rehabilitation outcomes. Value weights obtained from individuals or groups can estimate the degree to which patients’ achievements are in accordance with their own, their families’, or their clinicians’ hopes for recovery. Finally, this technology enhances the potential to involve patients in helping to direct the objectives of their own rehabilitation programs. Through the experience of playing the game, policymakers, clinicians, researchers, and patients can better understand the therapeutic process and its relevance. References 1. Batavia AI. Assessing the function of functional assessment: a consumer perspective. Disabil Rehabil 1992;14:156-60. 2. Calman KC. Quality of life in cancer patients—an hypothesis. J Med Ethics 1984;10:124-7. 3. Hamilton BB, Granger CV, Sherwin FS, Zielezney M, Tashman JS. A uniform data system for medical rehabilitation. In: Fuhrer MJ, editor. Rehabilitation outcomes: analysis and measurement. Baltimore: PH Brookes; 1987. p 137-47. 4. Uniform Data System for Medical Rehabilitation. Guide for the Uniform Data Set for Medical Rehabilitation (Adult FIM), version 4.0. Buffalo (NY): Research Foundation, State Univ New York; 1994. 5. Bunch WH, Dvonch VM. The “value” of Functional Independence Measure scores. Am J Phys Med Rehabil 1994;73:40-3. 6. Kane RL, Rockwood T, Finch M, Philp I. Consumer and professional ratings of the importance of functional status components. Health Care Fin Rev 1977;19(2):11-22. 7. Testa MA, Simonson DC. Assessment of quality-of-life outcomes. N Engl J Med 1996;334:835-40. Arch Phys Med Rehabil Vol 84, Suppl 2, April 2003
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8. Dijkers M. Measuring quality of life: methodological issues. Am J Phys Med Rehabil 1999;78:286-300. 9. Torrance GW. Utility approach to measuring health-related quality of life. J Chronic Dis 1987;40:593-600. 10. Stineman MG, Maislin G, Nosek MA, Fiedler RC, Granger CV. Comparing consumer and clinician values for alternative functional states: application of a new feature-resource trade-off consensus building tool. Arch Phys Med Rehabil 1998;79:1522-9. 11. Lipscomb J. Value preferences for health: meaning, measurement, and use in program evaluation. In: Kane RL, Kane RA, editors. Values and long term care. Lexington (MA): DC Heath; 1982. p 27-67. 12. Sox HC, Blatt MA, Higgins MC, Marton KI. Medical decision making. Boston: Butterworth; 1988. 13. Guyatt GH, Feeny DH, Patrick DL. Measuring health-related quality of life. Ann Intern Med 1993;118:622-9. 14. Stineman MG, Shea JA, Jette A, et al. The Functional Independence Measure: tests of scaling assumptions, structure, and reliability across 20 diverse impairment categories. Arch Phys Med Rehabil 1996;77:1101-8. 15. Linacre JM, Heinemann AW, Wright BD, Granger CV, Hamilton BB. The structure and stability of the Functional Independence Measure. Arch Phys Med Rehabil 1994;75:127-32.
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16. Samuelson PA. Foundations of economic analysis. Cambridge: Harvard Univ Pr; 1947. ch V. 17. Frieden L, Richards L, Cole J, Bailey O. ILRU source book: a technical assistance manual on independent living. Houston: The Institute for Rehabilitation and Research; 1979. 18. Nathanson DL. Shame and pride: affect, sex, and the birth of the self. New York: Norton; 1992. 19. Ozer MN. Patient participation in the management of stroke rehabilitation. Top Stroke Rehabil 1999;6(1):43-59. 20. Burstrom K, Johannesson M, Diderichsen F. Health-related quality of life by disease and socio-economic group in the general population in Sweden. Health Policy 2001;55(1):51-69. 21. Guyatt GH, Naylor CD, Juniper E, Heyland DK, Jaeschke R, Cook DJ. Users’ guides to the medical literature. XII. How to use articles about health-related quality of life. Evidence-Based Medicine Working Group. JAMA 1997;277:1232-7. 22. Leplege A, Hunt S. The problem of quality of life in medicine. JAMA 1997;278:47-50. 23. Stineman MG. Defining the population, treatments, and outcomes of interest: reconciling the rules of biology with meaningfulness. Am J Phys Med Rehabil 2001;80:147-59. 24. World Health Organization. ICF: international classification of functioning, disability and health. Geneva: WHO; 2001.