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The test–retest reliability and concurrent validity of the Subjective Complaints Questionnaire for low back pain
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Manual Therapy 14 (2009) 283e291 www.elsevier.com/math
Original Article
The testeretest reliability and concurrent validity of the Subjective Complaints Questionnaire for low back pain Jon Joseph Ford a,*, Ian Story b, Joan McMeeken a a
School of Physiotherapy, The University of Melbourne, Parkville, Victoria 3010, Australia b Faculty of Health and Behavioural Science, Deakin University, Australia
Received 25 August 2005; received in revised form 6 February 2008; accepted 27 February 2008
Abstract Physiotherapists commonly record detailed patient information regarding subjective complaints for low back pain (LBP), particularly to assist in the process of classifying patients into specific subgroups. A self-administered Subjective Complaints Questionnaire for LBP (SCQ-LBP) measuring such information was developed for the purposes of future clinical research, particularly in the area of LBP classification. The development comprised literature review, feedback from experienced physiotherapists and pilot questionnaire testing in a patient population. Testeretest reliability of the questionnaire in a self administered format as well as concurrent validity against a suitable reference standard was evaluated. The agreement between the self administered questionnaire compared to when administered by a physiotherapist was also tested as the latter method is the most common form of retrieving subjective complaints in clinical practice. Thirty participants with LBP were recruited and at least moderate testeretest reliability was demonstrated in 56 of the 57 self administered questionnaire items. Preliminary evidence was found supporting the concurrent validity of selected items. At least moderate agreement was demonstrated in 51 of the 57 items when comparing between the self administered and physiotherapist administered conditions. The questionnaire is a useful tool for collecting subjective complaints information, particularly for clinical research on the classification of LBP, however, further research regarding validity is required. Ó 2008 Elsevier Ltd. All rights reserved. Keywords: Back pain; Classification; Questionnaire; Validity
1. Introduction Subjective complaints, reported by the sufferer in spoken or written form, are commonly documented as part of the standard assessment of low back pain (LBP). In clinical practice physiotherapists use a detailed subjective complaints interview to retrieve large amounts of * Corresponding author. Tel.: þ61 03 9607 3051; fax: þ61 03 9670 3080. E-mail address: [email protected] (J.J. Ford). 1356-689X/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.math.2008.02.010
information regarding the nature of symptoms, aggravating/easing factors, 24 h symptom behaviour, history and special questions (McKenzie et al., 2003; Maitland, 2005). This subjective complaints information can then be used to classify patients into subgroups that receive specific treatment (Delitto et al., 1995; McKenzie et al., 2003; Maitland, 2005). A common clinical example of using subjective complaints in the classification of LBP is the identification of an inflammatory cause of symptoms using criteria such as constancy of pain and a perception of stiffness in the injured area lasting at least 1 h after
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waking. Such patients may respond more effectively to anti-inflammatory modalities rather than treatment directed at a mechanical cause of symptoms (McKenzie et al., 2003; Maitland, 2005). Improved classification of LBP has been described as a high research priority by an esteemed international working group (Borkan and Cherkin, 1996). However, a number of review papers show that published classification systems have yet to demonstrate adequate reliability or validity and that methodological problems are common (Riddle, 1998; Petersen, 1999; Ford et al., 2007). One of the issues in the literature evaluating classification systems for LBP is the use of unreliable or poorly validated measurement tools for collecting data relevant to the classification process (Riddle, 1998; Petersen, 1999; Ford et al., 2007). There is relatively little research into reliable and valid methods of measuring subjective complaints. Only one study has reported on a comprehensive tool for measuring subjective complaints in individuals with LBP. The questionnaire developed included items such as the nature of symptoms, aggravating factors and history and variable testeretest reliability was found for the different questionnaire components (Walsh and Coggon, 1991). A 1-year retest period was used to minimise memory effects, however, a potential adverse consequence of this approach on the results may have been a spontaneous change in the nature and/or severity of the LBP. In addition the details of questionnaire wording and scoring were not described. The Multi-perspective Multi-dimensional Pain Assessment Protocol has been developed as a self administered questionnaire for chronic pain. It contains items on patient details, nature of symptoms, aggravating and easing factors, 24 h behaviour and history (Rucker et al., 1996). The questionnaire was developed with a view to maximising content validity and on evaluation, acceptable reliability and validity were demonstrated. However, the items in the questionnaire were not sufficiently comprehensive or specific to be used for the assessment of LBP patients when compared to accepted methods currently in widespread clinical use by physiotherapists (McKenzie et al., 2003; Maitland, 2005). A number of recent papers have evaluated the reliability of a variety of classification systems, however, typically subjective complaints are either poorly defined or insufficiently comprehensive to reflect the clinical practice of physiotherapists (Heiss et al., 2004; Petersen et al., 2004; Bertilson et al., 2006; Dankaerts et al., 2006; Fritz et al., 2006). One paper has been published investigating the reliability of the McKenzie classification system using a specific assessment form that included subjective complaints information (Clare et al., 2005). However, the ability of the form itself to reliably retrieve information from patients on retesting was not evaluated.
On the basis of this insufficient literature, there are limited options for clinical researchers wishing to use a reliable and valid questionnaire that comprehensively assesses subjective complaints for LBP. The aims of this study were therefore to develop a questionnaire for the self administered measurement of subjective complaints in LBP, and to evaluate its testeretest reliability and concurrent validity. Self administered questionnaires are an efficient method of data collection in clinical research. The purpose of this study was not to investigate the value of a particular classification system for LBP, but rather to establish a reliable and valid tool for the measurement of subjective complaints for use in future clinical research, particularly in the area of classification.
2. Method 2.1. Questionnaire development The critical components of our Subjective Complaints Questionnaire for low back pain (SCQ-LBP) comprised nature of symptoms, aggravating and easing factors, 24 h behaviour, and history. These components were predetermined based on clinical approaches commonly used by physiotherapists (McKenzie et al., 2003; Maitland, 2005). The specific questionnaire items were developed in four stages: literature review, operational definition of questionnaire items, peer review of the questionnaire, and pilot testing on individuals with LBP. A literature review was performed using the Current Contents database from years 1970 to 2003 inclusive. This database is a multidisciplinary current awareness web resource providing access to complete bibliographic information from over 8000 of the world’s leading scholarly journals. It includes databases with extensive coverage in the social and behavioural sciences as well as clinical medicine. Key words for the search were ‘‘back pain and validity’’ combined in separate searches with ‘‘subjective’’, ‘‘history’’ and ‘‘questionnaire’’. Full text copies of all identified papers were then retrieved. Further papers were unearthed by cross-referencing from the retrieved papers. On review of this literature, pain drawings as a measure of the nature of symptoms were found to be reliable (Margolis et al., 1986; Uden et al., 1988; Weiner et al., 1998) and some evidence of validity as a tool for classification was demonstrated (Uden and Landin, 1987; Mann et al., 1993; Ohnmeiss et al., 1995) although this latter conclusion has been disputed (Rankine et al., 1998). Preliminary evidence was found for the reliability and validity of a self administered questionnaire measuring aggravating factors in LBP (Roach et al., 1994, 1995, 1997). Studies evaluating the reliability or validity of
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24 h symptom behaviour had not been published for LBP. The two studies evaluating the reliability and validity of questionnaires measuring the history of LBP showed poor results (Biering-Sorensen and Hilden, 1984; Burdorf and Laan, 1991) potentially due to the influence of recall issues. Given the limited validation of many of the predefined critical subjective complaints components, items for our SCQ-LBP were chosen from the above literature if reliability and/or preliminary validity had been demonstrated (Margolis et al., 1986; Uden et al., 1988; Roach et al., 1994, 1995, 1997; Weiner et al., 1998). Where no such evidence existed, questionnaire items were selected from publications where subjective complaints were well described, either from the above literature or the descriptive literature on LBP (Boissonnault and Di Fabio, 1996; McKenzie et al., 2003; Maitland, 2005) and chronic injury (Rucker, 1996). Following the literature review an initial draft version of the SCQ-LBP was developed and distributed to two senior coordinators of the musculoskeletal physiotherapy postgraduate program from Universities in Victoria, Australia, and three physiotherapists with at least 5 years clinical experience working predominantly with chronic LBP. The feedback received was primarily in relation to scoring issues and consistency of wording between items. The second draft of the SCQ-LBP was self administered to 13 individuals with chronic LBP. Further modification to the SCQ-LBP was made to items where consistent feedback was given resulting in the final version of the SCQ-LBP (see Manual Therapy website).
2.2. Reliability and concurrent validity of the SCQ-LBP Participants were recruited from patients referred to physiotherapy private practices in Melbourne, Australia. Inclusion criteria were a primary problem of LBP, aged over 18 years, no signs or symptoms of serious nonmusculoskeletal pathology, and literacy in spoken and written English. In order to evaluate testeretest reliability in a self administered condition (SA), the SCQ-LBP was completed by participants twice within a period of 24e48 h. Under this condition, participants were given the questionnaire to complete without assistance. Reliability was tested only for the SA as our aim was to develop a reliable and valid measure that for pragmatic reasons in relation to clinical research was self administered. In order to evaluate concurrent and face validity participants performed specific items from the SCQ-LBP whilst being observed by physiotherapists (PO) and in
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also completed the full questionnaire in a physiotherapist administered condition (PA). Concurrent validity is a research design used to evaluate the ability of a newly developed measure to predict the results of an existing measure that represents an irrefutable truth or criterion standard (Portney and Watkins, 1993; Anastasi and Urbina, 1997). Often the newer measure is more convenient, less invasive or less costly than the criterion standard. However, in practice such absolute measures are rarely available and a more appropriate comparison is often with a reference standard that is the best available measure of truth (Portney and Watkins, 1993). In the current study the concurrent validity of the self administered SCQ-LBP (as a more convenient and cost effective measure for clinical research) was evaluated for its ability to predict the results of the physiotherapist observed condition (PO) (the reference standard). In the PO, the participant was asked to perform specific aggravating factors from the SCQ-LBP that could be replicated in a clinical environment such as sitting tolerance. The physiotherapist observed and questioned the participant regarding pain response according to a predetermined protocol in order to standardise measurement procedures. Time related variables were measured using a stopwatch. For example, time to onset of lumbar symptoms when in erect sitting, and time to the point where erect sitting could no longer be tolerated were measured. These time values were then compared to the response for the same items in the SA. In the PA a physiotherapist read each questionnaire item to the participant and filled in the participant responses. Clarification regarding questionnaire items was provided by the physiotherapist to the participant as required, and in accordance with a standardised protocol. The PA was intended to replicate the current clinical method of retrieving subjective complaints by physiotherapists (Maitland, 2005). Rather than representing an adequate reference standard, the SA was compared to the PA to evaluate whether the role of practitioner clarification was necessary in a clinical research setting. This comparison could therefore be considered an investigation of the face validity of the self administered SCQ-LBP (Portney and Watkins, 1993; Anastasi and Urbina, 1997). Each participant completed four administrations of the SCQ-LBP (initial SA, retest SA, PO and PA) according to one of six predetermined combinations of possible order, sequentially applied to each participant, to eliminate any effect of the order of administration on the results. To minimise any 24 h variation in the participants’ LBP, all data collection occurred at the same time of day. In addition, to evaluate spontaneous change between data collection sessions the Quebec Back Pain Disability Scale (Kopec et al., 1995) was completed at each questionnaire administration including the PO.
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2.3. Analysis Calculation of agreement was made on comparisons between the following SCQ-LBP conditions: initial SAeretest SA, initial SAePA and initial SAePO. Kappa statistics were used for all data with four or less response categories. For response categories of five or more weighted Kappa was calculated. Moderate agreement was defined as being greater than or equal to 0.4, and substantial agreement greater than or equal to 0.6 (Landis and Koch, 1977). For interval data mean differences and standard deviations (SDs) were calculated for each condition comparison (Bland and Altman, 1986).
3. Results Thirty participants provided informed consent and completed the data collection. There were no withdrawals from the study. The demographic and clinical characteristics of the sample are presented in Table 1. A one-way repeated measures analysis of variance found no significant within participant difference in the Quebec Back Pain Disability Scale scores across the measurement sessions (df ¼ 3.26, F ¼ 0.42, p ¼ 0.66). This indicates that spontaneous change over Table 1 Demographic and clinical characteristics for each group given as the mean (SD) or the number (%). Characteristic
Mean/SD (N ¼ 30)
Age (years)
42 (9.3)
Gender Male Female
Number/ percentage (N ¼ 30)
11 (37%) 19 (63%)
Weight (kg)
79 (15)
Height (cm)
175 (11)
Education Complete primary Complete secondary Complete tertiary
11 (37%) 10 (33%) 9 (30%)
Compensable Yes No
30 (100%) 0 (0%)
Duration of LBP 2e3 months 4e6 months 7e12 months More than 12 months
1 1 5 23
Past history of lumbar surgery Yes No
6 (20%) 24 (80%)
(3%) (3%) (17%) (77%)
time had no significant effect on disability and is therefore unlikely to have influenced the level of agreement observed. Mean differences and SDs were calculated for the pain drawing data and the level of agreement determined by judgement (Bland and Altman, 1986). The area score method (Parker et al., 1995) was used to count the number of grids where symptoms were marked. The maximum number of grids possible to mark was 264. The mean difference between the area scores in the initial SAeretest SA comparison was 0.60 (SD 6.56) and only five of the 30 participants had a difference of over five points. Higher levels of agreement were demonstrated on the initial SAePA comparison. The maximum number of symptoms descriptors was six on the pain drawing and the initial SAeretest SA comparison difference was 0.07 (SD 1.04). Only four of the 30 participants had a difference of over one point. Similar figures on the initial SAe PA comparison was observed. It was judged that sufficient agreement was observed on the initial SAe retest SA and initial SAePA comparisons for both the pain drawing area score and number of symptom descriptors. Substantial agreement was therefore found in 44 out of 57 items on the initial SAeretest SA comparisons. Moderate agreement was found in a further 12 items, with one item having less than moderate agreement. The results of the testeretest reliability of the SCQ-LBP in the SA are summarised in Table 2. Substantial agreement was found in one out of seven items on the initial SAePO comparisons with moderate agreement in a further four items. Two items had less than moderate agreement. The results of this comparison are presented in Table 3. Substantial agreement was found in 37 out of 57 items on comparison between the initial SAePA with moderate agreement in a further 14 items. However, six items had less than moderate agreement. These results are presented in Table 4.
4. Discussion The SCQ-LBP was developed using the methodology of literature review, review from a panel of experienced physiotherapists, and pilot testing on a sample of individuals with LBP. The testeretest reliability of the developed questionnaire was acceptable. Specifically, at least moderate agreement was found on 56 of the total 57 items on testeretest of the SCQ-LBP in the SA. The concurrent validity of the SCQ-LBP was examined by a comparison of the SA to the PO. In the PO each participant was tested in real time for tolerances to performing specific aggravating factors
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J.J. Ford et al. / Manual Therapy 14 (2009) 283e291 Table 2 Testeretest reliability of the SCQ-LBP (initial SAeretest SA). SCQ-LBP item (number of participants)
Kappa (95% CI)
Pain drawing item Area of symptoms (30) Number of symptom descriptors (30) Presence of leg pain (30) Presence of dermatomal symptoms (30) Presence of distal paraesthesia (30)
0.55 (0.20e0.90) 0.66 (0.31e1.00) 0.57 (0.22e0.92)
Symptom details Presence of pins and needles (29) Area of most severe pain (23) Presence of foot drop (29) Lumbar symptoms deep or superficial (29) Leg symptoms deep or superficial (29) Symptom relationship (29)
0.73 0.78 1.00 0.72 0.73 0.63
Aggravating factors Onset of symptoms while walking (28) Duration of walking limited by symptoms (27) Onset of symptoms while standing (27) Duration of standing limited by symptoms (29) Onset of symptoms while erect sitting (28) Duration of erect sitting limited by symptoms (29) Onset of symptoms while slumped sitting (29) Duration of slumped sitting limited by symptoms (29) Onset of symptoms while lying supine (29) Duration of lying supine limited by symptoms (28) Onset of symptoms while lying prone (29) Duration of lying prone limited by symptoms (27) Symptoms aggravated by getting into car (28) Components of getting into car that aggravate (24) Symptoms aggravated by sitting to standing (30) Components of sit to stand that aggravate symptoms (29) Symptoms aggravated by cough/sneeze (30) Presence of symptoms worse on one side (30) Most comfortable side to lie on (29) Easing factors Whether standing eases symptoms (29) Whether sitting eases symptoms (29) Whether sitting in a couch eases symptoms (29) Whether walking eases symptoms (29) Whether lying supine eases symptoms (29) Whether crook lying eases symptoms (29) Whether lying on the sore side eases symptoms (29) Whether lying on the good side eases symptoms (27) Whether lying prone eases symptoms (29) History of symptoms Whether current symptoms are the first episode (30) Duration of current symptoms (29) Number of episodes of symptoms (28) Time from first episode of symptoms (28) Whether symptoms chronic or recurrent (28) Mechanism of injury for current symptoms (28) Time of onset of current symptoms (29) Behaviour of current symptoms after onset (28) History of manual handling at work (28) History of over the past three days Time of day when symptoms worst (29) Presence of trouble getting to sleep (29) Presence of waking at night (29) Reason for waking at night (28)
Weighted Kappa (95% CI)
Mean difference (SD) 0.60 (5.54) 0.07 (1.05)
(0.38e1.00) (0.47e1.00) (0.63e1.00) (0.43e1.00) (0.48e0.98) (0.38e0.88) 0.83 0.51 0.75 0.51 0.68 0.49 0.86 0.86 0.56 0.51 0.68 0.58 0.75
(0.56e1.00) (0.26e0.76) (0.51e0.99) (0.26e0.76) (0.44e0.92) (0.24e0.74) (0.61e1.00) (0.61e1.00) (0.31e0.81) (0.24e0.78) (0.44e0.92) (0.31e0.85) (0.50e1.00)
0.77 (0.53e1.00) 0.68 (0.44e0.92) 0.63(0.32e0.94) 0.73 (0.49e0.97) 0.67 (0.34e1.00) 0.72 (0.45 0.99) 0.36 0.86 0.63 0.78 0.79 0.73 0.53 0.42 0.73
(0.03e0.69) (0.51e1.00) (0.26e1.00) (0.41e1.00) (0.42e1.00) (0.38e1.00) (0.28e0.78) (0.15e0.69) (0.38e1.00)
0.65 (0.30e1.00) 0.91 (0.64e1.00) 0.74 (0.47e1.00) 0.89 0.66 0.70 0.75 0.66
(0.65e1.00) (0.35e0.97) (0.48e0.92) (0.53e0.97) (0.44e0.88)
0.83 (0.46e1.00) 0.46 (0.30e0.62) 0.78 (0.53e1.00) 0.83 (0.56e1.00) 0.72 (0.47e0.97) (continued on next page)
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Table 2 (continued) SCQ-LBP item (number of participants)
Kappa (95% CI)
Method of getting to sleep once woken (25) Type of bed (30) Presence of constant symptoms (30) Presence of stiffness in the morning (30) Duration for stiffness to ease (24)
0.73 1.00 0.43 0.61
Weighted Kappa (95% CI)
Mean difference (SD)
(0.44e1.00) (0.65e1.00) (0.43e0.08) (0.26e0.96) 0.78 (0.51e1.00)
Moderate agreement or above shown in bold, CI ¼ confidence interval.
from the SCQ-LBP including standing, erect sitting, sit to stand and cough/sneeze. The validity of subjective complaints whether measured by self administered questionnaire or interview can be affected by poor participant recall (Feine et al., 1998; Dawson et al., 2002). It is self-evident that the measurement of subjective complaints when observed in real time eliminates issues with recall. Real time measurement of subjective complaints was therefore regarded as a suitable reference standard by which concurrent validity of items from the self administered SCQLBP could be tested. At least moderate agreement was demonstrated in five of the seven items evaluated providing evidence for concurrent validity, however, the confidence intervals (CIs) were significantly lower than for the other comparisons made. The results of this component of the study therefore provide preliminary evidence for the concurrent validity of the SCQ-LBP and further research is indicated. Physiotherapists frequently measure subjective complaints by interview (McKenzie et al., 2003; Maitland, 2005). When investigating the value of a self administered questionnaire, it could be argued that the absence of a physiotherapist, and the
Table 3 Concurrent validity of the SCQ-LBP (initial SAePO). SCQ-LBP item
Kappa (95% CI)
Weighted Kappa (95% CI)
Aggravating factors Onset of symptoms 0.54 while standing (29) Duration of standing 0.59 limited by symptoms (28) Onset of symptoms 0.31 while erect sitting (29) Duration of erect 0.40 sitting limited by symptoms (28) Symptoms aggravated 0.35 by sitting to standing (30) Components of sit to stand 0.67 (0.32e1.00) that aggravate symptoms (25) Symptoms aggravated 0.49 by cough/sneeze (28)
(0.32e0.76) (0.35e0.83) (0.11e0.51) (0.15e0.65)
(0.13e0.57)
(0.25e0.73)
PO ¼ physiotherapist observed, moderate agreement or above shown in bold, CI ¼ confidence interval.
resultant unavailability of question clarification, might result in a relative reduction in the accuracy of information obtained. The current study therefore evaluated the agreement between the SA and PA in order to ascertain whether the SCQ-LBP was equally valid in a self administered format. There were minimal differences in the participant responses between the SA and PA. These results suggest that the self administered SCQ-LBP could be useful for future clinical research into the classification of LBP particularly given the moderate levels of reliability demonstrated. The questionnaire could be distributed by post or online, thereby minimising participant inconvenience and loss to follow up. Evidence for the face validity of the SCQ-LBP was provided by the initial SA-PA comparisons in this study. The face validity of the SCQ-LBP is further strengthened given the common usage of the questionnaire items in physiotherapy practice (McKenzie et al., 2003; Maitland, 2005) as well as in much of the large body of research currently being published in the area of LBP classification (Ford et al., 2007). However, most of the classification systems currently being investigated do not have a comprehensive and reliable list of subjective complaints that can be measured in a self administered format. Further research is required on the concurrent validity of the SCQ-LBP items, however, we believe that given substantial reliability and face validity, the SCQ-LBP in its current form has the potential to make a significant contribution to future classification research. Despite these positive findings, a number of items were found to have lower levels of agreement. One of the aims of the physiotherapy clinical interview is to obtain a description of the response to activities/ positions that aggravate symptoms. This usually includes the duration of the activity or position until symptom onset, and the duration upon which the severity of symptoms necessitate cessation of the activity or position; also known as P2 (Maitland, 2005). In the piloting of the SCQ-LBP, eight out of 13 participants experienced difficulty understanding the wording regarding P2. The wording for these items concerning P2 was modified as part of the SCQ-LBP development. In spite of these changes,
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J.J. Ford et al. / Manual Therapy 14 (2009) 283e291 Table 4 Face validity of the SCQ-LBP (initial SAePA). SCQ-LBP item (number of participants)
Kappa (95% CI)
Pain drawing item Area of symptoms (30) Number of symptom descriptors (30) Presence of leg pain (30) Presence of dermatomal symptoms (30) Presence of distal paraesthesia (30)
0.85 (0.50e1.00) 0.79 (0.44e1.00) 0.78 (0.43e1.00)
Symptom details Presence of pins and needles (30) Area of most severe pain (24) Presence of foot drop (30) Lumbar symptoms deep or superficial (29) Leg symptoms deep or superficial (30) Symptom relationship (30)
0.59 0.78 1.00 0.51 0.65 0.65
(0.24e0.94) (0.49e1.00) (0.65e1.00) (0.16e0.86) (0.41e0.89) (0.40e0.90)
0.39 (0.06e0.72) 0.56 (0.29e0.83)
Easing factors Whether standing eases symptoms (30) Whether sitting eases symptoms (30) Whether sitting in a couch eases symptoms (30) Whether walking eases symptoms (29) Whether lying supine eases symptoms (30) Whether crook lying eases symptoms (30) Whether lying on the sore side eases symptoms (29) Whether lying on the good side eases symptoms (28) Whether lying prone eases symptoms (29)
0.52 0.67 0.63 0.72 0.73 0.71 0.47 0.23 0.75
History of over the past three days Time of day when symptoms worst (29) Presence of trouble getting to sleep (30) Presence of waking at night (30) Reason for waking at night (30)
Mean difference (SD)
0.50 (3.01) 0.10 (0.84)
Aggravating factors Onset of symptoms while walking (29) Duration of walking limited by symptoms (28) Onset of symptoms while standing (28) Duration of standing limited by symptoms (27) Onset of symptoms while erect sitting (29) Duration of erect sitting limited by symptoms (28) Onset of symptoms while slumped sitting (29) Duration of slumped sitting limited by symptoms (29) Onset of symptoms while lying supine (29) Duration of lying supine limited by symptoms (28) Onset of symptoms while lying prone (29) Duration of lying prone limited by symptoms (27) Symptoms aggravated by getting into car (29) Components of getting into car that aggravate (24) Symptoms aggravated by sitting to standing (30) Components of sit to stand that aggravate symptoms (28) Symptoms aggravated by cough/sneeze (30) Presence of symptoms worse on one side (30) Most comfortable side to lie on (30)
History of symptoms Whether current symptoms are the first episode (30) Duration of current symptoms (29) Number of episodes of symptoms (30) Time from first episode of symptoms (29) Whether symptoms chronic or recurrent (30) Mechanism of injury for current symptoms (29) Time of onset of current symptoms (30) Behaviour of current symptoms after onset (29) History of manual handling work (29)
Weighted Kappa (95% CI)
0.68 0.42 0.72 0.63 0.43 0.38 0.71 0.47 0.35 0.19 0.51 0.35 0.41
(0.43e0.93) (0.17e0.67) (0.48e0.96) (0.38e0.88) (0.19e0.67) (0.13e0.63) (0.47e0.95) (0.23e0.71) (0.10e0.60) (0.06e0.44) (0.27e0.75) (0.10e0.60) (0.16e0.66)
0.83 (0.59e1.00) 0.57 (0.33e0.81) 0.60 (0.29e0.91) 0.58 (0.34e0.82)
(0.17e0.87) (0.32e1.00) (0.30e0.96) (0.37e1.00) (0.38e1.00) (0.38e1.00) (0.22e0.72) (0.02e0.48) (0.38e1.00)
0.65 (0.30e1.00) 0.94 0.74 0.76 0.65 0.75 0.75 0.48
(0.69e1.00) (0.49e0.99) (0.52e1.00) (0.36e0.94) (0.53e0.97) (0.53e0.97) (0.26e0.70)
0.47 0.82 0.75 0.62
(0.31e0.63) (0.57e1.00) (0.50e1.00) (0.37e0.87)
0.81 (0.44e1.00)
(continued on next page)
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Table 4 (continued) SCQ-LBP item (number of participants) Method of getting to sleep once woken (29) Type of bed (30) Presence of constant symptoms (30) Presence of stiffness in the morning (30) Duration for stiffness to ease (24)
Kappa (95% CI)
Weighted Kappa (95% CI)
Mean difference (SD)
0.76 (0.51e1.00) 1.00 (0.65e1.00) 0.79 (0.44e1.00) 0.61 (0.26e0.96) 0.73 (0.46e1.00)
Moderate agreement or above shown in bold, CI ¼ confidence interval.
relatively lower levels of agreement and associated wider CIs were found in the initial SAeretest SA and initial SAePA comparisons regarding P2 for aggravating factors. The questions regarding the effect of the lying position on symptoms also yielded consistently lower levels of agreement and wider CIs in the initial SAeretest SA and initial SAePA comparisons. This was particularly the case regarding items describing the effect of unilateral symptoms on lying in different positions. Conceptually the principles of P2 and the effect of lying may be too complex in a self administered format for use with the population participating in this study. Caution therefore needs to be exercised when including these items in future clinical research. 4.1. Limitations of the study The population sampled for the current study was primarily those with chronic compensable LBP and further research is required to determine the external validity of the SCQ-LBP in relation to acute and noncompensable LBP populations. Some of the data show relatively modest levels of agreement with wide CIs. It is possible that this was influenced by spontaneous change in the participant’s condition (not detected by the analysis of disability data) or low sample size. Future research on the SCQLBP needs to consider these factors in the planning stage. 5. Conclusion The SCQ-LBP was developed for the purpose of providing a measurement tool for subjective complaints in the classification of LBP. The testeretest reliability of the self administered SCQ-LBP was established as well as preliminary evidence for the concurrent validity of selected items compared with an acceptable reference standard. Moderate agreement between the SA with the PA demonstrate that subjective complaints information can be measured with similar levels of agreement using a self administered format as compared to a physiotherapy interview. The SCQ-LBP may be a useful tool for future research into the classification of LBP. Further research
is required to replicate these findings with larger sample sizes as well as in different populations to investigate external validity. Appendix A. Supplementary data Supplementary data associated with this article can be found in the online version, at doi:10.1016/ j.math.2008.02.010. References Anastasi A, Urbina S. Psychological testing. 7th ed. New Jersey: Prentice Hall; 1997. Bertilson BC, Bring J, Sjoblom A, et al. Inter-examiner reliability in the assessment of low back pain (LBP) using the KirkaldyWillis classification (KWC). European Spine Journal 2006;15: 1695e703. Biering-Sorensen F, Hilden J. Reproducibility of the history of lowback trouble. Spine 1984;9:280e6. Bland J, Altman D. Statistical methods for assessing agreement between two methods of clinical measurement. The Lancet 1986;1:307e10. Boissonnault W, Di Fabio R. Pain profile of patients with low back pain referred to physical therapy. Journal of Orthopedic and Sports Physical Therapy 1996;24:180e91. Borkan J, Cherkin D. An agenda for primary care research on low back pain. Spine 1996;21:2880e4. Burdorf A, Laan J. Comparison of methods for the assessment of postural load on the back. Scandinavian Journal of Work and Environmental Health 1991;17:425e9. Clare HA, Adams R, Maher CG. Reliability of McKenzie classification of patients with cervical or lumbar pain. Journal of Manipulative and Physiological Therapeutics 2005;28:122e7. Dankaerts W, O’Sullivan PB, Straker LM, et al. The inter-examiner reliability of a classification method for non-specific chronic low back pain patients with motor control impairment. Manual Therapy 2006;11:28e39. Dawson EG, Kanim LEA, Sra P, et al. Low back pain recollection versus concurrent accounts: outcomes analysis. Spine 2002;27: 984e93. Delitto A, Erhard R, Bowling R. A treatment-based classification approach to low back syndrome: identifying and staging patients for conservative treatment. Physical Therapy 1995;75:470e89. Feine J, Lavigne G, Dao T, Morin C, Lund J. Memories of chronic pain and perceptions of relief. Pain 1998;77:137e41. Ford J, Story I, O’Sullivan P, et al. Classification systems for low back pain: a review of the methodology for development and validation. Physical Therapy Reviews 2007;12:33e42. Fritz JM, Brennan GP, Clifford SN, et al. An examination of the reliability of a classification algorithm for subgrouping patients with low back pain. Spine 2006;31:77e82.
J.J. Ford et al. / Manual Therapy 14 (2009) 283e291 Heiss DG, Fitch DS, Fritz JM, et al. The interrater reliability among physical therapists newly trained in a classification system for acute low back pain. Journal of Orthopedic and Sports Physical Therapy 2004;34:430e9. Kopec J, Esdaile J, Abrahamowicz M, et al. The Quebec back pain disability scale: measurement properties. Spine 1995;20:141e52. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33:159e74. Mann N, Brown M, Hertz D, Enger I, Tompkins J. Initial-impression diagnosis using low-back pain patients pain drawings. Spine 1993;18:41e53. Maitland G. Maitland’s vertebral manipulation. 7th ed. Philadelphia: Elsevier; 2005. Margolis R, Tait R, Krause S. A rating system for use with patient pain drawings. Pain 1986;24:57e65. McKenzie AR, May S, McKenzie R. The lumbar spine: mechanical diagnosis and therapy. 2nd ed. Orthopaedic Physical Therapy Products; 2003. Ohnmeiss D, Vanharanta H, Guyer R. The association between pain drawings and computed tomographic/discographic pain responses. Spine 1995;20:729e33. Parker H, Wood P, Main C. The use of the pain drawing as a screening measure to predict psychological distress in chronic low back pain. Spine 1995;20:236e43. Petersen T, Olsen S, Laslett M, et al. Inter-tester reliability of a new diagnostic classification system for patients with non-specific low back pain. Australian Journal of Physiotherapy 2004;50:85e94. Petersen T. Classification of non-specific low back pain: a review of the literature on classification systems relevant to physiotherapy. Physical Therapy Reviews 1999;4:265e81.
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Portney L, Watkins M. Foundations of clinical research: applications to practice. 1st ed. Norwalk: Appleton and Lange; 1993. Rankine J, Fortune D, Hutchison S, Hughes D, Main C. Pain drawings in the assessment of nerve root compression: a comparative study with lumbar spine magnetic resonance imaging. Spine 1998;23:1668e76. Riddle D. Classification and low back pain: a review of the literature and critical analysis of selected systems. Physical Therapy 1998; 78:708e37. Roach K, Brown M, Dunigan K, Kusek C, Walas M. Testeretest reliability of a low back pain questionnaire. Physical Therapy 1994; 74:S56. Roach K, Brown M, Randi D, Delaney K, Lipprandt H, Rangelli D. The sensitivity and specificity of pain response to activity and position in categorizing patients with low back pain. Physical Therapy 1997;77:730e7. Roach K, Brown M, Ricker E, Altenburger P, Tompkins J. The use of patient symptoms to screen for serious back problems. Journal of Orthopedic and Sports Physical Therapy 1995;21:2e6. Rucker K, Mezler H, Kregel J. Standardization of chronic pain assessment: a multi-perspective approach. The Clinical Journal of Pain 1996;12:94e110. Uden A, Astrom M, Bergenudd H. Pain drawings in chronic back pain. Spine 1988;13:389e92. Uden A, Landin L. Pain drawing and myelography in sciatic pain. Clinical Orthopaedics and Related Research 1987;216:125e30. Walsh K, Coggon D. Reproducibility of histories of low-back pain obtained by self-administered questionnaire. Spine 1991;16:1075e7. Weiner D, Peterson B, Keefe F. Evaluating persistent pain in long term care residents: what role for pain maps? Pain 1998;76:249e57.
Manual Therapy 14 (2009) 283e291 www.elsevier.com/math
Original Article
The testeretest reliability and concurrent validity of the Subjective Complaints Questionnaire for low back pain Jon Joseph Ford a,*, Ian Story b, Joan McMeeken a a
School of Physiotherapy, The University of Melbourne, Parkville, Victoria 3010, Australia b Faculty of Health and Behavioural Science, Deakin University, Australia
Received 25 August 2005; received in revised form 6 February 2008; accepted 27 February 2008
Abstract Physiotherapists commonly record detailed patient information regarding subjective complaints for low back pain (LBP), particularly to assist in the process of classifying patients into specific subgroups. A self-administered Subjective Complaints Questionnaire for LBP (SCQ-LBP) measuring such information was developed for the purposes of future clinical research, particularly in the area of LBP classification. The development comprised literature review, feedback from experienced physiotherapists and pilot questionnaire testing in a patient population. Testeretest reliability of the questionnaire in a self administered format as well as concurrent validity against a suitable reference standard was evaluated. The agreement between the self administered questionnaire compared to when administered by a physiotherapist was also tested as the latter method is the most common form of retrieving subjective complaints in clinical practice. Thirty participants with LBP were recruited and at least moderate testeretest reliability was demonstrated in 56 of the 57 self administered questionnaire items. Preliminary evidence was found supporting the concurrent validity of selected items. At least moderate agreement was demonstrated in 51 of the 57 items when comparing between the self administered and physiotherapist administered conditions. The questionnaire is a useful tool for collecting subjective complaints information, particularly for clinical research on the classification of LBP, however, further research regarding validity is required. Ó 2008 Elsevier Ltd. All rights reserved. Keywords: Back pain; Classification; Questionnaire; Validity
1. Introduction Subjective complaints, reported by the sufferer in spoken or written form, are commonly documented as part of the standard assessment of low back pain (LBP). In clinical practice physiotherapists use a detailed subjective complaints interview to retrieve large amounts of * Corresponding author. Tel.: þ61 03 9607 3051; fax: þ61 03 9670 3080. E-mail address: [email protected] (J.J. Ford). 1356-689X/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.math.2008.02.010
information regarding the nature of symptoms, aggravating/easing factors, 24 h symptom behaviour, history and special questions (McKenzie et al., 2003; Maitland, 2005). This subjective complaints information can then be used to classify patients into subgroups that receive specific treatment (Delitto et al., 1995; McKenzie et al., 2003; Maitland, 2005). A common clinical example of using subjective complaints in the classification of LBP is the identification of an inflammatory cause of symptoms using criteria such as constancy of pain and a perception of stiffness in the injured area lasting at least 1 h after
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waking. Such patients may respond more effectively to anti-inflammatory modalities rather than treatment directed at a mechanical cause of symptoms (McKenzie et al., 2003; Maitland, 2005). Improved classification of LBP has been described as a high research priority by an esteemed international working group (Borkan and Cherkin, 1996). However, a number of review papers show that published classification systems have yet to demonstrate adequate reliability or validity and that methodological problems are common (Riddle, 1998; Petersen, 1999; Ford et al., 2007). One of the issues in the literature evaluating classification systems for LBP is the use of unreliable or poorly validated measurement tools for collecting data relevant to the classification process (Riddle, 1998; Petersen, 1999; Ford et al., 2007). There is relatively little research into reliable and valid methods of measuring subjective complaints. Only one study has reported on a comprehensive tool for measuring subjective complaints in individuals with LBP. The questionnaire developed included items such as the nature of symptoms, aggravating factors and history and variable testeretest reliability was found for the different questionnaire components (Walsh and Coggon, 1991). A 1-year retest period was used to minimise memory effects, however, a potential adverse consequence of this approach on the results may have been a spontaneous change in the nature and/or severity of the LBP. In addition the details of questionnaire wording and scoring were not described. The Multi-perspective Multi-dimensional Pain Assessment Protocol has been developed as a self administered questionnaire for chronic pain. It contains items on patient details, nature of symptoms, aggravating and easing factors, 24 h behaviour and history (Rucker et al., 1996). The questionnaire was developed with a view to maximising content validity and on evaluation, acceptable reliability and validity were demonstrated. However, the items in the questionnaire were not sufficiently comprehensive or specific to be used for the assessment of LBP patients when compared to accepted methods currently in widespread clinical use by physiotherapists (McKenzie et al., 2003; Maitland, 2005). A number of recent papers have evaluated the reliability of a variety of classification systems, however, typically subjective complaints are either poorly defined or insufficiently comprehensive to reflect the clinical practice of physiotherapists (Heiss et al., 2004; Petersen et al., 2004; Bertilson et al., 2006; Dankaerts et al., 2006; Fritz et al., 2006). One paper has been published investigating the reliability of the McKenzie classification system using a specific assessment form that included subjective complaints information (Clare et al., 2005). However, the ability of the form itself to reliably retrieve information from patients on retesting was not evaluated.
On the basis of this insufficient literature, there are limited options for clinical researchers wishing to use a reliable and valid questionnaire that comprehensively assesses subjective complaints for LBP. The aims of this study were therefore to develop a questionnaire for the self administered measurement of subjective complaints in LBP, and to evaluate its testeretest reliability and concurrent validity. Self administered questionnaires are an efficient method of data collection in clinical research. The purpose of this study was not to investigate the value of a particular classification system for LBP, but rather to establish a reliable and valid tool for the measurement of subjective complaints for use in future clinical research, particularly in the area of classification.
2. Method 2.1. Questionnaire development The critical components of our Subjective Complaints Questionnaire for low back pain (SCQ-LBP) comprised nature of symptoms, aggravating and easing factors, 24 h behaviour, and history. These components were predetermined based on clinical approaches commonly used by physiotherapists (McKenzie et al., 2003; Maitland, 2005). The specific questionnaire items were developed in four stages: literature review, operational definition of questionnaire items, peer review of the questionnaire, and pilot testing on individuals with LBP. A literature review was performed using the Current Contents database from years 1970 to 2003 inclusive. This database is a multidisciplinary current awareness web resource providing access to complete bibliographic information from over 8000 of the world’s leading scholarly journals. It includes databases with extensive coverage in the social and behavioural sciences as well as clinical medicine. Key words for the search were ‘‘back pain and validity’’ combined in separate searches with ‘‘subjective’’, ‘‘history’’ and ‘‘questionnaire’’. Full text copies of all identified papers were then retrieved. Further papers were unearthed by cross-referencing from the retrieved papers. On review of this literature, pain drawings as a measure of the nature of symptoms were found to be reliable (Margolis et al., 1986; Uden et al., 1988; Weiner et al., 1998) and some evidence of validity as a tool for classification was demonstrated (Uden and Landin, 1987; Mann et al., 1993; Ohnmeiss et al., 1995) although this latter conclusion has been disputed (Rankine et al., 1998). Preliminary evidence was found for the reliability and validity of a self administered questionnaire measuring aggravating factors in LBP (Roach et al., 1994, 1995, 1997). Studies evaluating the reliability or validity of
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24 h symptom behaviour had not been published for LBP. The two studies evaluating the reliability and validity of questionnaires measuring the history of LBP showed poor results (Biering-Sorensen and Hilden, 1984; Burdorf and Laan, 1991) potentially due to the influence of recall issues. Given the limited validation of many of the predefined critical subjective complaints components, items for our SCQ-LBP were chosen from the above literature if reliability and/or preliminary validity had been demonstrated (Margolis et al., 1986; Uden et al., 1988; Roach et al., 1994, 1995, 1997; Weiner et al., 1998). Where no such evidence existed, questionnaire items were selected from publications where subjective complaints were well described, either from the above literature or the descriptive literature on LBP (Boissonnault and Di Fabio, 1996; McKenzie et al., 2003; Maitland, 2005) and chronic injury (Rucker, 1996). Following the literature review an initial draft version of the SCQ-LBP was developed and distributed to two senior coordinators of the musculoskeletal physiotherapy postgraduate program from Universities in Victoria, Australia, and three physiotherapists with at least 5 years clinical experience working predominantly with chronic LBP. The feedback received was primarily in relation to scoring issues and consistency of wording between items. The second draft of the SCQ-LBP was self administered to 13 individuals with chronic LBP. Further modification to the SCQ-LBP was made to items where consistent feedback was given resulting in the final version of the SCQ-LBP (see Manual Therapy website).
2.2. Reliability and concurrent validity of the SCQ-LBP Participants were recruited from patients referred to physiotherapy private practices in Melbourne, Australia. Inclusion criteria were a primary problem of LBP, aged over 18 years, no signs or symptoms of serious nonmusculoskeletal pathology, and literacy in spoken and written English. In order to evaluate testeretest reliability in a self administered condition (SA), the SCQ-LBP was completed by participants twice within a period of 24e48 h. Under this condition, participants were given the questionnaire to complete without assistance. Reliability was tested only for the SA as our aim was to develop a reliable and valid measure that for pragmatic reasons in relation to clinical research was self administered. In order to evaluate concurrent and face validity participants performed specific items from the SCQ-LBP whilst being observed by physiotherapists (PO) and in
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also completed the full questionnaire in a physiotherapist administered condition (PA). Concurrent validity is a research design used to evaluate the ability of a newly developed measure to predict the results of an existing measure that represents an irrefutable truth or criterion standard (Portney and Watkins, 1993; Anastasi and Urbina, 1997). Often the newer measure is more convenient, less invasive or less costly than the criterion standard. However, in practice such absolute measures are rarely available and a more appropriate comparison is often with a reference standard that is the best available measure of truth (Portney and Watkins, 1993). In the current study the concurrent validity of the self administered SCQ-LBP (as a more convenient and cost effective measure for clinical research) was evaluated for its ability to predict the results of the physiotherapist observed condition (PO) (the reference standard). In the PO, the participant was asked to perform specific aggravating factors from the SCQ-LBP that could be replicated in a clinical environment such as sitting tolerance. The physiotherapist observed and questioned the participant regarding pain response according to a predetermined protocol in order to standardise measurement procedures. Time related variables were measured using a stopwatch. For example, time to onset of lumbar symptoms when in erect sitting, and time to the point where erect sitting could no longer be tolerated were measured. These time values were then compared to the response for the same items in the SA. In the PA a physiotherapist read each questionnaire item to the participant and filled in the participant responses. Clarification regarding questionnaire items was provided by the physiotherapist to the participant as required, and in accordance with a standardised protocol. The PA was intended to replicate the current clinical method of retrieving subjective complaints by physiotherapists (Maitland, 2005). Rather than representing an adequate reference standard, the SA was compared to the PA to evaluate whether the role of practitioner clarification was necessary in a clinical research setting. This comparison could therefore be considered an investigation of the face validity of the self administered SCQ-LBP (Portney and Watkins, 1993; Anastasi and Urbina, 1997). Each participant completed four administrations of the SCQ-LBP (initial SA, retest SA, PO and PA) according to one of six predetermined combinations of possible order, sequentially applied to each participant, to eliminate any effect of the order of administration on the results. To minimise any 24 h variation in the participants’ LBP, all data collection occurred at the same time of day. In addition, to evaluate spontaneous change between data collection sessions the Quebec Back Pain Disability Scale (Kopec et al., 1995) was completed at each questionnaire administration including the PO.
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2.3. Analysis Calculation of agreement was made on comparisons between the following SCQ-LBP conditions: initial SAeretest SA, initial SAePA and initial SAePO. Kappa statistics were used for all data with four or less response categories. For response categories of five or more weighted Kappa was calculated. Moderate agreement was defined as being greater than or equal to 0.4, and substantial agreement greater than or equal to 0.6 (Landis and Koch, 1977). For interval data mean differences and standard deviations (SDs) were calculated for each condition comparison (Bland and Altman, 1986).
3. Results Thirty participants provided informed consent and completed the data collection. There were no withdrawals from the study. The demographic and clinical characteristics of the sample are presented in Table 1. A one-way repeated measures analysis of variance found no significant within participant difference in the Quebec Back Pain Disability Scale scores across the measurement sessions (df ¼ 3.26, F ¼ 0.42, p ¼ 0.66). This indicates that spontaneous change over Table 1 Demographic and clinical characteristics for each group given as the mean (SD) or the number (%). Characteristic
Mean/SD (N ¼ 30)
Age (years)
42 (9.3)
Gender Male Female
Number/ percentage (N ¼ 30)
11 (37%) 19 (63%)
Weight (kg)
79 (15)
Height (cm)
175 (11)
Education Complete primary Complete secondary Complete tertiary
11 (37%) 10 (33%) 9 (30%)
Compensable Yes No
30 (100%) 0 (0%)
Duration of LBP 2e3 months 4e6 months 7e12 months More than 12 months
1 1 5 23
Past history of lumbar surgery Yes No
6 (20%) 24 (80%)
(3%) (3%) (17%) (77%)
time had no significant effect on disability and is therefore unlikely to have influenced the level of agreement observed. Mean differences and SDs were calculated for the pain drawing data and the level of agreement determined by judgement (Bland and Altman, 1986). The area score method (Parker et al., 1995) was used to count the number of grids where symptoms were marked. The maximum number of grids possible to mark was 264. The mean difference between the area scores in the initial SAeretest SA comparison was 0.60 (SD 6.56) and only five of the 30 participants had a difference of over five points. Higher levels of agreement were demonstrated on the initial SAePA comparison. The maximum number of symptoms descriptors was six on the pain drawing and the initial SAeretest SA comparison difference was 0.07 (SD 1.04). Only four of the 30 participants had a difference of over one point. Similar figures on the initial SAe PA comparison was observed. It was judged that sufficient agreement was observed on the initial SAe retest SA and initial SAePA comparisons for both the pain drawing area score and number of symptom descriptors. Substantial agreement was therefore found in 44 out of 57 items on the initial SAeretest SA comparisons. Moderate agreement was found in a further 12 items, with one item having less than moderate agreement. The results of the testeretest reliability of the SCQ-LBP in the SA are summarised in Table 2. Substantial agreement was found in one out of seven items on the initial SAePO comparisons with moderate agreement in a further four items. Two items had less than moderate agreement. The results of this comparison are presented in Table 3. Substantial agreement was found in 37 out of 57 items on comparison between the initial SAePA with moderate agreement in a further 14 items. However, six items had less than moderate agreement. These results are presented in Table 4.
4. Discussion The SCQ-LBP was developed using the methodology of literature review, review from a panel of experienced physiotherapists, and pilot testing on a sample of individuals with LBP. The testeretest reliability of the developed questionnaire was acceptable. Specifically, at least moderate agreement was found on 56 of the total 57 items on testeretest of the SCQ-LBP in the SA. The concurrent validity of the SCQ-LBP was examined by a comparison of the SA to the PO. In the PO each participant was tested in real time for tolerances to performing specific aggravating factors
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J.J. Ford et al. / Manual Therapy 14 (2009) 283e291 Table 2 Testeretest reliability of the SCQ-LBP (initial SAeretest SA). SCQ-LBP item (number of participants)
Kappa (95% CI)
Pain drawing item Area of symptoms (30) Number of symptom descriptors (30) Presence of leg pain (30) Presence of dermatomal symptoms (30) Presence of distal paraesthesia (30)
0.55 (0.20e0.90) 0.66 (0.31e1.00) 0.57 (0.22e0.92)
Symptom details Presence of pins and needles (29) Area of most severe pain (23) Presence of foot drop (29) Lumbar symptoms deep or superficial (29) Leg symptoms deep or superficial (29) Symptom relationship (29)
0.73 0.78 1.00 0.72 0.73 0.63
Aggravating factors Onset of symptoms while walking (28) Duration of walking limited by symptoms (27) Onset of symptoms while standing (27) Duration of standing limited by symptoms (29) Onset of symptoms while erect sitting (28) Duration of erect sitting limited by symptoms (29) Onset of symptoms while slumped sitting (29) Duration of slumped sitting limited by symptoms (29) Onset of symptoms while lying supine (29) Duration of lying supine limited by symptoms (28) Onset of symptoms while lying prone (29) Duration of lying prone limited by symptoms (27) Symptoms aggravated by getting into car (28) Components of getting into car that aggravate (24) Symptoms aggravated by sitting to standing (30) Components of sit to stand that aggravate symptoms (29) Symptoms aggravated by cough/sneeze (30) Presence of symptoms worse on one side (30) Most comfortable side to lie on (29) Easing factors Whether standing eases symptoms (29) Whether sitting eases symptoms (29) Whether sitting in a couch eases symptoms (29) Whether walking eases symptoms (29) Whether lying supine eases symptoms (29) Whether crook lying eases symptoms (29) Whether lying on the sore side eases symptoms (29) Whether lying on the good side eases symptoms (27) Whether lying prone eases symptoms (29) History of symptoms Whether current symptoms are the first episode (30) Duration of current symptoms (29) Number of episodes of symptoms (28) Time from first episode of symptoms (28) Whether symptoms chronic or recurrent (28) Mechanism of injury for current symptoms (28) Time of onset of current symptoms (29) Behaviour of current symptoms after onset (28) History of manual handling at work (28) History of over the past three days Time of day when symptoms worst (29) Presence of trouble getting to sleep (29) Presence of waking at night (29) Reason for waking at night (28)
Weighted Kappa (95% CI)
Mean difference (SD) 0.60 (5.54) 0.07 (1.05)
(0.38e1.00) (0.47e1.00) (0.63e1.00) (0.43e1.00) (0.48e0.98) (0.38e0.88) 0.83 0.51 0.75 0.51 0.68 0.49 0.86 0.86 0.56 0.51 0.68 0.58 0.75
(0.56e1.00) (0.26e0.76) (0.51e0.99) (0.26e0.76) (0.44e0.92) (0.24e0.74) (0.61e1.00) (0.61e1.00) (0.31e0.81) (0.24e0.78) (0.44e0.92) (0.31e0.85) (0.50e1.00)
0.77 (0.53e1.00) 0.68 (0.44e0.92) 0.63(0.32e0.94) 0.73 (0.49e0.97) 0.67 (0.34e1.00) 0.72 (0.45 0.99) 0.36 0.86 0.63 0.78 0.79 0.73 0.53 0.42 0.73
(0.03e0.69) (0.51e1.00) (0.26e1.00) (0.41e1.00) (0.42e1.00) (0.38e1.00) (0.28e0.78) (0.15e0.69) (0.38e1.00)
0.65 (0.30e1.00) 0.91 (0.64e1.00) 0.74 (0.47e1.00) 0.89 0.66 0.70 0.75 0.66
(0.65e1.00) (0.35e0.97) (0.48e0.92) (0.53e0.97) (0.44e0.88)
0.83 (0.46e1.00) 0.46 (0.30e0.62) 0.78 (0.53e1.00) 0.83 (0.56e1.00) 0.72 (0.47e0.97) (continued on next page)
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Table 2 (continued) SCQ-LBP item (number of participants)
Kappa (95% CI)
Method of getting to sleep once woken (25) Type of bed (30) Presence of constant symptoms (30) Presence of stiffness in the morning (30) Duration for stiffness to ease (24)
0.73 1.00 0.43 0.61
Weighted Kappa (95% CI)
Mean difference (SD)
(0.44e1.00) (0.65e1.00) (0.43e0.08) (0.26e0.96) 0.78 (0.51e1.00)
Moderate agreement or above shown in bold, CI ¼ confidence interval.
from the SCQ-LBP including standing, erect sitting, sit to stand and cough/sneeze. The validity of subjective complaints whether measured by self administered questionnaire or interview can be affected by poor participant recall (Feine et al., 1998; Dawson et al., 2002). It is self-evident that the measurement of subjective complaints when observed in real time eliminates issues with recall. Real time measurement of subjective complaints was therefore regarded as a suitable reference standard by which concurrent validity of items from the self administered SCQLBP could be tested. At least moderate agreement was demonstrated in five of the seven items evaluated providing evidence for concurrent validity, however, the confidence intervals (CIs) were significantly lower than for the other comparisons made. The results of this component of the study therefore provide preliminary evidence for the concurrent validity of the SCQ-LBP and further research is indicated. Physiotherapists frequently measure subjective complaints by interview (McKenzie et al., 2003; Maitland, 2005). When investigating the value of a self administered questionnaire, it could be argued that the absence of a physiotherapist, and the
Table 3 Concurrent validity of the SCQ-LBP (initial SAePO). SCQ-LBP item
Kappa (95% CI)
Weighted Kappa (95% CI)
Aggravating factors Onset of symptoms 0.54 while standing (29) Duration of standing 0.59 limited by symptoms (28) Onset of symptoms 0.31 while erect sitting (29) Duration of erect 0.40 sitting limited by symptoms (28) Symptoms aggravated 0.35 by sitting to standing (30) Components of sit to stand 0.67 (0.32e1.00) that aggravate symptoms (25) Symptoms aggravated 0.49 by cough/sneeze (28)
(0.32e0.76) (0.35e0.83) (0.11e0.51) (0.15e0.65)
(0.13e0.57)
(0.25e0.73)
PO ¼ physiotherapist observed, moderate agreement or above shown in bold, CI ¼ confidence interval.
resultant unavailability of question clarification, might result in a relative reduction in the accuracy of information obtained. The current study therefore evaluated the agreement between the SA and PA in order to ascertain whether the SCQ-LBP was equally valid in a self administered format. There were minimal differences in the participant responses between the SA and PA. These results suggest that the self administered SCQ-LBP could be useful for future clinical research into the classification of LBP particularly given the moderate levels of reliability demonstrated. The questionnaire could be distributed by post or online, thereby minimising participant inconvenience and loss to follow up. Evidence for the face validity of the SCQ-LBP was provided by the initial SA-PA comparisons in this study. The face validity of the SCQ-LBP is further strengthened given the common usage of the questionnaire items in physiotherapy practice (McKenzie et al., 2003; Maitland, 2005) as well as in much of the large body of research currently being published in the area of LBP classification (Ford et al., 2007). However, most of the classification systems currently being investigated do not have a comprehensive and reliable list of subjective complaints that can be measured in a self administered format. Further research is required on the concurrent validity of the SCQ-LBP items, however, we believe that given substantial reliability and face validity, the SCQ-LBP in its current form has the potential to make a significant contribution to future classification research. Despite these positive findings, a number of items were found to have lower levels of agreement. One of the aims of the physiotherapy clinical interview is to obtain a description of the response to activities/ positions that aggravate symptoms. This usually includes the duration of the activity or position until symptom onset, and the duration upon which the severity of symptoms necessitate cessation of the activity or position; also known as P2 (Maitland, 2005). In the piloting of the SCQ-LBP, eight out of 13 participants experienced difficulty understanding the wording regarding P2. The wording for these items concerning P2 was modified as part of the SCQ-LBP development. In spite of these changes,
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J.J. Ford et al. / Manual Therapy 14 (2009) 283e291 Table 4 Face validity of the SCQ-LBP (initial SAePA). SCQ-LBP item (number of participants)
Kappa (95% CI)
Pain drawing item Area of symptoms (30) Number of symptom descriptors (30) Presence of leg pain (30) Presence of dermatomal symptoms (30) Presence of distal paraesthesia (30)
0.85 (0.50e1.00) 0.79 (0.44e1.00) 0.78 (0.43e1.00)
Symptom details Presence of pins and needles (30) Area of most severe pain (24) Presence of foot drop (30) Lumbar symptoms deep or superficial (29) Leg symptoms deep or superficial (30) Symptom relationship (30)
0.59 0.78 1.00 0.51 0.65 0.65
(0.24e0.94) (0.49e1.00) (0.65e1.00) (0.16e0.86) (0.41e0.89) (0.40e0.90)
0.39 (0.06e0.72) 0.56 (0.29e0.83)
Easing factors Whether standing eases symptoms (30) Whether sitting eases symptoms (30) Whether sitting in a couch eases symptoms (30) Whether walking eases symptoms (29) Whether lying supine eases symptoms (30) Whether crook lying eases symptoms (30) Whether lying on the sore side eases symptoms (29) Whether lying on the good side eases symptoms (28) Whether lying prone eases symptoms (29)
0.52 0.67 0.63 0.72 0.73 0.71 0.47 0.23 0.75
History of over the past three days Time of day when symptoms worst (29) Presence of trouble getting to sleep (30) Presence of waking at night (30) Reason for waking at night (30)
Mean difference (SD)
0.50 (3.01) 0.10 (0.84)
Aggravating factors Onset of symptoms while walking (29) Duration of walking limited by symptoms (28) Onset of symptoms while standing (28) Duration of standing limited by symptoms (27) Onset of symptoms while erect sitting (29) Duration of erect sitting limited by symptoms (28) Onset of symptoms while slumped sitting (29) Duration of slumped sitting limited by symptoms (29) Onset of symptoms while lying supine (29) Duration of lying supine limited by symptoms (28) Onset of symptoms while lying prone (29) Duration of lying prone limited by symptoms (27) Symptoms aggravated by getting into car (29) Components of getting into car that aggravate (24) Symptoms aggravated by sitting to standing (30) Components of sit to stand that aggravate symptoms (28) Symptoms aggravated by cough/sneeze (30) Presence of symptoms worse on one side (30) Most comfortable side to lie on (30)
History of symptoms Whether current symptoms are the first episode (30) Duration of current symptoms (29) Number of episodes of symptoms (30) Time from first episode of symptoms (29) Whether symptoms chronic or recurrent (30) Mechanism of injury for current symptoms (29) Time of onset of current symptoms (30) Behaviour of current symptoms after onset (29) History of manual handling work (29)
Weighted Kappa (95% CI)
0.68 0.42 0.72 0.63 0.43 0.38 0.71 0.47 0.35 0.19 0.51 0.35 0.41
(0.43e0.93) (0.17e0.67) (0.48e0.96) (0.38e0.88) (0.19e0.67) (0.13e0.63) (0.47e0.95) (0.23e0.71) (0.10e0.60) (0.06e0.44) (0.27e0.75) (0.10e0.60) (0.16e0.66)
0.83 (0.59e1.00) 0.57 (0.33e0.81) 0.60 (0.29e0.91) 0.58 (0.34e0.82)
(0.17e0.87) (0.32e1.00) (0.30e0.96) (0.37e1.00) (0.38e1.00) (0.38e1.00) (0.22e0.72) (0.02e0.48) (0.38e1.00)
0.65 (0.30e1.00) 0.94 0.74 0.76 0.65 0.75 0.75 0.48
(0.69e1.00) (0.49e0.99) (0.52e1.00) (0.36e0.94) (0.53e0.97) (0.53e0.97) (0.26e0.70)
0.47 0.82 0.75 0.62
(0.31e0.63) (0.57e1.00) (0.50e1.00) (0.37e0.87)
0.81 (0.44e1.00)
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Table 4 (continued) SCQ-LBP item (number of participants) Method of getting to sleep once woken (29) Type of bed (30) Presence of constant symptoms (30) Presence of stiffness in the morning (30) Duration for stiffness to ease (24)
Kappa (95% CI)
Weighted Kappa (95% CI)
Mean difference (SD)
0.76 (0.51e1.00) 1.00 (0.65e1.00) 0.79 (0.44e1.00) 0.61 (0.26e0.96) 0.73 (0.46e1.00)
Moderate agreement or above shown in bold, CI ¼ confidence interval.
relatively lower levels of agreement and associated wider CIs were found in the initial SAeretest SA and initial SAePA comparisons regarding P2 for aggravating factors. The questions regarding the effect of the lying position on symptoms also yielded consistently lower levels of agreement and wider CIs in the initial SAeretest SA and initial SAePA comparisons. This was particularly the case regarding items describing the effect of unilateral symptoms on lying in different positions. Conceptually the principles of P2 and the effect of lying may be too complex in a self administered format for use with the population participating in this study. Caution therefore needs to be exercised when including these items in future clinical research. 4.1. Limitations of the study The population sampled for the current study was primarily those with chronic compensable LBP and further research is required to determine the external validity of the SCQ-LBP in relation to acute and noncompensable LBP populations. Some of the data show relatively modest levels of agreement with wide CIs. It is possible that this was influenced by spontaneous change in the participant’s condition (not detected by the analysis of disability data) or low sample size. Future research on the SCQLBP needs to consider these factors in the planning stage. 5. Conclusion The SCQ-LBP was developed for the purpose of providing a measurement tool for subjective complaints in the classification of LBP. The testeretest reliability of the self administered SCQ-LBP was established as well as preliminary evidence for the concurrent validity of selected items compared with an acceptable reference standard. Moderate agreement between the SA with the PA demonstrate that subjective complaints information can be measured with similar levels of agreement using a self administered format as compared to a physiotherapy interview. The SCQ-LBP may be a useful tool for future research into the classification of LBP. Further research
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