- Email: [email protected]
Dash and Boston questionnaire assessment of carpal tunnel syndrome outcome: what is the responsiveness of an outcome questionnaire?
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DASH AND BOSTON QUESTIONNAIRE ASSESSMENT OF CARPAL TUNNEL SYNDROME OUTCOME: WHAT IS THE RESPONSIVENESS OF AN OUTCOME QUESTIONNAIRE? J. R. GREENSLADE, R. L. MEHTA, P. BELWARD and D. J. WARWICK From the Upper Limb Team, Department of Orthopaedics and Research and Development Support Unit, Southampton University Hospital, Southampton, UK
This prospective study evaluates if the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire is an adequately responsive outcome measure in carpal tunnel syndrome by comparing it with the disease-specific Boston questionnaire (BQ). To measure responsiveness (sensitivity to clinical change), 57 patients with a clinical diagnosis of carpal tunnel syndrome completed the DASH and BQ preoperatively and again 3 months after open carpal tunnel decompression. A second group of 31 patients completed the questionnaires in the outpatient clinic and again 2 weeks later to assess test–retest reliability. The time to complete all questionnaires was recorded. Responsiveness of the DASH is comparable with the BQ with standardized response means of 0.66, 1.07 and 0.62 for the DASH, BQ-symptoms and BQ-function, respectively. Test–retest data show both questionnaires are reliable. Mean times to complete questionnaires were 6.8 minutes (DASH) and 5.6 minutes (BQ). This study concludes that the DASH questionnaire is a reliable, responsive and practical outcome instrument in carpal tunnel syndrome. Journal of Hand Surgery (British and European Volume, 2004) 29B: 2: 159–164 Keywords: carpal tunnel release, DASH questionnaire, outcome measures
Katz et al., 1994; Mondelli et al., 2000) and has been validated in other languages (Atroshi et al., 1998; Levine et al., 1993). It comprises two sections, one assessing symptoms such as pain and paraesthesia (BQ symptom severity or BQ-SS), and the second analysing function (BQ-F) in terms of eight day-to-day tasks. A mean score for both symptom severity and functional status is given. The Disability of the Arm, Shoulder and Hand (DASH) questionnaire (Hudak et al., 1996) is designed for use in any upper limb disorder and has been validated in several different languages (Dubert et al., 2001; Germann et al., 1999; Rosales et al., 2002). It has been compared with generic instruments such as the SF-36 (SooHoo et al., 2002), and with outcome measures for the shoulder, elbow, wrist and hand (Beaton et al., 2001; MacDermid et al., 2000; Turchin et al., 1998). It is a 30-item questionnaire with 21 questions concerning function, six symptom severity and three psychosocial factors. Some authors have found disease-specific questionnaires more sensitive to clinical change (Amadio et al., 1996; MacDermid et al., 2000), whilst others have shown the DASH to be comparable to, or better than, joint-specific measures (Beaton et al., 2001). In this study, we aimed to prospectively compare the Boston and DASH questionnaires to measure responsiveness and test–retest reliability. We also aimed to assess their ‘‘practicality’’ for routine use by recording the time taken by the patient to finish each questionnaire and by analysing those incorrectly completed.
INTRODUCTION It is important to assess accurately the outcome of interventions when defining the quality of medical care. Determination of the outcome of carpal tunnel decompression by the operating surgeon is subject to observer bias (Levine et al., 1993) and this bias can be overcome by the use of self-administered questionnaires which address impact on physical function, as well as social and emotional well being. They also have the resource advantage of not requiring input from trained staff during completion. Self-administered questionnaires have superior responsiveness (sensitivity to clinical change) when compared with objective tests in hand surgery such as two-point discrimination, Semmes–Weinstein pressure sensibility, abductor pollicus brevis, grip and pinch strength (Amadio et al., 1996; Atroshi et al., 1999; Katz et al., 1994; MacDermid et al., 2000). Several studies have demonstrated no correlation between ‘‘objective’’ neurophysiological testing and patients’ symptoms following carpal tunnel decompression (Heybeli et al., 2002; Mondelli et al., 2000) and observer-based questionnaires have also been shown to be less responsive than selfadministered questionnaires (Turchin et al., 1998). The Boston questionnaire (BQ) is self-administered (Levine et al., 1993) and is a well-recognized, validated outcome instrument specific for use in carpal tunnel syndrome. It has been compared with many different outcome measures (Amadio et al., 1996; Atroshi et al., 1997–1999; Beaton et al., 2001; Heybeli et al., 2002; 159
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PATIENTS AND METHOD We prospectively followed 88 patients diagnosed with carpal tunnel syndrome at Southampton University Hospitals from March 2002 until September 2002. The study had local Research Ethics Committee approval. Patients were excluded if they had diabetes, thyroid disease, rheumatoid arthritis, gout, radiculopathy of the cervical spine, pregnancy, ipsilateral upper limb pathology requiring surgery or recurrent carpal tunnel syndrome following previous surgery. Decompression was open, by a palmar incision, with a high arm tourniquet. All procedures were performed as a day case under local anaesthetic except for three, which were under general anaesthetic due to patient preference. The procedure was undertaken by several different surgeons of different grade, thus reflecting practice in our unit. Two patient groups were studied. The first was recruited preoperatively on the day of surgery. The DASH and BQ were completed before the operation and a second questionnaire was posted to each patient 3 months after surgery. The second group was recruited to assess reliability. Patients with a diagnosis of carpal tunnel syndrome being listed for decompression answered the questionnaire in the outpatient clinic. Questionnaire completion was repeated 2 weeks later and returned by post. This interval was thought to be long enough to prevent the patient remembering previous answers, but not so long as to allow a significant change in symptom severity. Practicality was compared in both groups by measuring three variables. Firstly, patients recorded completion time of every questionnaire. Secondly, the number of rejected questionnaires due to three or more missed responses was compared. Finally, the total number of missed items for those not rejected (less than three) was noted.
Statistical analysis, methods and techniques The mean preoperative and postoperative scores for DASH, BQ-SS and BQ-F were calculated. For each of these measures the standardized response mean (mean difference between the paired scales divided by the standard deviation of the paired difference, SRM) was calculated. The SRM is a point estimate of the effect measured; 0.2 indicating small, 0.5 indicating moderate and greater than 0.8 large change. A comparison between the preoperative and postoperative scales was performed using analyses of variance techniques and t-tests for continuous data. For categorical data, a chi-squared test was performed. Linear regression analysis was performed to assess the relationship of the percentage change (D) between preoperative and postoperative scales against the independent age. The regression coefficient beta was calculated for age.
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In group 2, a correlation of DASH, BQ-SS and BQ-F between the first and fourteenth days was measured using the Pearson’s correlation coefficient. Reliability coefficients were calculated which is a measure of the relative magnitude of association among the series of measures between the two times.
RESULTS One hundred and eighty-eight patients completed forms preoperatively, but 15 were excluded due to confounding variables (ipsilateral trigger finger release, revision surgery) leaving 173 eligible for the study. One hundred were recruited to group 1 and 73 to group 2. One hundred and twenty-four patients (72%) returned forms by post. Twenty-one forms were excluded due to a delay in their return which may have skewed test–retest data due to disease progression. One patient died during the follow-up period and 14 were excluded due to insufficient questions answered, leaving 57 in group 1 and 31 in group 2. Responsiveness (Group 1) Of the 57 patients who completed questionnaires 90 days (range, 85–100) postoperatively, 16 were men and 41 women (Table 1). Their mean age was 57 (range, 49– 65) years and 59 (range, 53–64) years for men and women, respectively. Figure 2 shows that women had significantly higher DASH scores preoperatively (P=0.012), but this pattern was not observed in the BQ. The postoperative scores did not differ significantly between genders (Table 1). The mean improvement in DASH score 3 months postoperatively was 15 (Table 2). The DASH SRM of 0.66 is marginally higher than the BQ-F SRM of 0.62 indicating higher responsiveness. However, the DASH was less responsive than the BQ-SS, which had a SRM of 1.07. Age was found to correlate negatively with outcome for the DASH and BQ (Fig 1). There was a correlation between preoperative scores and change in score, in that the higher the preoperative score the greater the improvement, and vice versa. This pattern was observed for DASH, BQ-SS and BQ-F (Fig 2). Test–retest reliability (Group 2) Thirty-one patients returned second forms by post 14 (range, 10–16) days after the first form. As anticipated, if there was a low score in the initial assessment then there was also a low score in the re-test. This was also observed with high scores. The mean differences bet-ween test and re-test scores for each individual were not significantly different from zero, and the reliability co-efficients were markedly and consistently high (Table 3 and Fig 3).
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Table 1—DASH, BQ-SS and BQ-F scores compared to gender
(a) Preoperative values DASH BQ-SS BQ-F
Gender
N
Mean score
SD
95% CI
Male Female Male Female Male Female
16 41 16 41 16 41
29 45 2.9 3.1 2.3 2.7
22 21 0.8 0.6 0.9 0.9
17, 39, 2.5, 2.9, 1.8, 2.5,
16 41 16 41 16 41
18 28 1.9 2.0 1.7 2.0
23 25 0.9 1.0 1.0 1.0
6,31 20, 36 1.4, 2.4 1.7, 2.3 1.1, 2.2 1.7, 2.4
(b) Three month postoperative values DASH Male Female BQ-SS Male Female BQ-F Male Female
41 52 3.3 3.3 2.8 3.0
N: number of patients; SD: standard deviation; CI: confidence interval; DASH: Disabilities of the Arm, Shoulder and Hand questionnaire; BQ-SS: Boston questionnaire symptom severity; BQ-F: Boston questionnaire function.
Table 2—Standardized response means for the DASH, BQ-SS and BQ-F
DASH BQ-SS BQ-F
N
Pre
Post
D
SD
95% CI
P-valuen
SRM
57 57 57
41 3.0 2.6
25 2.0 1.9
15 1.1 0.7
23 1.0 1.1
9, 21 0.8,1.3 0.4,1.0
o0.001 o0.001 o0.001
0.66 1.07 0.62
N: number of patients; Pre: preoperative score; Post: postoperative score; D: mean difference between pre and postoperative values; SD: standard deviation; CI: confidence interval; n P-value of the difference between pre- and postoperative values; SRM: standardized response mean; DASH: Disabilities of the Arm, Shoulder and Hand questionnaire; BQ-SS: Boston questionnaire symptom severity; BQ-F: Boston questionnaire function.
∆ BQ by Age 4 3 2 ∆BQ
∆ - DASH
∆- DASH by Age 70 60 50 40 30 20 10 0 20 -10 -20 -30 -40
30
40
50
60
70
80
90
1 0 20
30
50
60
70
80
90
-2 Age (years)
Age (years) BQ SS BQ F Fig 1
40
-1
Linear (BQ SS) Linear (BQ F)
Change in DASH, BQ-SS and BQ-F scores (from preoperative to 3 months postoperative) compared with age, D: change; DASH: Disabilities of the Arm, Shoulder and Hand questionnaire; BQ-SS: Boston questionnaire symptom severity; BQ-F: Boston questionnaire function.
Practicality Of all the 312 questionnaires completed, a total of 30 (10%) were excluded due to insufficient completion of
the DASH, compared to 2 (1%) for BQ-SS and 17 (5%) for BQ-F (chi-squared statistic, Po0.001) (Fig 3). Of those questionnaires that were adequately completed (i.e. leaving out less than three questions) a mean
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THE JOURNAL OF HAND SURGERY VOL. 29B No. 2 APRIL ∆ - BQ SS by Pre- Op BQ SS
∆ - DASH by Pre - Op DASH
70
3.5
3
60 50 40 30
3
2.5 2
2.5
20 10 0 0 -10
1.5
2
∆- DASH
∆- DASH
∆- DASH
∆- DASH by Pre- Op DASH
1.5 1 0.5
10 20 30 40 50 60 70 80 90 100
0
-20 -30 -40
-0.5
1 0.5 0 -0.5
1
1.5
2
2.5
3
3.5
4
4.5
1
1.5
2
2.5
3
3.5
4
4.5
5
-1
5
-1.5 -2
-1 Pre- Op DASH
Fig 2
2004
Pre - Op BQ SS
Pre - Op BQ F
Change in DASH, BQ-SS and BQ-F scores (from preoperative to 3 months postoperative) compared with preoperative scores. D: change; DASH: Disabilities of the Arm, Shoulder and Hand questionnaire; BQ-SS: Boston questionnaire symptom severity; BQ-F: Boston questionnaire function.
Table 3—Test–retest reliability of DASH, BQ-SS and BQ-F
DASH BQ-SS BQ-F
N
D
SD
31 31 31
1 0.1 0
8 0.4 0.5
95% CI 2, 4 0.1, 0.3 0.2, 0.2
P-value
Reliability coefficient
0.210 0.084 0.564
0.90 0.82 0.79
N: number of patients; D: difference between means (2dp); SD: standard deviation; CI: confidence interval; DASH: Disabilities of the Arm, Shoulder and Hand questionnaire; BQ-SS: Boston questionnaire symptom severity; BQ-F: Boston questionnaire function.
DASH Test Re-Test
80
BQ Symptom Severity Test Re-Test
6
70
BQ Function Test Re-Test 4.5 4 3.5
5 4
40 30
3 Re-Test
50
Re-Test
Re-Test
60 3 2
0
1
1
0.5 0 0
10 20
r = 0.898
Fig 3
2 1.5
20 10
2.5
30
40 50 Test
60
70 80
0
1
2
3
4
5
6
0
0 0.5
Test r = 0.829
1 0.5 2 2.5 3 Test
3.5
4
4.5
r = 0.781
Test–retest reliability plots of the DASH and Boston questionnaires. DASH: Disabilities of the Arm, Shoulder and Hand questionnaire; BQ-SS: Boston questionnaire symptom severity; BQ-F: Boston questionnaire function; r: reliability coefficient.
of 1, 0 and 0 questions were left out for DASH, BQ-SS and BQ-F, respectively. The mean times to complete the questionnaires were 6.8 (SD, 4.8) minutes for the DASH and 5.6 (SD, 3.5) for the BQ. This was a statistically significant difference (Po0.001).
DISCUSSION Outcome measures that evaluate change over time should be reliable, valid and responsive for the specific use for which they are intended (Kirshner and Guyatt,
1985). DASH has been shown to be reliable, valid and responsive in the shoulder (Beaton et al., 2001), elbow (Turchin et al., 1998), wrist and hand (MacDermid et al., 2000). This study provides further support for the responsiveness of the DASH in carpal tunnel syndrome (Gay et al., 2003) and also assesses reliability and practicality. The potential benefits of using just one questionnaire for all upper limb conditions is appealing; however, some authors report that disease-specific scales are more responsive (Wright and Young, 1997). Indeed, the disease-specific BQ is more responsive than many other outcome measures for carpal tunnel syndrome (Amadio et al., 1996; Atroshi et al., 1997; Heybeli et al., 2002;
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DASH AND BOSTON QUESTIONNAIRE ASSESSMENT OF CTS OUTCOME
Mondelli et al., 2000), though it does not take into account social and psychological function. Generic health scales such as the SF-36 are excellent measures of social and psychological function but have the disadvantage of reduced responsiveness (Atroshi et al., 1999; MacDermid et al., 2000). The SF-36 is also less practical for routine clinical use due to the time it takes to complete. Responsiveness can be evaluated in several different ways. Therefore to aid comparison with similar studies we presented our data as a standardized response mean (SRM). SRMs for BQ symptom severity and function (1.07 and 0.62, respectively) are similar to those reported by others (Levine et al., 1993) though Atroshi et al. (1999) had greater improvement at 3 months (1.9 and 1.0). This could be explained by reduced scar pain after arthroscopic decompression which was used in their study. Gay et al. (2003) also report higher SRMs in 34 patients 3 months postoperatively, although the operative technique is not specified. Interestingly the SRMs for the DASH, BQ-SS and BQ-F (1.13, 2.01 and 1.05, respectively) are proportionally very similar. Anecdotally the present authors have noted rapid resolution of paraesthesia and night pain after decompression whilst function is slower to improve, and this may explain the discrepancy between symptom severity and function scores at 3 months. The DASH has 21 questions about physical function and six questions about symptoms, which may explain why its SRM of 0.66 is more comparable to the function part of the BQ. Indeed Gay et al. (2003) also found this association. The significantly higher DASH scores in women preoperatively may be explained by the fact that a higher proportion of women were performing tasks such as making beds and gardening, questions particular to the DASH but not to the BQ. We have found age to correlate negatively with outcome. Interestingly, the BQ-SS has a steeper regression line than the BQ-F (Fig 1) indicating that symptom improvement following carpal tunnel decompression is more sensitive to the negative effects of age than functional improvement. Our data support the findings of Porter et al. (2002) in their prospective study of 87 patients who found less good outcomes in those aged over 60. Tomaino and Weiser (2001) in contrast, found satisfactory outcome in the over 70s, but this was a small retrospective study. We would agree with Porter et al. (2002) that the elderly should be warned that carpal tunnel decompression is only likely to produce modest benefit. Preoperative scores are predictive of outcome in so far as there is a tendency for those with higher scores (worse symptoms and function) to have greater improvement. However this is to be expected, as those with lower preoperative scores have less scope for improvement. This reiterates the point that these outcome instruments should be used for evaluation rather than prediction.
163
Another important finding was the proportion of people who had only marginal improvement or worse scores at 3 months (Figs 4 and 5). The majority of poorer outcomes were due to scar pain, which usually resolves by 6 months after surgery. However, this should remind us of the importance of counselling patients preoperatively about the time needed for some people to achieve an optimal result. Our study adds further support for the reliability of both the BQ and DASH. Test–retest data for BQ-SS and BQ-F gave reliability coefficients of 0.82 and 0.79, respectively. This compares with 0.64 and 0.71 in a similar but smaller sample of 22 patients (Atroshi et al., 1998), 0.87 and 0.85 with Spanish version of the BQ (Rosales et al., 2002), and to 0.91 and 0.93 in Levine et al.’s (1993) original paper. We found that the DASH also had excellent reliability with a coefficient of 0.90, which matches the results of others (Beaton et al., 2001; Rosales et al., 2002; Turchin et al., 1998). The DASH took a mean of 1.2 minutes longer to complete which, although is of statistical significance, is not of clinical relevance. Therefore we feel the DASH is appropriate for use in a busy upper limb clinic. However, as 10% of DASH questionnaires were invalid despite clear verbal and written instructions, further evaluation of the form layout is needed.
Acknowledgements The authors would like to thank Dr R. Elliott, Mrs C. Greenslade and the nursing staff of the Admissions and Short-stay wards for their assistance.
References Amadio P, Silverstein M, Ilstrup D, Schleck C, Jensen L (1996). Outcome assessment for carpal tunnel surgery: The relative responsiveness of generic, arthritis-specific, disease-specific and physical examination measures. Journal of Hand Surgery, 21A: 338–346. Atroshi I, Gummesson C, Johnsson R, Sprinchorn A (1999). Symptoms, disability and quality of life in patients with carpal tunnel syndrome. Journal of Hand Surgery, 24A: 398–404. Atroshi I, Johnsson R, Sprinchorn A (1998). Self-administered outcome instrument in carpal tunnel syndrome. Acta Orthopaedica Scandinavia, 69: 82–88. Atroshi I, Breidenbach WC, McCabe SJ (1997). Assessment of the carpal tunnel outcome instrument in patients with nerve-compression symptoms. Journal of Hand Surgery, 22A: 222–227. Beaton D, Katz J, Fossel A, Wright J, Tarasuk V, Bombardier C (2001). Measuring the whole or the parts? Validity, reliability and responsiveness of the disability of the arm, shoulder and hand outcome measure in different regions of the upper extremity. Journal of Hand Therapy, 14: 128–146. Dubert T, Voche P, Dumontier C, Dihn A (2001). Le questionnaire DASH. Adaption francaise d’un outil d’evaluation international. Chirurgie de la Main, 20: 294–302. Gay R, Amadio P, Johnson J (2003). Comparative responsiveness of the DASH, the carpal tunnel questionnaire and the SF-36 to clinical change after carpal tunnel release. Journal of Hand Surgery, 28A: 250–254. Germann G, Wind G, Harth A (1999). The DASH questionnaire – a new instrument for evaluating upper extremity treatment outcome. Handchir Mikrochir Plast Chir, 31: 149–152. Heybeli N, Kutluhan S, Demirci S, Kerman M, Mumcu EF (2002). Assessment of outcome of carpal tunnel syndrome: a comparison of electrophysiological findings and a self-administered Boston questionnaire. Journal of Hand Surgery, 27B: 259–264.
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164 Hudak P, Amadio P, Bombardier C (1996). Development of an upper extremity outcome measure: the DASH (disabilities of the arm, shoulder and hand). American Journal of Industrial Medicine, 29: 602–608. Katz J, Gelberman R, Wright E, Lew R, Liang M (1994). Responsiveness of selfreported and objective measures of disease severity in carpal tunnel syndrome. Medical Care, 32: 1127–1133. Kirshner B, Guyatt G (1985). A methodological framework for assessing health indices. Journal of Chronic Diseases, 38: 27–36. Levine DW, Simmons BP, Mark JK et al. (1993). A self-administered questionnaire for the assessment of severity of symptoms and functional status in carpal tunnel syndrome. Journal of Bone and Joint Surgery, 75A: 1585–1592. MacDermid JC, Richards RS, Donner A, Bellamy N, Roth J (2000). Responsiveness of the short form-36, disability of the arm, shoulder, and hand questionnaire, patient rated wrist evaluation, and physical impairment measures in evaluating recovery after a distal radius fracture. Journal of Hand Surgery, 25A: 330–340. Mondelli M, Reale F, Sicurelli F, Padua L (2000). Relationship between the selfadministered Boston questionnaire and electrophysiological findings in follow-up of surgically treated carpal tunnel syndrome. Journal of Hand Surgery, 25B: 128–134. Porter P, Venkateswaren B, Stephenson H, Wray CC (2002). The influence of age on outcome after operation for the carpal tunnel syndrome. Journal of Bone and Joint Surgery, 84B: 688–691. Rosales RS, Delgado EB, Diez de la Lastra-Bosch I (2002). Evaluation of the Spanish version of the DASH and carpal tunnel syndrome health-related
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quality-of-life instruments: cross-cultural adaptation process and reliability. Journal of Hand Surgery, 27A: 334–343. SooHoo NF, McDonald AP, Seiler JG, McGillvary GR (2002). Evaluation of the construct validity of the DASH questionnaire by correlation to the SF-36. Journal of Hand Surgery, 27A: 537–541. Tomaino M, Weiser R (2001). Carpal tunnel release for advanced disease in patients 70 years and older: does outcome from the patient’s perspective justify surgery? Journal of Hand Surgery, 26B: 481–483. Turchin DC, Beaton DE, Richards RR (1998). Validity of observer-based aggregate scoring systems as descriptors of elbow pain, function, and disability. Journal of Bone and Joint Surgery, 80A: 154–162. Wright J, Young N (1997). A comparison of different indices of responsiveness. Journal of Clinical Epidemiology, 50: 239–246.
Received: 10 June 2003 Accepted after revision: 20 October 2003 Mr David Warwick, MD, FRCS, FRCS(orth), Consultant Hand Surgeon, Department of Orthopaedics, F-level, Southampton General Hospital, Tremona Road, Southampton SO16 6YD, UK. Tel.: +44-2380-796248; E-mail: [email protected] r 2004 The British Society for Surgery of the Hand. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhsb.2003.10.010 available online at http://www.sciencedirect.com
DASH AND BOSTON QUESTIONNAIRE ASSESSMENT OF CARPAL TUNNEL SYNDROME OUTCOME: WHAT IS THE RESPONSIVENESS OF AN OUTCOME QUESTIONNAIRE? J. R. GREENSLADE, R. L. MEHTA, P. BELWARD and D. J. WARWICK From the Upper Limb Team, Department of Orthopaedics and Research and Development Support Unit, Southampton University Hospital, Southampton, UK
This prospective study evaluates if the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire is an adequately responsive outcome measure in carpal tunnel syndrome by comparing it with the disease-specific Boston questionnaire (BQ). To measure responsiveness (sensitivity to clinical change), 57 patients with a clinical diagnosis of carpal tunnel syndrome completed the DASH and BQ preoperatively and again 3 months after open carpal tunnel decompression. A second group of 31 patients completed the questionnaires in the outpatient clinic and again 2 weeks later to assess test–retest reliability. The time to complete all questionnaires was recorded. Responsiveness of the DASH is comparable with the BQ with standardized response means of 0.66, 1.07 and 0.62 for the DASH, BQ-symptoms and BQ-function, respectively. Test–retest data show both questionnaires are reliable. Mean times to complete questionnaires were 6.8 minutes (DASH) and 5.6 minutes (BQ). This study concludes that the DASH questionnaire is a reliable, responsive and practical outcome instrument in carpal tunnel syndrome. Journal of Hand Surgery (British and European Volume, 2004) 29B: 2: 159–164 Keywords: carpal tunnel release, DASH questionnaire, outcome measures
Katz et al., 1994; Mondelli et al., 2000) and has been validated in other languages (Atroshi et al., 1998; Levine et al., 1993). It comprises two sections, one assessing symptoms such as pain and paraesthesia (BQ symptom severity or BQ-SS), and the second analysing function (BQ-F) in terms of eight day-to-day tasks. A mean score for both symptom severity and functional status is given. The Disability of the Arm, Shoulder and Hand (DASH) questionnaire (Hudak et al., 1996) is designed for use in any upper limb disorder and has been validated in several different languages (Dubert et al., 2001; Germann et al., 1999; Rosales et al., 2002). It has been compared with generic instruments such as the SF-36 (SooHoo et al., 2002), and with outcome measures for the shoulder, elbow, wrist and hand (Beaton et al., 2001; MacDermid et al., 2000; Turchin et al., 1998). It is a 30-item questionnaire with 21 questions concerning function, six symptom severity and three psychosocial factors. Some authors have found disease-specific questionnaires more sensitive to clinical change (Amadio et al., 1996; MacDermid et al., 2000), whilst others have shown the DASH to be comparable to, or better than, joint-specific measures (Beaton et al., 2001). In this study, we aimed to prospectively compare the Boston and DASH questionnaires to measure responsiveness and test–retest reliability. We also aimed to assess their ‘‘practicality’’ for routine use by recording the time taken by the patient to finish each questionnaire and by analysing those incorrectly completed.
INTRODUCTION It is important to assess accurately the outcome of interventions when defining the quality of medical care. Determination of the outcome of carpal tunnel decompression by the operating surgeon is subject to observer bias (Levine et al., 1993) and this bias can be overcome by the use of self-administered questionnaires which address impact on physical function, as well as social and emotional well being. They also have the resource advantage of not requiring input from trained staff during completion. Self-administered questionnaires have superior responsiveness (sensitivity to clinical change) when compared with objective tests in hand surgery such as two-point discrimination, Semmes–Weinstein pressure sensibility, abductor pollicus brevis, grip and pinch strength (Amadio et al., 1996; Atroshi et al., 1999; Katz et al., 1994; MacDermid et al., 2000). Several studies have demonstrated no correlation between ‘‘objective’’ neurophysiological testing and patients’ symptoms following carpal tunnel decompression (Heybeli et al., 2002; Mondelli et al., 2000) and observer-based questionnaires have also been shown to be less responsive than selfadministered questionnaires (Turchin et al., 1998). The Boston questionnaire (BQ) is self-administered (Levine et al., 1993) and is a well-recognized, validated outcome instrument specific for use in carpal tunnel syndrome. It has been compared with many different outcome measures (Amadio et al., 1996; Atroshi et al., 1997–1999; Beaton et al., 2001; Heybeli et al., 2002; 159
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PATIENTS AND METHOD We prospectively followed 88 patients diagnosed with carpal tunnel syndrome at Southampton University Hospitals from March 2002 until September 2002. The study had local Research Ethics Committee approval. Patients were excluded if they had diabetes, thyroid disease, rheumatoid arthritis, gout, radiculopathy of the cervical spine, pregnancy, ipsilateral upper limb pathology requiring surgery or recurrent carpal tunnel syndrome following previous surgery. Decompression was open, by a palmar incision, with a high arm tourniquet. All procedures were performed as a day case under local anaesthetic except for three, which were under general anaesthetic due to patient preference. The procedure was undertaken by several different surgeons of different grade, thus reflecting practice in our unit. Two patient groups were studied. The first was recruited preoperatively on the day of surgery. The DASH and BQ were completed before the operation and a second questionnaire was posted to each patient 3 months after surgery. The second group was recruited to assess reliability. Patients with a diagnosis of carpal tunnel syndrome being listed for decompression answered the questionnaire in the outpatient clinic. Questionnaire completion was repeated 2 weeks later and returned by post. This interval was thought to be long enough to prevent the patient remembering previous answers, but not so long as to allow a significant change in symptom severity. Practicality was compared in both groups by measuring three variables. Firstly, patients recorded completion time of every questionnaire. Secondly, the number of rejected questionnaires due to three or more missed responses was compared. Finally, the total number of missed items for those not rejected (less than three) was noted.
Statistical analysis, methods and techniques The mean preoperative and postoperative scores for DASH, BQ-SS and BQ-F were calculated. For each of these measures the standardized response mean (mean difference between the paired scales divided by the standard deviation of the paired difference, SRM) was calculated. The SRM is a point estimate of the effect measured; 0.2 indicating small, 0.5 indicating moderate and greater than 0.8 large change. A comparison between the preoperative and postoperative scales was performed using analyses of variance techniques and t-tests for continuous data. For categorical data, a chi-squared test was performed. Linear regression analysis was performed to assess the relationship of the percentage change (D) between preoperative and postoperative scales against the independent age. The regression coefficient beta was calculated for age.
THE JOURNAL OF HAND SURGERY VOL. 29B No. 2 APRIL
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In group 2, a correlation of DASH, BQ-SS and BQ-F between the first and fourteenth days was measured using the Pearson’s correlation coefficient. Reliability coefficients were calculated which is a measure of the relative magnitude of association among the series of measures between the two times.
RESULTS One hundred and eighty-eight patients completed forms preoperatively, but 15 were excluded due to confounding variables (ipsilateral trigger finger release, revision surgery) leaving 173 eligible for the study. One hundred were recruited to group 1 and 73 to group 2. One hundred and twenty-four patients (72%) returned forms by post. Twenty-one forms were excluded due to a delay in their return which may have skewed test–retest data due to disease progression. One patient died during the follow-up period and 14 were excluded due to insufficient questions answered, leaving 57 in group 1 and 31 in group 2. Responsiveness (Group 1) Of the 57 patients who completed questionnaires 90 days (range, 85–100) postoperatively, 16 were men and 41 women (Table 1). Their mean age was 57 (range, 49– 65) years and 59 (range, 53–64) years for men and women, respectively. Figure 2 shows that women had significantly higher DASH scores preoperatively (P=0.012), but this pattern was not observed in the BQ. The postoperative scores did not differ significantly between genders (Table 1). The mean improvement in DASH score 3 months postoperatively was 15 (Table 2). The DASH SRM of 0.66 is marginally higher than the BQ-F SRM of 0.62 indicating higher responsiveness. However, the DASH was less responsive than the BQ-SS, which had a SRM of 1.07. Age was found to correlate negatively with outcome for the DASH and BQ (Fig 1). There was a correlation between preoperative scores and change in score, in that the higher the preoperative score the greater the improvement, and vice versa. This pattern was observed for DASH, BQ-SS and BQ-F (Fig 2). Test–retest reliability (Group 2) Thirty-one patients returned second forms by post 14 (range, 10–16) days after the first form. As anticipated, if there was a low score in the initial assessment then there was also a low score in the re-test. This was also observed with high scores. The mean differences bet-ween test and re-test scores for each individual were not significantly different from zero, and the reliability co-efficients were markedly and consistently high (Table 3 and Fig 3).
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Table 1—DASH, BQ-SS and BQ-F scores compared to gender
(a) Preoperative values DASH BQ-SS BQ-F
Gender
N
Mean score
SD
95% CI
Male Female Male Female Male Female
16 41 16 41 16 41
29 45 2.9 3.1 2.3 2.7
22 21 0.8 0.6 0.9 0.9
17, 39, 2.5, 2.9, 1.8, 2.5,
16 41 16 41 16 41
18 28 1.9 2.0 1.7 2.0
23 25 0.9 1.0 1.0 1.0
6,31 20, 36 1.4, 2.4 1.7, 2.3 1.1, 2.2 1.7, 2.4
(b) Three month postoperative values DASH Male Female BQ-SS Male Female BQ-F Male Female
41 52 3.3 3.3 2.8 3.0
N: number of patients; SD: standard deviation; CI: confidence interval; DASH: Disabilities of the Arm, Shoulder and Hand questionnaire; BQ-SS: Boston questionnaire symptom severity; BQ-F: Boston questionnaire function.
Table 2—Standardized response means for the DASH, BQ-SS and BQ-F
DASH BQ-SS BQ-F
N
Pre
Post
D
SD
95% CI
P-valuen
SRM
57 57 57
41 3.0 2.6
25 2.0 1.9
15 1.1 0.7
23 1.0 1.1
9, 21 0.8,1.3 0.4,1.0
o0.001 o0.001 o0.001
0.66 1.07 0.62
N: number of patients; Pre: preoperative score; Post: postoperative score; D: mean difference between pre and postoperative values; SD: standard deviation; CI: confidence interval; n P-value of the difference between pre- and postoperative values; SRM: standardized response mean; DASH: Disabilities of the Arm, Shoulder and Hand questionnaire; BQ-SS: Boston questionnaire symptom severity; BQ-F: Boston questionnaire function.
∆ BQ by Age 4 3 2 ∆BQ
∆ - DASH
∆- DASH by Age 70 60 50 40 30 20 10 0 20 -10 -20 -30 -40
30
40
50
60
70
80
90
1 0 20
30
50
60
70
80
90
-2 Age (years)
Age (years) BQ SS BQ F Fig 1
40
-1
Linear (BQ SS) Linear (BQ F)
Change in DASH, BQ-SS and BQ-F scores (from preoperative to 3 months postoperative) compared with age, D: change; DASH: Disabilities of the Arm, Shoulder and Hand questionnaire; BQ-SS: Boston questionnaire symptom severity; BQ-F: Boston questionnaire function.
Practicality Of all the 312 questionnaires completed, a total of 30 (10%) were excluded due to insufficient completion of
the DASH, compared to 2 (1%) for BQ-SS and 17 (5%) for BQ-F (chi-squared statistic, Po0.001) (Fig 3). Of those questionnaires that were adequately completed (i.e. leaving out less than three questions) a mean
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THE JOURNAL OF HAND SURGERY VOL. 29B No. 2 APRIL ∆ - BQ SS by Pre- Op BQ SS
∆ - DASH by Pre - Op DASH
70
3.5
3
60 50 40 30
3
2.5 2
2.5
20 10 0 0 -10
1.5
2
∆- DASH
∆- DASH
∆- DASH
∆- DASH by Pre- Op DASH
1.5 1 0.5
10 20 30 40 50 60 70 80 90 100
0
-20 -30 -40
-0.5
1 0.5 0 -0.5
1
1.5
2
2.5
3
3.5
4
4.5
1
1.5
2
2.5
3
3.5
4
4.5
5
-1
5
-1.5 -2
-1 Pre- Op DASH
Fig 2
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Pre - Op BQ SS
Pre - Op BQ F
Change in DASH, BQ-SS and BQ-F scores (from preoperative to 3 months postoperative) compared with preoperative scores. D: change; DASH: Disabilities of the Arm, Shoulder and Hand questionnaire; BQ-SS: Boston questionnaire symptom severity; BQ-F: Boston questionnaire function.
Table 3—Test–retest reliability of DASH, BQ-SS and BQ-F
DASH BQ-SS BQ-F
N
D
SD
31 31 31
1 0.1 0
8 0.4 0.5
95% CI 2, 4 0.1, 0.3 0.2, 0.2
P-value
Reliability coefficient
0.210 0.084 0.564
0.90 0.82 0.79
N: number of patients; D: difference between means (2dp); SD: standard deviation; CI: confidence interval; DASH: Disabilities of the Arm, Shoulder and Hand questionnaire; BQ-SS: Boston questionnaire symptom severity; BQ-F: Boston questionnaire function.
DASH Test Re-Test
80
BQ Symptom Severity Test Re-Test
6
70
BQ Function Test Re-Test 4.5 4 3.5
5 4
40 30
3 Re-Test
50
Re-Test
Re-Test
60 3 2
0
1
1
0.5 0 0
10 20
r = 0.898
Fig 3
2 1.5
20 10
2.5
30
40 50 Test
60
70 80
0
1
2
3
4
5
6
0
0 0.5
Test r = 0.829
1 0.5 2 2.5 3 Test
3.5
4
4.5
r = 0.781
Test–retest reliability plots of the DASH and Boston questionnaires. DASH: Disabilities of the Arm, Shoulder and Hand questionnaire; BQ-SS: Boston questionnaire symptom severity; BQ-F: Boston questionnaire function; r: reliability coefficient.
of 1, 0 and 0 questions were left out for DASH, BQ-SS and BQ-F, respectively. The mean times to complete the questionnaires were 6.8 (SD, 4.8) minutes for the DASH and 5.6 (SD, 3.5) for the BQ. This was a statistically significant difference (Po0.001).
DISCUSSION Outcome measures that evaluate change over time should be reliable, valid and responsive for the specific use for which they are intended (Kirshner and Guyatt,
1985). DASH has been shown to be reliable, valid and responsive in the shoulder (Beaton et al., 2001), elbow (Turchin et al., 1998), wrist and hand (MacDermid et al., 2000). This study provides further support for the responsiveness of the DASH in carpal tunnel syndrome (Gay et al., 2003) and also assesses reliability and practicality. The potential benefits of using just one questionnaire for all upper limb conditions is appealing; however, some authors report that disease-specific scales are more responsive (Wright and Young, 1997). Indeed, the disease-specific BQ is more responsive than many other outcome measures for carpal tunnel syndrome (Amadio et al., 1996; Atroshi et al., 1997; Heybeli et al., 2002;
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Mondelli et al., 2000), though it does not take into account social and psychological function. Generic health scales such as the SF-36 are excellent measures of social and psychological function but have the disadvantage of reduced responsiveness (Atroshi et al., 1999; MacDermid et al., 2000). The SF-36 is also less practical for routine clinical use due to the time it takes to complete. Responsiveness can be evaluated in several different ways. Therefore to aid comparison with similar studies we presented our data as a standardized response mean (SRM). SRMs for BQ symptom severity and function (1.07 and 0.62, respectively) are similar to those reported by others (Levine et al., 1993) though Atroshi et al. (1999) had greater improvement at 3 months (1.9 and 1.0). This could be explained by reduced scar pain after arthroscopic decompression which was used in their study. Gay et al. (2003) also report higher SRMs in 34 patients 3 months postoperatively, although the operative technique is not specified. Interestingly the SRMs for the DASH, BQ-SS and BQ-F (1.13, 2.01 and 1.05, respectively) are proportionally very similar. Anecdotally the present authors have noted rapid resolution of paraesthesia and night pain after decompression whilst function is slower to improve, and this may explain the discrepancy between symptom severity and function scores at 3 months. The DASH has 21 questions about physical function and six questions about symptoms, which may explain why its SRM of 0.66 is more comparable to the function part of the BQ. Indeed Gay et al. (2003) also found this association. The significantly higher DASH scores in women preoperatively may be explained by the fact that a higher proportion of women were performing tasks such as making beds and gardening, questions particular to the DASH but not to the BQ. We have found age to correlate negatively with outcome. Interestingly, the BQ-SS has a steeper regression line than the BQ-F (Fig 1) indicating that symptom improvement following carpal tunnel decompression is more sensitive to the negative effects of age than functional improvement. Our data support the findings of Porter et al. (2002) in their prospective study of 87 patients who found less good outcomes in those aged over 60. Tomaino and Weiser (2001) in contrast, found satisfactory outcome in the over 70s, but this was a small retrospective study. We would agree with Porter et al. (2002) that the elderly should be warned that carpal tunnel decompression is only likely to produce modest benefit. Preoperative scores are predictive of outcome in so far as there is a tendency for those with higher scores (worse symptoms and function) to have greater improvement. However this is to be expected, as those with lower preoperative scores have less scope for improvement. This reiterates the point that these outcome instruments should be used for evaluation rather than prediction.
163
Another important finding was the proportion of people who had only marginal improvement or worse scores at 3 months (Figs 4 and 5). The majority of poorer outcomes were due to scar pain, which usually resolves by 6 months after surgery. However, this should remind us of the importance of counselling patients preoperatively about the time needed for some people to achieve an optimal result. Our study adds further support for the reliability of both the BQ and DASH. Test–retest data for BQ-SS and BQ-F gave reliability coefficients of 0.82 and 0.79, respectively. This compares with 0.64 and 0.71 in a similar but smaller sample of 22 patients (Atroshi et al., 1998), 0.87 and 0.85 with Spanish version of the BQ (Rosales et al., 2002), and to 0.91 and 0.93 in Levine et al.’s (1993) original paper. We found that the DASH also had excellent reliability with a coefficient of 0.90, which matches the results of others (Beaton et al., 2001; Rosales et al., 2002; Turchin et al., 1998). The DASH took a mean of 1.2 minutes longer to complete which, although is of statistical significance, is not of clinical relevance. Therefore we feel the DASH is appropriate for use in a busy upper limb clinic. However, as 10% of DASH questionnaires were invalid despite clear verbal and written instructions, further evaluation of the form layout is needed.
Acknowledgements The authors would like to thank Dr R. Elliott, Mrs C. Greenslade and the nursing staff of the Admissions and Short-stay wards for their assistance.
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Received: 10 June 2003 Accepted after revision: 20 October 2003 Mr David Warwick, MD, FRCS, FRCS(orth), Consultant Hand Surgeon, Department of Orthopaedics, F-level, Southampton General Hospital, Tremona Road, Southampton SO16 6YD, UK. Tel.: +44-2380-796248; E-mail: [email protected] r 2004 The British Society for Surgery of the Hand. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhsb.2003.10.010 available online at http://www.sciencedirect.com