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Reliability and validity of the Faces Pain Scale with older adults
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International Journal of Nursing Studies 43 (2006) 447–456 www.elsevier.com/locate/ijnurstu
Reliability and validity of the Faces Pain Scale with older adults Eun Joo Kima,, MaryBeth Tank Buschmannb a Department of Nursing, Daejeon University, 96-3, Yongun-dong, Dong-gu, Daejeon 300-716, Korea College of Nursing, University of Illinois at Chicago, 845 S. Damen Ave, Chicago, IL 60612-7350, USA
b
Received 21 July 2005; received in revised form 3 January 2006; accepted 4 January 2006
Abstract Background: The Faces Pain Scale (FPS) is effective with older adults in clinical assessment of pain intensity. The 0–10 numerical rating scale (NRS) has universally adapted for assessment of pain intensity. The commonly used versions of the FPS have six, seven or nine faces. Objectives: We proposed an 11 face modified version of the McGrath nine face FPS to compare with the 0–10 NRS without the mathematical translation. The psychometric properties of the proposed version were also investigated in a sample of Korean older adults. Design: This study employed methodological research design. Settings and participants: A sample of 31 older adults was recruited through local senior citizen centers to examine the construct validity and the test–retest reliability. For the concurrent validity testing, a sample of 85 older adults with chronic pain was recruited through a general hospital and an oriental medical hospital. Methods: The construct validity was examined by determining if the subjects perceive the FPS as representing pain and they agree on the rank of each face. The test–retest reliability was examined at a 2-week interval. The concurrent validity was examined by using the NRS and the Visual Analogue Scale (VAS). Results: Subjects perceived the 11 FPS as a pain measure, and the subjects’ agreements in the rank ordering of the faces were almost perfect (Kendall’s W ¼ :93, po:001). Cohen’s kappa of .61 (po:001) for test–retest reliability was acceptable in the cognitively intact subjects. Concurrent validity measured by the correlation between the FPS and the NRS (r ¼ :73, po:001) and the VAS (r ¼ :73, po:001) was supported. Conclusions: These results supported the appropriateness of the 11 FPS for use with the older adults in clinical practice to measure pain intensity. Additionally, this study provided cross-cultural evidence to evaluate usefulness of the FPS. r 2006 Elsevier Ltd. All rights reserved. Keywords: Aged; Pain measurement; Reliability and validity
What is already known about the topic? Corresponding author. Tel.: +82 42 280 2656;
fax: +82 42 274 2600. E-mail addresses: [email protected] (E.J. Kim), [email protected] (M.T. Buschmann).
Previous research indicated that the Faces Pain Scale (FPS) is effective with older adults FPS with the six, seven, or eleven faces was evaluated for use with older adults
The
0020-7489/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijnurstu.2006.01.001
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448
What this paper adds
We proposed an eleven face modified version of the
McGrath 9 face FPS to compare with the 0–10 NRS without the mathematical translation This study investigated the initial psychometric properties of the 11 face FPS using a Korean older adult sample This research results provided cross-cultural evidence to evaluate usefulness of the FPS
1. Introduction Many common physiological and chronic pathological changes that occur with aging put the older adult at risk for pain. In fact, pain is extremely common among older adults (Ferrell, 1991) and chronic pain is common due to the high prevalence of osteoarthritis, cancer and peripheral vascular disease (Egbert, 1991). Crook and colleagues (1984) reported that the incidence of pain was twice as great in people over 60 years of age than in those 60 and under. It is estimated that 25–70% of the adults over 60 years of age in the community (Ferrell and Ferrell, 1991; Roy and Thomas, 1987), and 45–80% of nursing home residents (Ferrell, 1995) in America suffer from significant pain. Prevalence of pain in Taiwanese nursing homes was reported as 65.3% (Tsai et al., 2004). Pain among the elderly is mostly constant and impacts on everyday lives. This pain interferes with the victim’s daily life and increases with age (Higgins et al., 2004; Thomas et al., 2004). All of which is probably an underestimate since accurate detection and assessment is a problem (Forrest, 1995). Although pain is common, as one grows older, it is not normal (Ferrell and Ferrell, 1990). Therefore, it is the responsibility of the health care provider to provide relief and comfort. In fact, the assessment of pain is now the 5th vital sign, along with temperature, pulse, respirations and blood pressure (Kirsch et al., 2000). The assessment of pain is difficult because it is multifaceted including affective, cognitive, physical, sensory, behavioral and sociocultural factors (McGuire, 1992), subjective (Ferrell, 1991) and done by self-report (Acute Pain Management Guideline Panel, 1992; Herr, 2002; McCaffery, 1968). Although pain is multifaceted in concept, subjective intensity is probably the aspect most often measured (Herr and Mobily, 1993). Forrest (1995) investigated four pain intensity assessment tools with older adults, the visual analogue scale (VAS), the verbal descriptor scale (VDS), the numerical rating scale (NRS) and the multidimensional McQuill Questionnaire. She found the VDS to be preferred in her study (Forrest, 1995). Herr and Mobily (1993) compared the VDS, NRS, pain thermometer, and Faces Pain Scale
(FPS) in older and young adults and found the VDS and the NRS to be preferred in the elderly. Several studies have investigated the psychometric properties of pain intensity scales for the older adults (Gagliese and Katz, 2003; Gagliese et al., 2005; Herr et al., 1998; Herr and Mobily, 1993; Scherder and Bouma, 2000; Taylor and Herr, 2002, 2003). The VDS and the NRS have adequate to good reliability and validity for measuring chronic pain intensity in the older adults (Gagliese and Melzack, 1997; Herr and Mobily, 1993). Taylor and Herr (2003) determined the reliability and validity of selected pain intensity scales such as the FPS, the VDS, the NRS, and the modified VDS. Concurrent validity of the FPS, the VDS, the NRS, and the modified VDS for use in the older adults was reported with Spearman rank correlation coefficients ranging from .74 to .96. Test–retest reliability at a 2week interval was acceptable with Spearman rank correlation coefficients ranging from .73 to .83 in cognitively intact older adults. While the FPS was originally developed for use in pediatrics (Bieri et al., 1990; Wong and Baker, 1988), it has been found to be valid and reliable in adults (Stuppy, 1998) and older adults (Herr et al., 1998; Taylor and Herr, 2002). Stuppy (1998) found that adults preferred the FPS or the NRS. The comprehension of the purpose of the FPS by the non-demented older adults was reported to be 100% (Scherder and Bouma, 2000). This is important because assessment is further complicated with cognitively impaired individuals due to their difficulty in self-report and communication in general (Ferrell et al., 1995). Anecdotal data appear to indicate that the FPS is effective with the cognitively impaired and end-of-life non-verbal individuals because it does not require reading, writing or energy for extensive expression (Fink and Gates, 2001; Herr, 2002). In fact, the FPS was preferred in both cognitively impaired and the cognitively intact older adults (Taylor and Herr, 2003) as well as by clinical staff for its ease of use. However, additional work is needed to establish its reliability and validity. There are several versions of the FPS, some with six (Wong and Baker, 1988), seven (Bieri et al., 1990) or nine faces (McGrath’s study as cited in Patt, 1993). None of the scales has 11 faces to compare with the 0–10 NRS without the mathematical translation. Since Dalton and McNaull (1998) recommend the universal adoption for the 0–10 NRS for clinical assessment of pain intensity and since its use is so common (American Pain Society (APS) Clinical Practice Guideline, 2002; McCaffery and Pasero, 1999), it has become the gold standard in clinical practice. Therefore, it would be useful to have a 0–10 FPS (11 faces in FPS as there are 11 numbers in NRS) that correlated with the 0–10 NRS. The present study investigated the validity and reliability of an 11 face (Fig. 1) modified version of the McGrath nine face FPS.
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Fig. 1. The 11 faces of the FPS.
One of the issues considered in this study is investigating the conceptual and psychometric characteristics of the 11 face FPS. Some researchers suggested that there are difficulties with the FPS distinguishing pain from other constructs, such as distress and anxiety (Hunter et al., 2000). Previous studies examined this issue of the FPS with children (Bieri et al., 1990) and with older adults (Taylor and Herr, 2002) and claimed appropriateness of the FPS for measuring pain intensity. Regarding this issue, the construct validity of the 11 face FPS was examined in the present study. For validity assessment of magnitude estimation scaling like the FPS, Waltz et al. (1991) suggested a method known as cross-modality matching. Crossmodality matching and related techniques may be the ideal methodology for psychometric evaluation of pain measures (Hicks et al., 2001; McGrath, 1987). The procedure includes the comparisons between the use of numerical estimates of magnitude and other response modalities (Waltz et al., 1991). In the present study, cross-modality matching was utilized to assess the construct validity of the FPS by having the subjects to match the pain intensity represented by a face in the FPS to a number. For testing the concurrent validity subjects also matched their ratings of pain using the FPS, the VAS, and the NRS, respectively. Testing reliability of the magnitude estimation scaling is generally accomplished using the test–retest procedure (Waltz et al., 1991). Possible problems with test–retest reliability were considered. First, unless the variable of the measure remains at the same level of intensity during the test and retest, the stability of the scale would not be assessed independently Waltz et al., 1991). Thus, in the
present study, the authors asked the subjects to recall and to rate the most severe pain ever felt in their lives, rather than asking them to rate the pain felt at the test period and retest period. Another problem is a memorybias effect because scoring may be based on memory of the face they responded to the prior FPS test. In this study, two weeks were chosen as the interval of test–retest to reduce the bias. The specific aims of this study were to examine: (a) the construct validity measured by determining if the subjects perceive FPS as representing pain more than other constructs; (b) the construct validity measured by determining the subject agreement on the rank of each face; (c) the test–retest reliability of responses on the FPS to rating a vividly remembered pain in their life; (d) the concurrent validity of the FPS with the older adults experiencing chronic pain.
2. Methodology 2.1. Construct validity and test–retest reliability testing in a community setting 2.1.1. Sample A total of 31 subjects were recruited through local senior citizen centers in Korea. The number of subjects was based on the sample size used in the previous research (Herr et al., 1998). Volunteers aged 65 years of age or older were initially screened by the research
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assistants using the Mini-Mental State Examination, Korean Version (K-MMSE) to determine the presence of cognitive impairment. Prior to screening the subjects, the researcher trained two research assistants who were registered nurses having experience in working with dementia patients. If the subjects were unable to follow simple directions, such as answering questions on the KMMSE, they were excluded. However, those with a score suggesting cognitive impairment were included as long as they were able to communicate. Other exclusion criteria included severe hearing or vision impairment. 2.1.2. Instrument The FPS used for this study is the McGrath nine face scale modified into an 11 face scale to compare to the numeric 0–10 rating scale. Based on a previous study (Herr et al., 1998), the tears on the faces of the original nine face scale were removed for preventing bias produced by personal beliefs related to pain expression. Scores from zero to 10 were assigned to the faces showing different amounts of pain, with zero implying ‘no pain’ and 10 implying ‘the worst pain possible’. Subjects pointed to the face indicating their current level of pain. The MMSE developed by Folstein et al. (1975) was used for the subject’s cognitive assessment in a community setting and a clinical setting. Reliability and validity have been reported (Folstein et al., 1975; Tombaugh and McIntyre, 1992). Kang et al. (1997) reported that sensitivities of the MMSE translated into the Korean language (K-MMSE) for dementia ranged from .70 to .93. Factor analysis on demented subjects revealed two factors for Alzheimer subjects and one factor for subjects with vascular dementia. At that time, concurrent validity was also established for the K-MMSE. The 11-item internal consistency reliability coefficient of the K-MMSE was Cronbach’s alpha of .71 (Kim and Buschmann, 1999). Agreement on items was ‘‘good to excellent’’ (kappas varying from .64 to 1.00) and overall inter-rater agreement was .86 (Lee, 1992). The internal consistency reliability coefficient of K-MMSE in this study was Cronbach’s alpha of .75 and .72 in the community setting and clinical setting, respectively. A score of less than 10 of K-MMSE corresponds to severe cognitive impairment (Kang et al., 1997). For the Korean elderly with poor education, three to four points were added to the obtained scores of K-MMSE as was highly recommended (Kwon and Park, 1989). The adjusted score of less than 19 of K-MMSE corresponds to moderate or definite cognitive impairment (Park and Kwon, 1989) and of X21 corresponds to no cognitive impairment (Kim et al., 2001). Therefore, in the present study, the adjusted score of p13 indicated severe cognitive impairment, of 14–20 indicated mild to moderate cognitive impairment, and of X21 indicated no cognitive impairment.
2.1.3. Procedures In order to determine construct validity of the FPS, the subjects were first asked to rate their degree of agreement between the faces and a given feeling/ emotion. The unlabeled set of 11 faces were presented to each subject six times (e.g., once for each feeling/ emotion). Each time the subject was asked, ‘‘Do these faces represent ____?’’ The question was completed each time using a different feeling/emotion in alphabetical order (i.e., anger, boredom, pain, sadness, sleepiness and sourness, respectively). This order of questioning prevented any bias of the data. The subject rated her/his degree of agreement with a number 1 (agree), a number 2 (do not know) or a number 3 (disagree). Based on the previous research (Herr et al., 1998; Taylor and Herr, 2002), theses constructs were selected in contrast with pain. Secondly, to determine the properties of the 11 faces of the scale, we asked the subject to arrange the 11 face cards in order. Each face of the FPS was placed on a 4 4 in card. In the rank-ordering task, we observed that the subjects had difficulty in arranging the 11 face cards in order in the pilot study. This difficulty in ordering 11 face cards without guidance may come from the subjects’ low educational level. Thus, research assistants placed three cards at the ends and the center, at the sacrifice of the accuracy in evaluating construct validity. We placed the first face (face number 0) at the beginning of the row and explained ‘‘This is a very happy face because there is no pain at all.’’, then we placed the last face (face number 10) at the end of the row and explained ‘‘This is a very sad face because it describes the worst pain possible.’’ Finally, we placed the neutral face (face number 5) in the middle of the row and explained, ‘‘This is a neutral face which occurs between ‘no pain’ and ‘the worst pain possible’.’’ Then, we laid all eight cards randomly on the desk and asked the subject to arrange faces numbers 1, 2, 3, and 4 in rank order of increasing pain between the first and the 6th faces (viz. face #0 and face #5), and to arrange faces numbers 6, 7, 8, and 9 in rank order of increasing pain between the 6th and 11th faces (viz. face #5 and face #10). Thirdly, using the pack of 11 face cards, we showed five possible random pairs of cards to each subject, one pair at a time, and asked them to indicate which card of each pair expressed more pain to test correct discrimination. Test–retest reliability of the FPS was examined at a 2week interval which is considered a memory-bias effect (Waltz et al., 1991). No matter what pain the subject was experiencing, the subject was asked to rate the most severe pain ever felt in his/her life. 2.2. Concurrent validity testing in a clinical setting 2.2.1. Sample A total of 85 older adults with chronic pain (i.e., a state of pain X6 months duration and for which the cause of the pain could not be removed) were recruited
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through a general hospital and an oriental medical hospital in Korea. The number of subjects was generated through Cohen’s (1988) power analysis for multiple correlations. A sample size of 85 would provide a power of .85 for three variables to be examined in their relationships at a ¼ :05 and a value of medium effect size (f ¼ :15) (Cohen, 1988; Volicer, 1984). Inclusion criteria were hospitalized clients or outpatient clinic clients aged 65 years of age or older and a signed consent form from the patient or family member. Exclusion criteria included severe hearing or vision impairment or inability to communicate or severe cognitive impairment based on a score of less than 14 on the K-MMSE. Since poor education was anticipated prior to collecting the data, exclusion criteria included a K-MMSE score of less than 14 points as a cut-off level (Kang et al., 1997; Kwon and Park, 1989). 2.2.2. Instruments The NRS consists of a vertical line calibrated with numbers from 0 as ‘no pain’ to 10 as ‘the worst pain possible’. Subjects pointed to the number that best reflected the level of pain, which was currently felt. The VAS consists of a 10 cm horizontal line anchored with ‘no pain’ on the left and ‘worst possible pain’ on the right. Subjects marked on the line indicating the intensity of pain they felt. A research assistant measured
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the length from the left anchor to the marked point with a 0–10 cm calibrator. 2.2.3. Procedures The subjects were asked to rate their current level of pain using the FPS, the NRS and the VAS.
3. Results 3.1. Construct validity and test–retest reliability in a community setting In the community setting, the mean age of the subjects was 77.32 years (SD ¼ 6.40). Sixteen subjects (51.6%) were female, and 15 subjects (48.4%) were male. Most subjects (26, 83.8%) had poor school education. Thirteen (41.9%) subjects attended grade school, and 13 (41.9%) had no school education. The mean score for the K-MMSE was 24.16 (SD ¼ 5.07) with a range from 11 to 30. Most subjects (24, 77.4%) scored 21 points or more for the K-MMSE, and six subjects (19.4%) scored 20 points or less (Table 1). Table 2 shows descriptive data on the degree of agreement for each construct, which is related to the subject’s perception of the FPS. Most subjects responded ‘agreed’ on the construct of pain (n ¼ 21,
Table 1 Demographic characteristics Variables
Community sample (n ¼ 31) N (%)
Age (years) 65–69 70–74 75–79 80–84 X85 Gender Female Male Educationb No school education Attend grade or 6th grade 9th grade High school Some college K-MMSE scoreb 0–20 21–30 a
4 (12.9) 6 (19.4) 8 (25.8) 11 (35.5) 2 (6.5)
Mean (SD) Range
77.32 (6.40) 65–88
N (%)
34(40.0) 26(30.6) 17(20.0) 7 (8.2) 1 (1.2)
16 (51.6) 15 (48.4)
44 (51.8) 41 (48.2)
13 (41.9) 13 (41.9) 3 (9.7) 1 (3.2) 1 (3.2)
25 (29.4) 41 (48.2) 6 (7.1) 7 (8.2) 5 (5.9)
6 (19.4) 24 (77.4)
24.16 (5.07) 11-30 24, 22-29c
Raw data were used for calculation of mean and standard deviation. Excluding missing data. c Median, interquartile range. b
Clinical sample (n ¼ 85) a
34 (40) 51 (60)
Mean (SD)a Range
72.85 (5.42) 65–86
22.00 (4.57) 14–30 22, 18–26c
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Table 2 Descriptive data for the subject’s perception of the FPS Agreed (1) N (%)
Neutral (2) N (%)
Disagreed (3) N (%)
Mean
SD
Pain Sourness Sleepiness Sadness Anger Boredom
21 7 6 13 17 8
9 8 8 8 8 14
1 16 17 10 6 9
1.35 2.29 2.35 1.90 1.64 2.03
.55 .83 .79 .87 .79 .75
Percent Accuracy
Construct
100 90 80 70 60 50 40 30 20 10 0
(67.7) (22.6) (19.4) (41.9) (54.8) (25.8)
93.5
90.3
83.9
77.4
(29.0) (25.8) (25.8) (25.8) (25.8) (45.2)
80.6
71 61.3 61.3
1
2
3
4
6 Faces
7
8
9
Fig. 2. The accuracy of ordering of faces.
67.7%). The mean rating was 1.35 (SD ¼ .55) of pain, followed by 1.64 (SD ¼ .79) of anger, and 1.90 (SD ¼ .87) of sadness. Repeated measures ANOVA showed that significant differences exist among the means of all constructs (F(5, 150) ¼ 8.62, po:001). Simple contrast test yielded that the mean rating of pain is significantly different from the mean of sourness (F(1, 30) ¼ 27.25, po:001), the mean of sleepiness (F(1, 30) ¼ 31, po:001), sadness (F(1, 30) ¼ 7.83, p ¼ :009), and boredom (F(1, 30) ¼ 13.87, p ¼ :001) and has marginally significant difference from anger (F(1, 30) ¼ 3.21, p ¼ :083). This means that the subjects perceived the FPS as representing pain rather than other constructs. Fig. 2 shows the accuracy of placing faces #1, 2, 3, 4 and 6, 7, 8, 9 in rank of increasing pain. Face #9 was placed with the highest accuracy of 93.5% and face #4 was placed with 90.3% accuracy. Faces #6 and #7 were placed with the lowest accuracy of 61.3%. Mean numbers of nominated rank positions of face were 1.35 of face #1, 2.03 of face #2, 2.77 of face #3, 3.84 of face #4, 5.45 of face #6, 5.90 of face #7, 6.74 of face #8, and 7.90 of face #9. Kendall’s coefficient of concordance (W) and its significant test were utilized to determine the degree of agreement on a rank order among the subjects and to determine whether the ordering the faces correctly was occurred by chance (Herr et al., 1998; Seigel and Castellan, 1988). Kendall’s W was .93 (po:001), indicating that agreement on a rank order among subjects is near perfect, and the rank order the
(3.2) (51.6) (54.8) (32.3) (19.4) (29.0)
subjects produced would not simply have occurred by chance. In order to test the subject’s discrimination in paired comparisons for all possible random pairs of face cards, a total of 155 trials were performed. Each combination had 3–4 trials. The pair of faces #4 and #5 and the pair of faces #6 and #7 resulted in the lowest correct rate of 71.4%. All pairs including face # 0, #1, and #2 were 100% correctly judged by subjects. The pair of face # 8 and #9 and the pair of face #9 and #10 resulted 87.5% and 75% of correct discrimination, respectively. In order to evaluate the test–retest reliability of the FPS, data collected at 2-week intervals were analyzed using Cohen’s kappa and the Spearman’s rank order correlation. The mean of subject’s pain score at the initial testing was 8.40 (SD ¼ 1.27), at the retesting was 8.47 (SD ¼ 1.50). Cohen’s kappa for the whole test–retest data could not be calculated due to lack of filling of the cells in the 2 2 matrix. Since subject’s cognitive impairment might impact his/her recalling the experienced pain, we analyzed test–retest data of subjects with K-MMSE score of 21 points or more, assuming their cognition intact. Cohen’s kappa in cognitively intact subjects was .61 (po:001), indicating that this proportion of subjects consistently rated the same face on both the initial and the second ratings of pain intensity. The Spearman’s rank order correlation coefficient for the test–retest was .60 (p ¼ :004) in all subjects and .74 (p ¼ :003) in the cognitively intact subjects, indicating acceptable test–retest reliability. 3.2. Concurrent validity of the FPS with the older adults with chronic pain in a clinical setting In the clinical setting, the mean age of the subjects was 72.85 years (SD ¼ 5.42). Forty-four subjects (51.8%) were female, and 41 subjects (48.2%) were male. Twenty-five (29.4%) subjects had no school education, and 41 (48.2%) attended grade school. The mean score on the K-MMSE for subjects was 22 (SD ¼ 4.57) (Table 1), with a range from 14 to 30. Fifty-one subjects (60.0%) scored 21 points or more for the K-MMSE, and 34 subjects (40.0%) scored 20 points or less (Table 1). The locations of pain complaints and the etiology of
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primary pain complaint were obtained from the medical records. Forty-five percent of the subjects reported more than one location for pain. The most common location of pain was back (30, 35.3%) followed by legs (24, 28.2%) and knee (14, 16.5%). Stroke was the most common etiology (24, 29.3%) of data obtained from 45 subjects from the oriental medical hospital. This reflects that Korean older adults with stroke are common, and these subjects prefer the oriental medical treatment. Cancer (12, 14.6%) is the second common etiology identified for the primary pain followed by arthritis (9, 11.2%), old fractures (6, 7.1%), spinal stenosis (5, 5.9%), muscle spasm (5, 5.9%), and osteoporosis (5, 5.9%). The mean of the subject’s pain intensity was 7.32 (SD ¼ 2.11) as measured by the FPS, 7.22 (SD ¼ 2.47) as measured by the NRS, and 6.96 (SD ¼ 2.72) as measured by the VAS. To determine if intensity estimates generated from three different tools were significantly different, we compared the means of pain intensity by using repeated measures ANOVA. Results indicate that pain intensities by the FPS, the NRS and the VAS were not significantly different (F(1.00, 68.00) ¼ 2.93, p ¼ .09); likewise the tools were not different in reporting the intensity of patient’s pain (Table 3). Table 4 shows the bivariate correlation Table 3 Pain intensity as measured by three pain scales Tool
Mean (SD)
FPS VAS NRS
7.32 (2.11) 6.96 (2.72) 7.22 (2.47)
dfa
MS
1.00, 68.00
8.40
P
2.93
.09
Table 4 Correlations between pain intensity rating scales VAS a
Total FPS VAS .73 NRS .73
b
c
Group1
Group2
Totala Group1b Group2c
— .76 .75
.68 .70
.91
— .88
coefficients between pain intensities measured by the FPS, the NRS and the VAS. The FPS had moderately strong correlation with the NRS (r ¼ :73, po:001) and the VAS (r ¼ :73, po:001). To evaluate the effects of the cognition impairment in using the FPS with the older adults, the subjects were assigned to one of two groups according to their K-MMSE score. For the Korean elderly with poor education, adjusted score of p20 was used as a criterion to split elderly into two groups (Kim et al., 2001; Kwon and Park, 1989). Therefore, scores of p20 comprised a cognitively impaired group and scores of X21 comprised a cognitively intact group. We assigned 34 subjects with K-MMSE score of 20 points or less to Group 1, assuming their cognition was mildly impaired. Fifty-one subjects with K-MMSE score of 21 points or more were assigned to Group 2, assuming their cognition intact. While correlation between the VAS and the NRS of the cognitively impaired group (r ¼ .88, Po:001) was weaker than the correlation of the cognitively intact group (r ¼ .92, Po:001), correlation between the FPS and the NRS of the cognitively impaired group (r ¼ .75, Po:001) was slightly stronger than correlation of the cognitively intact group (r ¼ .70, Po:001). These results suggest that the FPS is valid, and the validity in measuring pain intensity is maintained even in older adults with cognitive impairment.
4. Discussion F
An adjusted degree of freedom based on lower-bound epsilon was used. a The sphericity test was rejected (Mauchly’s W ¼ :28, po:001).
FPS
453
.92
Note: Numbers represent Spearman rho correlation coefficients. Po:001 for all values. a n ¼ 85. b Group 1 was composed of 34 subjects with MMSE-K score of 14–20. c Group 2 was composed of 51 subjects with MMSE-K score of 21–30.
In this study, we attempted to determine the psychometric properties of an 11 face FPS and additionally to evaluate the scale’s usefulness with the older adults experiencing chronic pain. The FPS has been interchangeably used with various pain intensity scales in the clinical field. The 0–10 NRS or the VAS are commonly used, but researchers suggested that the FPS is appropriate for use with older adult patients. Recent research gave support for reliability and validity of the FPS with six or seven faces for measuring pain intensity in African-American or Caucasian older adult cohorts (Herr et al., 1998; Taylor and Herr, 2002; Stuppy, 1998; Wynne et al., 2000). However, some researchers raised questions about the appropriateness of the interchanging of the six or seven face with the 0–10 NRS or the VAS without the mathematical transformation (Freeman et al., 2001). Using the 0–10 FPS with psychometric properties that are correlated with the NRS would provide better understanding and communication for older adult’s pain interventions. The subjects participating in this study provided additional cross-cultural evidence to evaluate usefulness of the FPS because Korean older adults dwelling in the community and experiencing chronic pain were included in this study. Although this study was conducted in a
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different culture than that in which the original tool was developed, the findings of the present study are similar to (not much different from) the results of testing the various FPSs with the American elderly population (Stuppy, 1998). Previous research evaluated the construct validity of Bieri et al’s (1990) seven face FPS with older adults and reported that many subjects agreed that the faces represented pain, as well as representing other constructs, depending on how the subjects were cued (Herr et al., 1998; Taylor and Herr, 2002). Similar responses appeared in this study, since subjects responded with some agreements that the FPS could also represent other constructs according to the cue they received. This indicated that our FPS could also serve as a pain measure including affective components. However, we found a significant difference between the construct of pain and all other constructs (i.e., sourness, sleepiness, sadness, and boredom) with the exception of anger. Theses findings are in contrast to Herr et al.’ s (1998) who used the seven face FPS with Caucasian older adults and found that only the construct of anger was significantly different from all other constructs (e.g., pain, sourness, sleepiness, sadness, and boredom). On the other hand, Taylor and Herr (2002) applied the same seven face FPS to African-American older adults and reported that the construct of pain was significantly different from the constructs of sour, sleep and boredom, but not different from sadness and anger. Since we applied the 11 face FPS to Korean older adults, this particular finding may result from cultural differences, as well as instrumental differences. The subjects’ agreements in the rank ordering of the faces were near perfect. Faces #6 and #7 were the faces that caused most confusion in the ordering test and the paired comparison test. Some amendments of face #6 and face #7 through further study would improve its psychometric property. Cohen’s kappa for test–retest reliability at a 2-week interval was .61 (po:001) in the cognitively intact subjects. As a general guide, Cohen’s kappa ranging from .40 to .80 is acceptable, interpreting mild to moderate consistency (Lewis, 1999). These results provide support that the 11 face FPS is stable and reproducible for using over time. The Spearman’s rank order correlation coefficients for the test–retest ranged from .60 to .74. The higher value of the correlation coefficient resulted only when analyzing cognitively intact subjects. This is to be expected, considering the impact of memory deficits with cognitively impairment subjects. These findings are similar to the previous study with the seven face FPS (Taylor and Herr, 2003), in which the Spearman’s rank order correlation coefficients at a 2-week interval were .79 and .81 in the cognitively impaired and the cognitively intact African-American older adults, respectively. The sample size used in the present study is small but justified by a power analysis
(see 2.2.1 Sample). Replication studies with larger samples would confirm its test–retest reliability of the 11 face FPS for cognitively impaired population. The concurrent validity of the FPS with the older adults experiencing current pain was strongly supported. This result also provided the appropriateness of the FPS in use with the older adult in clinical practice to measure his/her pain intensity. Using only the data composed of cognitively impaired subjects, we found the relationship of the VAS and the NRS was weaker, whereas the relationship of the FPS and the NRS became stronger. These results support the potential use of the facial scale with the cognitively impaired older adults postulated by some researchers (Herr et al., 1998; Taylor and Herr, 2002; Wynne et al., 2000). It is the first study that has been done in justifying the FPS in older adults with respect to reliability and validity against a gold standard of the NRS. Perhaps future work could add to this knowledge.
5. Conclusion This study reveals the initial psychometric properties of the 11 face FPS using a Korean older adult sample. The FPS is appropriate for use to assess the pain intensity of older adults, even when their cognition is mildly or moderately impaired. The concurrent validity, especially, the correlation between the FPS and the NRS was strongly supported. In clinical practice, the 11 face FPS may be interchangeably used with the universally adopted NRS without the mathematical translation. The FPS is ordinal in nature, indicating that the interval of the 0–10 scale is not artificially implying equal increments. Further study evaluating linear increment and the intervals among the faces will provide further psychometric soundness of the 11 face FPS.
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International Journal of Nursing Studies 43 (2006) 447–456 www.elsevier.com/locate/ijnurstu
Reliability and validity of the Faces Pain Scale with older adults Eun Joo Kima,, MaryBeth Tank Buschmannb a Department of Nursing, Daejeon University, 96-3, Yongun-dong, Dong-gu, Daejeon 300-716, Korea College of Nursing, University of Illinois at Chicago, 845 S. Damen Ave, Chicago, IL 60612-7350, USA
b
Received 21 July 2005; received in revised form 3 January 2006; accepted 4 January 2006
Abstract Background: The Faces Pain Scale (FPS) is effective with older adults in clinical assessment of pain intensity. The 0–10 numerical rating scale (NRS) has universally adapted for assessment of pain intensity. The commonly used versions of the FPS have six, seven or nine faces. Objectives: We proposed an 11 face modified version of the McGrath nine face FPS to compare with the 0–10 NRS without the mathematical translation. The psychometric properties of the proposed version were also investigated in a sample of Korean older adults. Design: This study employed methodological research design. Settings and participants: A sample of 31 older adults was recruited through local senior citizen centers to examine the construct validity and the test–retest reliability. For the concurrent validity testing, a sample of 85 older adults with chronic pain was recruited through a general hospital and an oriental medical hospital. Methods: The construct validity was examined by determining if the subjects perceive the FPS as representing pain and they agree on the rank of each face. The test–retest reliability was examined at a 2-week interval. The concurrent validity was examined by using the NRS and the Visual Analogue Scale (VAS). Results: Subjects perceived the 11 FPS as a pain measure, and the subjects’ agreements in the rank ordering of the faces were almost perfect (Kendall’s W ¼ :93, po:001). Cohen’s kappa of .61 (po:001) for test–retest reliability was acceptable in the cognitively intact subjects. Concurrent validity measured by the correlation between the FPS and the NRS (r ¼ :73, po:001) and the VAS (r ¼ :73, po:001) was supported. Conclusions: These results supported the appropriateness of the 11 FPS for use with the older adults in clinical practice to measure pain intensity. Additionally, this study provided cross-cultural evidence to evaluate usefulness of the FPS. r 2006 Elsevier Ltd. All rights reserved. Keywords: Aged; Pain measurement; Reliability and validity
What is already known about the topic? Corresponding author. Tel.: +82 42 280 2656;
fax: +82 42 274 2600. E-mail addresses: [email protected] (E.J. Kim), [email protected] (M.T. Buschmann).
Previous research indicated that the Faces Pain Scale (FPS) is effective with older adults FPS with the six, seven, or eleven faces was evaluated for use with older adults
The
0020-7489/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijnurstu.2006.01.001
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448
What this paper adds
We proposed an eleven face modified version of the
McGrath 9 face FPS to compare with the 0–10 NRS without the mathematical translation This study investigated the initial psychometric properties of the 11 face FPS using a Korean older adult sample This research results provided cross-cultural evidence to evaluate usefulness of the FPS
1. Introduction Many common physiological and chronic pathological changes that occur with aging put the older adult at risk for pain. In fact, pain is extremely common among older adults (Ferrell, 1991) and chronic pain is common due to the high prevalence of osteoarthritis, cancer and peripheral vascular disease (Egbert, 1991). Crook and colleagues (1984) reported that the incidence of pain was twice as great in people over 60 years of age than in those 60 and under. It is estimated that 25–70% of the adults over 60 years of age in the community (Ferrell and Ferrell, 1991; Roy and Thomas, 1987), and 45–80% of nursing home residents (Ferrell, 1995) in America suffer from significant pain. Prevalence of pain in Taiwanese nursing homes was reported as 65.3% (Tsai et al., 2004). Pain among the elderly is mostly constant and impacts on everyday lives. This pain interferes with the victim’s daily life and increases with age (Higgins et al., 2004; Thomas et al., 2004). All of which is probably an underestimate since accurate detection and assessment is a problem (Forrest, 1995). Although pain is common, as one grows older, it is not normal (Ferrell and Ferrell, 1990). Therefore, it is the responsibility of the health care provider to provide relief and comfort. In fact, the assessment of pain is now the 5th vital sign, along with temperature, pulse, respirations and blood pressure (Kirsch et al., 2000). The assessment of pain is difficult because it is multifaceted including affective, cognitive, physical, sensory, behavioral and sociocultural factors (McGuire, 1992), subjective (Ferrell, 1991) and done by self-report (Acute Pain Management Guideline Panel, 1992; Herr, 2002; McCaffery, 1968). Although pain is multifaceted in concept, subjective intensity is probably the aspect most often measured (Herr and Mobily, 1993). Forrest (1995) investigated four pain intensity assessment tools with older adults, the visual analogue scale (VAS), the verbal descriptor scale (VDS), the numerical rating scale (NRS) and the multidimensional McQuill Questionnaire. She found the VDS to be preferred in her study (Forrest, 1995). Herr and Mobily (1993) compared the VDS, NRS, pain thermometer, and Faces Pain Scale
(FPS) in older and young adults and found the VDS and the NRS to be preferred in the elderly. Several studies have investigated the psychometric properties of pain intensity scales for the older adults (Gagliese and Katz, 2003; Gagliese et al., 2005; Herr et al., 1998; Herr and Mobily, 1993; Scherder and Bouma, 2000; Taylor and Herr, 2002, 2003). The VDS and the NRS have adequate to good reliability and validity for measuring chronic pain intensity in the older adults (Gagliese and Melzack, 1997; Herr and Mobily, 1993). Taylor and Herr (2003) determined the reliability and validity of selected pain intensity scales such as the FPS, the VDS, the NRS, and the modified VDS. Concurrent validity of the FPS, the VDS, the NRS, and the modified VDS for use in the older adults was reported with Spearman rank correlation coefficients ranging from .74 to .96. Test–retest reliability at a 2week interval was acceptable with Spearman rank correlation coefficients ranging from .73 to .83 in cognitively intact older adults. While the FPS was originally developed for use in pediatrics (Bieri et al., 1990; Wong and Baker, 1988), it has been found to be valid and reliable in adults (Stuppy, 1998) and older adults (Herr et al., 1998; Taylor and Herr, 2002). Stuppy (1998) found that adults preferred the FPS or the NRS. The comprehension of the purpose of the FPS by the non-demented older adults was reported to be 100% (Scherder and Bouma, 2000). This is important because assessment is further complicated with cognitively impaired individuals due to their difficulty in self-report and communication in general (Ferrell et al., 1995). Anecdotal data appear to indicate that the FPS is effective with the cognitively impaired and end-of-life non-verbal individuals because it does not require reading, writing or energy for extensive expression (Fink and Gates, 2001; Herr, 2002). In fact, the FPS was preferred in both cognitively impaired and the cognitively intact older adults (Taylor and Herr, 2003) as well as by clinical staff for its ease of use. However, additional work is needed to establish its reliability and validity. There are several versions of the FPS, some with six (Wong and Baker, 1988), seven (Bieri et al., 1990) or nine faces (McGrath’s study as cited in Patt, 1993). None of the scales has 11 faces to compare with the 0–10 NRS without the mathematical translation. Since Dalton and McNaull (1998) recommend the universal adoption for the 0–10 NRS for clinical assessment of pain intensity and since its use is so common (American Pain Society (APS) Clinical Practice Guideline, 2002; McCaffery and Pasero, 1999), it has become the gold standard in clinical practice. Therefore, it would be useful to have a 0–10 FPS (11 faces in FPS as there are 11 numbers in NRS) that correlated with the 0–10 NRS. The present study investigated the validity and reliability of an 11 face (Fig. 1) modified version of the McGrath nine face FPS.
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Fig. 1. The 11 faces of the FPS.
One of the issues considered in this study is investigating the conceptual and psychometric characteristics of the 11 face FPS. Some researchers suggested that there are difficulties with the FPS distinguishing pain from other constructs, such as distress and anxiety (Hunter et al., 2000). Previous studies examined this issue of the FPS with children (Bieri et al., 1990) and with older adults (Taylor and Herr, 2002) and claimed appropriateness of the FPS for measuring pain intensity. Regarding this issue, the construct validity of the 11 face FPS was examined in the present study. For validity assessment of magnitude estimation scaling like the FPS, Waltz et al. (1991) suggested a method known as cross-modality matching. Crossmodality matching and related techniques may be the ideal methodology for psychometric evaluation of pain measures (Hicks et al., 2001; McGrath, 1987). The procedure includes the comparisons between the use of numerical estimates of magnitude and other response modalities (Waltz et al., 1991). In the present study, cross-modality matching was utilized to assess the construct validity of the FPS by having the subjects to match the pain intensity represented by a face in the FPS to a number. For testing the concurrent validity subjects also matched their ratings of pain using the FPS, the VAS, and the NRS, respectively. Testing reliability of the magnitude estimation scaling is generally accomplished using the test–retest procedure (Waltz et al., 1991). Possible problems with test–retest reliability were considered. First, unless the variable of the measure remains at the same level of intensity during the test and retest, the stability of the scale would not be assessed independently Waltz et al., 1991). Thus, in the
present study, the authors asked the subjects to recall and to rate the most severe pain ever felt in their lives, rather than asking them to rate the pain felt at the test period and retest period. Another problem is a memorybias effect because scoring may be based on memory of the face they responded to the prior FPS test. In this study, two weeks were chosen as the interval of test–retest to reduce the bias. The specific aims of this study were to examine: (a) the construct validity measured by determining if the subjects perceive FPS as representing pain more than other constructs; (b) the construct validity measured by determining the subject agreement on the rank of each face; (c) the test–retest reliability of responses on the FPS to rating a vividly remembered pain in their life; (d) the concurrent validity of the FPS with the older adults experiencing chronic pain.
2. Methodology 2.1. Construct validity and test–retest reliability testing in a community setting 2.1.1. Sample A total of 31 subjects were recruited through local senior citizen centers in Korea. The number of subjects was based on the sample size used in the previous research (Herr et al., 1998). Volunteers aged 65 years of age or older were initially screened by the research
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assistants using the Mini-Mental State Examination, Korean Version (K-MMSE) to determine the presence of cognitive impairment. Prior to screening the subjects, the researcher trained two research assistants who were registered nurses having experience in working with dementia patients. If the subjects were unable to follow simple directions, such as answering questions on the KMMSE, they were excluded. However, those with a score suggesting cognitive impairment were included as long as they were able to communicate. Other exclusion criteria included severe hearing or vision impairment. 2.1.2. Instrument The FPS used for this study is the McGrath nine face scale modified into an 11 face scale to compare to the numeric 0–10 rating scale. Based on a previous study (Herr et al., 1998), the tears on the faces of the original nine face scale were removed for preventing bias produced by personal beliefs related to pain expression. Scores from zero to 10 were assigned to the faces showing different amounts of pain, with zero implying ‘no pain’ and 10 implying ‘the worst pain possible’. Subjects pointed to the face indicating their current level of pain. The MMSE developed by Folstein et al. (1975) was used for the subject’s cognitive assessment in a community setting and a clinical setting. Reliability and validity have been reported (Folstein et al., 1975; Tombaugh and McIntyre, 1992). Kang et al. (1997) reported that sensitivities of the MMSE translated into the Korean language (K-MMSE) for dementia ranged from .70 to .93. Factor analysis on demented subjects revealed two factors for Alzheimer subjects and one factor for subjects with vascular dementia. At that time, concurrent validity was also established for the K-MMSE. The 11-item internal consistency reliability coefficient of the K-MMSE was Cronbach’s alpha of .71 (Kim and Buschmann, 1999). Agreement on items was ‘‘good to excellent’’ (kappas varying from .64 to 1.00) and overall inter-rater agreement was .86 (Lee, 1992). The internal consistency reliability coefficient of K-MMSE in this study was Cronbach’s alpha of .75 and .72 in the community setting and clinical setting, respectively. A score of less than 10 of K-MMSE corresponds to severe cognitive impairment (Kang et al., 1997). For the Korean elderly with poor education, three to four points were added to the obtained scores of K-MMSE as was highly recommended (Kwon and Park, 1989). The adjusted score of less than 19 of K-MMSE corresponds to moderate or definite cognitive impairment (Park and Kwon, 1989) and of X21 corresponds to no cognitive impairment (Kim et al., 2001). Therefore, in the present study, the adjusted score of p13 indicated severe cognitive impairment, of 14–20 indicated mild to moderate cognitive impairment, and of X21 indicated no cognitive impairment.
2.1.3. Procedures In order to determine construct validity of the FPS, the subjects were first asked to rate their degree of agreement between the faces and a given feeling/ emotion. The unlabeled set of 11 faces were presented to each subject six times (e.g., once for each feeling/ emotion). Each time the subject was asked, ‘‘Do these faces represent ____?’’ The question was completed each time using a different feeling/emotion in alphabetical order (i.e., anger, boredom, pain, sadness, sleepiness and sourness, respectively). This order of questioning prevented any bias of the data. The subject rated her/his degree of agreement with a number 1 (agree), a number 2 (do not know) or a number 3 (disagree). Based on the previous research (Herr et al., 1998; Taylor and Herr, 2002), theses constructs were selected in contrast with pain. Secondly, to determine the properties of the 11 faces of the scale, we asked the subject to arrange the 11 face cards in order. Each face of the FPS was placed on a 4 4 in card. In the rank-ordering task, we observed that the subjects had difficulty in arranging the 11 face cards in order in the pilot study. This difficulty in ordering 11 face cards without guidance may come from the subjects’ low educational level. Thus, research assistants placed three cards at the ends and the center, at the sacrifice of the accuracy in evaluating construct validity. We placed the first face (face number 0) at the beginning of the row and explained ‘‘This is a very happy face because there is no pain at all.’’, then we placed the last face (face number 10) at the end of the row and explained ‘‘This is a very sad face because it describes the worst pain possible.’’ Finally, we placed the neutral face (face number 5) in the middle of the row and explained, ‘‘This is a neutral face which occurs between ‘no pain’ and ‘the worst pain possible’.’’ Then, we laid all eight cards randomly on the desk and asked the subject to arrange faces numbers 1, 2, 3, and 4 in rank order of increasing pain between the first and the 6th faces (viz. face #0 and face #5), and to arrange faces numbers 6, 7, 8, and 9 in rank order of increasing pain between the 6th and 11th faces (viz. face #5 and face #10). Thirdly, using the pack of 11 face cards, we showed five possible random pairs of cards to each subject, one pair at a time, and asked them to indicate which card of each pair expressed more pain to test correct discrimination. Test–retest reliability of the FPS was examined at a 2week interval which is considered a memory-bias effect (Waltz et al., 1991). No matter what pain the subject was experiencing, the subject was asked to rate the most severe pain ever felt in his/her life. 2.2. Concurrent validity testing in a clinical setting 2.2.1. Sample A total of 85 older adults with chronic pain (i.e., a state of pain X6 months duration and for which the cause of the pain could not be removed) were recruited
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through a general hospital and an oriental medical hospital in Korea. The number of subjects was generated through Cohen’s (1988) power analysis for multiple correlations. A sample size of 85 would provide a power of .85 for three variables to be examined in their relationships at a ¼ :05 and a value of medium effect size (f ¼ :15) (Cohen, 1988; Volicer, 1984). Inclusion criteria were hospitalized clients or outpatient clinic clients aged 65 years of age or older and a signed consent form from the patient or family member. Exclusion criteria included severe hearing or vision impairment or inability to communicate or severe cognitive impairment based on a score of less than 14 on the K-MMSE. Since poor education was anticipated prior to collecting the data, exclusion criteria included a K-MMSE score of less than 14 points as a cut-off level (Kang et al., 1997; Kwon and Park, 1989). 2.2.2. Instruments The NRS consists of a vertical line calibrated with numbers from 0 as ‘no pain’ to 10 as ‘the worst pain possible’. Subjects pointed to the number that best reflected the level of pain, which was currently felt. The VAS consists of a 10 cm horizontal line anchored with ‘no pain’ on the left and ‘worst possible pain’ on the right. Subjects marked on the line indicating the intensity of pain they felt. A research assistant measured
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the length from the left anchor to the marked point with a 0–10 cm calibrator. 2.2.3. Procedures The subjects were asked to rate their current level of pain using the FPS, the NRS and the VAS.
3. Results 3.1. Construct validity and test–retest reliability in a community setting In the community setting, the mean age of the subjects was 77.32 years (SD ¼ 6.40). Sixteen subjects (51.6%) were female, and 15 subjects (48.4%) were male. Most subjects (26, 83.8%) had poor school education. Thirteen (41.9%) subjects attended grade school, and 13 (41.9%) had no school education. The mean score for the K-MMSE was 24.16 (SD ¼ 5.07) with a range from 11 to 30. Most subjects (24, 77.4%) scored 21 points or more for the K-MMSE, and six subjects (19.4%) scored 20 points or less (Table 1). Table 2 shows descriptive data on the degree of agreement for each construct, which is related to the subject’s perception of the FPS. Most subjects responded ‘agreed’ on the construct of pain (n ¼ 21,
Table 1 Demographic characteristics Variables
Community sample (n ¼ 31) N (%)
Age (years) 65–69 70–74 75–79 80–84 X85 Gender Female Male Educationb No school education Attend grade or 6th grade 9th grade High school Some college K-MMSE scoreb 0–20 21–30 a
4 (12.9) 6 (19.4) 8 (25.8) 11 (35.5) 2 (6.5)
Mean (SD) Range
77.32 (6.40) 65–88
N (%)
34(40.0) 26(30.6) 17(20.0) 7 (8.2) 1 (1.2)
16 (51.6) 15 (48.4)
44 (51.8) 41 (48.2)
13 (41.9) 13 (41.9) 3 (9.7) 1 (3.2) 1 (3.2)
25 (29.4) 41 (48.2) 6 (7.1) 7 (8.2) 5 (5.9)
6 (19.4) 24 (77.4)
24.16 (5.07) 11-30 24, 22-29c
Raw data were used for calculation of mean and standard deviation. Excluding missing data. c Median, interquartile range. b
Clinical sample (n ¼ 85) a
34 (40) 51 (60)
Mean (SD)a Range
72.85 (5.42) 65–86
22.00 (4.57) 14–30 22, 18–26c
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452
Table 2 Descriptive data for the subject’s perception of the FPS Agreed (1) N (%)
Neutral (2) N (%)
Disagreed (3) N (%)
Mean
SD
Pain Sourness Sleepiness Sadness Anger Boredom
21 7 6 13 17 8
9 8 8 8 8 14
1 16 17 10 6 9
1.35 2.29 2.35 1.90 1.64 2.03
.55 .83 .79 .87 .79 .75
Percent Accuracy
Construct
100 90 80 70 60 50 40 30 20 10 0
(67.7) (22.6) (19.4) (41.9) (54.8) (25.8)
93.5
90.3
83.9
77.4
(29.0) (25.8) (25.8) (25.8) (25.8) (45.2)
80.6
71 61.3 61.3
1
2
3
4
6 Faces
7
8
9
Fig. 2. The accuracy of ordering of faces.
67.7%). The mean rating was 1.35 (SD ¼ .55) of pain, followed by 1.64 (SD ¼ .79) of anger, and 1.90 (SD ¼ .87) of sadness. Repeated measures ANOVA showed that significant differences exist among the means of all constructs (F(5, 150) ¼ 8.62, po:001). Simple contrast test yielded that the mean rating of pain is significantly different from the mean of sourness (F(1, 30) ¼ 27.25, po:001), the mean of sleepiness (F(1, 30) ¼ 31, po:001), sadness (F(1, 30) ¼ 7.83, p ¼ :009), and boredom (F(1, 30) ¼ 13.87, p ¼ :001) and has marginally significant difference from anger (F(1, 30) ¼ 3.21, p ¼ :083). This means that the subjects perceived the FPS as representing pain rather than other constructs. Fig. 2 shows the accuracy of placing faces #1, 2, 3, 4 and 6, 7, 8, 9 in rank of increasing pain. Face #9 was placed with the highest accuracy of 93.5% and face #4 was placed with 90.3% accuracy. Faces #6 and #7 were placed with the lowest accuracy of 61.3%. Mean numbers of nominated rank positions of face were 1.35 of face #1, 2.03 of face #2, 2.77 of face #3, 3.84 of face #4, 5.45 of face #6, 5.90 of face #7, 6.74 of face #8, and 7.90 of face #9. Kendall’s coefficient of concordance (W) and its significant test were utilized to determine the degree of agreement on a rank order among the subjects and to determine whether the ordering the faces correctly was occurred by chance (Herr et al., 1998; Seigel and Castellan, 1988). Kendall’s W was .93 (po:001), indicating that agreement on a rank order among subjects is near perfect, and the rank order the
(3.2) (51.6) (54.8) (32.3) (19.4) (29.0)
subjects produced would not simply have occurred by chance. In order to test the subject’s discrimination in paired comparisons for all possible random pairs of face cards, a total of 155 trials were performed. Each combination had 3–4 trials. The pair of faces #4 and #5 and the pair of faces #6 and #7 resulted in the lowest correct rate of 71.4%. All pairs including face # 0, #1, and #2 were 100% correctly judged by subjects. The pair of face # 8 and #9 and the pair of face #9 and #10 resulted 87.5% and 75% of correct discrimination, respectively. In order to evaluate the test–retest reliability of the FPS, data collected at 2-week intervals were analyzed using Cohen’s kappa and the Spearman’s rank order correlation. The mean of subject’s pain score at the initial testing was 8.40 (SD ¼ 1.27), at the retesting was 8.47 (SD ¼ 1.50). Cohen’s kappa for the whole test–retest data could not be calculated due to lack of filling of the cells in the 2 2 matrix. Since subject’s cognitive impairment might impact his/her recalling the experienced pain, we analyzed test–retest data of subjects with K-MMSE score of 21 points or more, assuming their cognition intact. Cohen’s kappa in cognitively intact subjects was .61 (po:001), indicating that this proportion of subjects consistently rated the same face on both the initial and the second ratings of pain intensity. The Spearman’s rank order correlation coefficient for the test–retest was .60 (p ¼ :004) in all subjects and .74 (p ¼ :003) in the cognitively intact subjects, indicating acceptable test–retest reliability. 3.2. Concurrent validity of the FPS with the older adults with chronic pain in a clinical setting In the clinical setting, the mean age of the subjects was 72.85 years (SD ¼ 5.42). Forty-four subjects (51.8%) were female, and 41 subjects (48.2%) were male. Twenty-five (29.4%) subjects had no school education, and 41 (48.2%) attended grade school. The mean score on the K-MMSE for subjects was 22 (SD ¼ 4.57) (Table 1), with a range from 14 to 30. Fifty-one subjects (60.0%) scored 21 points or more for the K-MMSE, and 34 subjects (40.0%) scored 20 points or less (Table 1). The locations of pain complaints and the etiology of
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primary pain complaint were obtained from the medical records. Forty-five percent of the subjects reported more than one location for pain. The most common location of pain was back (30, 35.3%) followed by legs (24, 28.2%) and knee (14, 16.5%). Stroke was the most common etiology (24, 29.3%) of data obtained from 45 subjects from the oriental medical hospital. This reflects that Korean older adults with stroke are common, and these subjects prefer the oriental medical treatment. Cancer (12, 14.6%) is the second common etiology identified for the primary pain followed by arthritis (9, 11.2%), old fractures (6, 7.1%), spinal stenosis (5, 5.9%), muscle spasm (5, 5.9%), and osteoporosis (5, 5.9%). The mean of the subject’s pain intensity was 7.32 (SD ¼ 2.11) as measured by the FPS, 7.22 (SD ¼ 2.47) as measured by the NRS, and 6.96 (SD ¼ 2.72) as measured by the VAS. To determine if intensity estimates generated from three different tools were significantly different, we compared the means of pain intensity by using repeated measures ANOVA. Results indicate that pain intensities by the FPS, the NRS and the VAS were not significantly different (F(1.00, 68.00) ¼ 2.93, p ¼ .09); likewise the tools were not different in reporting the intensity of patient’s pain (Table 3). Table 4 shows the bivariate correlation Table 3 Pain intensity as measured by three pain scales Tool
Mean (SD)
FPS VAS NRS
7.32 (2.11) 6.96 (2.72) 7.22 (2.47)
dfa
MS
1.00, 68.00
8.40
P
2.93
.09
Table 4 Correlations between pain intensity rating scales VAS a
Total FPS VAS .73 NRS .73
b
c
Group1
Group2
Totala Group1b Group2c
— .76 .75
.68 .70
.91
— .88
coefficients between pain intensities measured by the FPS, the NRS and the VAS. The FPS had moderately strong correlation with the NRS (r ¼ :73, po:001) and the VAS (r ¼ :73, po:001). To evaluate the effects of the cognition impairment in using the FPS with the older adults, the subjects were assigned to one of two groups according to their K-MMSE score. For the Korean elderly with poor education, adjusted score of p20 was used as a criterion to split elderly into two groups (Kim et al., 2001; Kwon and Park, 1989). Therefore, scores of p20 comprised a cognitively impaired group and scores of X21 comprised a cognitively intact group. We assigned 34 subjects with K-MMSE score of 20 points or less to Group 1, assuming their cognition was mildly impaired. Fifty-one subjects with K-MMSE score of 21 points or more were assigned to Group 2, assuming their cognition intact. While correlation between the VAS and the NRS of the cognitively impaired group (r ¼ .88, Po:001) was weaker than the correlation of the cognitively intact group (r ¼ .92, Po:001), correlation between the FPS and the NRS of the cognitively impaired group (r ¼ .75, Po:001) was slightly stronger than correlation of the cognitively intact group (r ¼ .70, Po:001). These results suggest that the FPS is valid, and the validity in measuring pain intensity is maintained even in older adults with cognitive impairment.
4. Discussion F
An adjusted degree of freedom based on lower-bound epsilon was used. a The sphericity test was rejected (Mauchly’s W ¼ :28, po:001).
FPS
453
.92
Note: Numbers represent Spearman rho correlation coefficients. Po:001 for all values. a n ¼ 85. b Group 1 was composed of 34 subjects with MMSE-K score of 14–20. c Group 2 was composed of 51 subjects with MMSE-K score of 21–30.
In this study, we attempted to determine the psychometric properties of an 11 face FPS and additionally to evaluate the scale’s usefulness with the older adults experiencing chronic pain. The FPS has been interchangeably used with various pain intensity scales in the clinical field. The 0–10 NRS or the VAS are commonly used, but researchers suggested that the FPS is appropriate for use with older adult patients. Recent research gave support for reliability and validity of the FPS with six or seven faces for measuring pain intensity in African-American or Caucasian older adult cohorts (Herr et al., 1998; Taylor and Herr, 2002; Stuppy, 1998; Wynne et al., 2000). However, some researchers raised questions about the appropriateness of the interchanging of the six or seven face with the 0–10 NRS or the VAS without the mathematical transformation (Freeman et al., 2001). Using the 0–10 FPS with psychometric properties that are correlated with the NRS would provide better understanding and communication for older adult’s pain interventions. The subjects participating in this study provided additional cross-cultural evidence to evaluate usefulness of the FPS because Korean older adults dwelling in the community and experiencing chronic pain were included in this study. Although this study was conducted in a
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different culture than that in which the original tool was developed, the findings of the present study are similar to (not much different from) the results of testing the various FPSs with the American elderly population (Stuppy, 1998). Previous research evaluated the construct validity of Bieri et al’s (1990) seven face FPS with older adults and reported that many subjects agreed that the faces represented pain, as well as representing other constructs, depending on how the subjects were cued (Herr et al., 1998; Taylor and Herr, 2002). Similar responses appeared in this study, since subjects responded with some agreements that the FPS could also represent other constructs according to the cue they received. This indicated that our FPS could also serve as a pain measure including affective components. However, we found a significant difference between the construct of pain and all other constructs (i.e., sourness, sleepiness, sadness, and boredom) with the exception of anger. Theses findings are in contrast to Herr et al.’ s (1998) who used the seven face FPS with Caucasian older adults and found that only the construct of anger was significantly different from all other constructs (e.g., pain, sourness, sleepiness, sadness, and boredom). On the other hand, Taylor and Herr (2002) applied the same seven face FPS to African-American older adults and reported that the construct of pain was significantly different from the constructs of sour, sleep and boredom, but not different from sadness and anger. Since we applied the 11 face FPS to Korean older adults, this particular finding may result from cultural differences, as well as instrumental differences. The subjects’ agreements in the rank ordering of the faces were near perfect. Faces #6 and #7 were the faces that caused most confusion in the ordering test and the paired comparison test. Some amendments of face #6 and face #7 through further study would improve its psychometric property. Cohen’s kappa for test–retest reliability at a 2-week interval was .61 (po:001) in the cognitively intact subjects. As a general guide, Cohen’s kappa ranging from .40 to .80 is acceptable, interpreting mild to moderate consistency (Lewis, 1999). These results provide support that the 11 face FPS is stable and reproducible for using over time. The Spearman’s rank order correlation coefficients for the test–retest ranged from .60 to .74. The higher value of the correlation coefficient resulted only when analyzing cognitively intact subjects. This is to be expected, considering the impact of memory deficits with cognitively impairment subjects. These findings are similar to the previous study with the seven face FPS (Taylor and Herr, 2003), in which the Spearman’s rank order correlation coefficients at a 2-week interval were .79 and .81 in the cognitively impaired and the cognitively intact African-American older adults, respectively. The sample size used in the present study is small but justified by a power analysis
(see 2.2.1 Sample). Replication studies with larger samples would confirm its test–retest reliability of the 11 face FPS for cognitively impaired population. The concurrent validity of the FPS with the older adults experiencing current pain was strongly supported. This result also provided the appropriateness of the FPS in use with the older adult in clinical practice to measure his/her pain intensity. Using only the data composed of cognitively impaired subjects, we found the relationship of the VAS and the NRS was weaker, whereas the relationship of the FPS and the NRS became stronger. These results support the potential use of the facial scale with the cognitively impaired older adults postulated by some researchers (Herr et al., 1998; Taylor and Herr, 2002; Wynne et al., 2000). It is the first study that has been done in justifying the FPS in older adults with respect to reliability and validity against a gold standard of the NRS. Perhaps future work could add to this knowledge.
5. Conclusion This study reveals the initial psychometric properties of the 11 face FPS using a Korean older adult sample. The FPS is appropriate for use to assess the pain intensity of older adults, even when their cognition is mildly or moderately impaired. The concurrent validity, especially, the correlation between the FPS and the NRS was strongly supported. In clinical practice, the 11 face FPS may be interchangeably used with the universally adopted NRS without the mathematical translation. The FPS is ordinal in nature, indicating that the interval of the 0–10 scale is not artificially implying equal increments. Further study evaluating linear increment and the intervals among the faces will provide further psychometric soundness of the 11 face FPS.
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