Language: English French

A DASH score may notbe calculated if there are greater than 3 missing items. DASH DISABILITY/SYMPTOM SCORE = (sum of n responses ( / n) - 1 x 25, where n is the number of completed responses. D ISABILITIES OF THE A RM, S HOULDER AND H AND.

Abstract

The aim of this study was to critically analyse the various outcome measures available for assessing wrist and hand function. To this end, an extensive literature search was performed on Medline, PubMed and the Science Citation Index, focusing on terms associated with the method of development of the outcome measures item generation, item reduction, validity, reliability, internal consistency and their strengths and weaknesses. The most commonly used outcome measures described in literature were the DASH score (disability of shoulder, arm and hand questionnaire), the PRWE score (patient-rated wrist evaluation questionnaire), the Brigham and Women's carpal tunnel questionnaire and the Gartland and Werley score. Our study provides very useful evidence to suggest that the PRWE score is the most responsive instrument for evaluating the outcome in patients with distal radius fractures, while the DASH score is the best instrument for evaluating patients with disorders involving multiple joints of the upper limb. The Brigham and Women's score is a disease-specific outcome instrument for carpal tunnel syndrome; it has been validated and demonstrated to show good responsiveness and reliability in evaluating outcome in patients with carpal tunnel release. The Gartland and Werley score, although the most commonly described instrument in the literature for evaluating outcome after wrist surgery, has not been validated so to date.

Résumé

Le but de ce travail est d’analyser de façon critique les différents scores fonctions du poignet et de la main. Une analyse importante de la littérature a été réalisée sur Medline, PubMed et l’Index Science Citation. Cette analyse a été complète prenant en compte les différents scores. La méthode de mesure la plus habituelle a été le score DASH pour les lésions de l’ épaule, du bras et de la main, le score PRWE (pour le poignet), celui de Brigham pour le canal carpien et surtout le poignet, le score de Gartland et celui de Werley. Notre étude permet de mettre en évidence que le score le plus adapté pour les fractures de l’extrémité distale du radius est le score PRWE. Le score DASH est le meilleur instrument pour mesurer les atteintes multiples des articulations des membres supérieurs. Le score de Brigham est spécialement adapté au syndrome du canal carpien, le score de Gartland et Werley est le score le plus habituellement utilisé dans la littérature pour évaluer la chirurgie du poignet.

Introduction

Outcome assessment has become important in evaluating the efficacy of surgical procedures. In accordance with this, most orthopaedic surgeons are now of the opinion that a proper outcome assessment should be performed after any form of surgery. Such an assessment facilitates surgeons in distinguishing between various treatment methods and helps to identify effective treatment options which, in turn, improves patient care.

A wide variety of outcome measures have been proposed for upper limb extremity disorders, including those for the evaluation of wrist and hand function. Some of these are generic instruments, such as the Short Form (SF)-36 [] and sickness impact profile []. These generic measures assess the impact of musculoskeletal problems on the overall health and well being of patients, and they were designed for broad use in a variety of disorders. However, more specific outcome instruments have been designed for specific use in musculoskeletal problems, including those specific for anatomical regions, such as the patient-rated wrist evaluation score (PRWE) [], and those for outcome measures for specific diseases, such as carpal tunnel syndrome (CTS) [].

The traditional methods for evaluating wrist and hand function following an intervention consist of measuring grip strength and assessing the range on motion, both which provide a good, objective analysis of outcome. However, these methods do not take into account other aspects related to an analysis of outcome, such as the patient’s ability to carry out activities of daily living, the ability to return to previous occupations and pain. Hudak et al. [] emphasised that to evaluate outcome following hand surgery, appropriate, reliable and validated outcome measures are required that take into account all aspects of patient life that may be affected.

This aim of this article is to critically analyse the outcome measures commonly used in the evaluation of wrist and hand function.

Materials and methods

An extensive literature search was carried out on Medline, PubMed and other search engines available online. The outcome instruments described in the literature for evaluating wrist and hand function are the disability of shoulder, arm and hand questionnaire (DASH), Brigham and Women’s Hospital carpal tunnel questionnaire (CTQ), the patient-rated wrist evaluation questionnaire (PRWE), the Gartland and Werley score, the hospital for special surgery wrist scoring system (HSS), the Lamberta and Clayton wrist score and the Wrightington wrist function score. We selected the four most commonly used instruments – the DASH questionnaire, PRWE score, Gartland and Werley score and Brigham and Women's Hospital CTQ – for further evaluation in terms of their development, validity, reliability, consistency and strengths and weaknesses.

Analysis of outcome measures

DASH questionnaire

The DASH score was first described in 1996 by Hudak et al. []. The main objective behind its development was to develop a regional outcome measure which conceptualises the upper extremity as a single functional unit. This would allow greater uniformity in research and would give greater relevance to the input from the patient himself rather than relying on other factors, such as radiographs, range of motion and grip strength.

DASH claims to assess both symptoms and functional status with a focus on physical function in populations with upper extremity musculoskeletal conditions. DASH is self administered by patients and aims to capture the patient’s own perception of upper extremity function.

Development, item generation and item reduction

Thirteen scales and 821 items were chosen after extensive review of the literature, and these were used in measuring the outcomes of various upper extremity conditions. The initial item reduction was done on the basis of judgement from experts, with a subsequent reduction to 177 items. These were later reduced to 75 by content experts and finally reduced to 30 items after preliminary testing on patients.

Scoring

The DASH questionnaire comprises 30 items that evaluate symptoms and physical function with five response options for each item. The final score can be calculated using a simple formula:

The questionnaire takes the patient 10–15 min to complete and the administrator takes another 10 min to calculate the final score, which makes this a time-consuming outcome instrument. The reliability, as reported by Cronbach’s alpha, is 0.9615, and test–retest reliability is 0.9219.

Construct validity

Convergent construct validity was demonstrated through the correlation between the DASH score and other joint specific instruments, such as the Brigham CTQ (0.73) and SPADI (shoulder pain and disability index) (0.72). The correlation of DASH with severity of pain in the wrist joint was weak (0.67), making it less valid for use in patients with wrist disorders.

Test–retest reliability

A group of 86 patients was asked to complete DASH at baseline and then 3–5 days later. The Pearson correlation between the baseline and retest scores was 0.96, suggesting an excellent reproducibility for the DASH score.

Responsiveness

The change in DASH was found to correlate well with changes in the patient's condition. The DASH questionnaire demonstrated a change in all situations in which change presumably occurred. The standardised response mean (SRM) of 0.74 for DASH was comparable to 0.76 for such joint specific outcome measures as the Brigham score. This demonstrates the ability of DASH to differ in accordance with alterations in the patient’s condition and its ability to show even very small change.

Brigham and Women’s Hospital CTQ

This self-administered questionnaire was first described by Levine et al. in 1993 []. It was developed to assess the severity of symptoms and functional status and response to treatment in patients with CTS.

Development, item generation and reduction

Following consultation with hand surgeons and rheumatologists, Levine et al. identified six critical domains for the evaluation of CTS: pain, test–retest reliability of paraesthesia, numbness, weakness, nocturnal symptoms and overall functional status []. A symptom severity scale was developed comprising 11 questions incorporating these six domains. Twelve functional activities commonly affected in CTS, such as writing and holding a cup, were also identified. These were reduced to eight after pilot testing and included in the questionnaire as a functional status scale.

Scoring

The patients were asked to answer all 11 questions included in the symptom severity scale and the eight questions included in the functional status scale. The answer to each multiple-choice question ranged from mild (1 point ) to most severe (5 points). The overall score was calculated as the sum of the mean of scores for all items on the symptom severity scale and functional status scale.

Validity

Content validity was tested by consulting a group of hand surgeons, rheumatologists and patients. A correlation between the scores on the scales and a variety of physical instruments, such as grip strength and pinch strength, used for measuring hand function was determined through a prospective study on 67 patients. The scores for severity of symptoms had a moderate Spearman correlation with grip and pinch strength. The functional status scores had a high correlation with the severity of the symptoms and a moderate correlation with grip and pinch strength. A correlation was also calculated for patient satisfaction after the operation and the improvement in scores: a greater satisfaction was associated with a greater improvement in scores for both the severity of symptoms and functional status. All of these correlations were statistically significant. Overall, this indicated a good validity for the CTQ score.

Test–retest reliability

A group of 39 patients were asked to complete the questionnaire on two separate occasions on two consecutive days. The Pearson correlation coefficient was 0.91 for the symptom severity scale and 0.93 for functional status, indicating very good reproducibility.

Internal consistency

Cronbach’s alpha indicating inter-item correlation within each scale was 0.89 for the symptom severity scale and 0.91 for the functional status scale. This implies an excellent internal consistency between the different items on the scale and also means that the scales could function well as a unidimensional index of severity of symptoms and functional status for patients with CTS.

Responsiveness

Responsiveness was tested on 38 patients who underwent carpal tunnel release surgery. The preoperative symptom severity score was 3.4 ± 0.67 (mean and SD); the mean postoperative score was 1.9 ± 1.0. These scores indicate a substantial responsiveness to clinical change. The effect size was 1.4. The preoperative functional status score was 3.0 ± 0.93 compared with the postoperative functional score of 2.0 ± 1.1, again a substantial improvement. The effect size in this case was 0.82. As an additional indicator of responsiveness, the correlation between patient satisfaction with the results of the operation and the reduction in score was calculated. This correlation was good, suggesting that CTQ is sensitive to change in the clinical picture in patients with CTS.

Patient-rated wrist evaluation score

The PRWE score was originally described by MacDermid et al. in 1998 []. The aim of the questionnaire is to provide a reliable and valid tool for quantifying patient-rated wrist pain and disability in order to assess outcome in patients with distal radius fractures.

Development, item generation and reduction

The questionnaire was developed by surveying wrist experts, reviewing the biomechanical literature and carrying out patient interviews. This resulted in the identification of the domains of pain and function as priorities for the evaluation of wrist function. The items in both these essential domains were further reduced by expert and patient review as well as pilot testing. Pain items were modified to incorporate the whole spectrum of severity, both in intensity and frequency. Functional items were modified to include items that were commonly performed by either hand, performed by most of the patients and easy to understand. The intention was that the questionnaire be simple and brief.

Scoring

It is self administered by the patient. The score consists of two domains – pain and function – both of which carry equal weight. There are five items in the pain domain and ten items in the function domain. The response to each item is scored on a scale of 0–10. The pain score is the sum of five items, a worse score of 50; the disability (function) score is the sum of ten items, divided by 2. Thus, the total function on the PRWE scale ranges from 0 (normal wrist) to 150 (worst possible score).

Construct validity

The change in the disability over time was evaluated in 101 patients with wrist fractures. A statistically significant improvement was found (p < 0.0001), with the amount of improvement being 74% as compared to the SF-36 score, which reported an improvement of 14% (p < 0.0001).

Criterion validity

The PRWE score was correlated with the SF-36 score and with an impairment score that was based on an assessment of physical functions, such as range of movement of wrist joint, grip strength and dexterity. The PRWE score showed a correlation with the SF-36 score of between 0.33 and 0.73. There was a low correlation with the SF-36 mental summary score and a high correlation with bodily pain score and physical function score. The PRWE score correlated poorly – 0.52 (weak to moderate correlation) – with an impairment score (score for the measurement of function impairment in patients, which raises questions over the validity of this score, as an impairment score is the aspect which corresponds to the function of the PRWE scale, an important aspect when evaluating outcome in patients with distal radius fractures.

Test–retest reliability

This was tested on three groups of patients. Groups 1 and 2 comprised patients with distal radius fractures currently undergoing physiotherapy and having completed physiotherapy, respectively, while Group 3 patients had scaphoid fracture non-union and were tested for long-term retest reliability. A short-term retest reliability testing was performed on the first two groups. An excellent intra-class correlation (ICC; >0.90) was found for pain subscales for all three groups. The function subscales showed an excellent reliability in the distal radius fracture group (ICC > 0.85) but only moderate reliability over the long-term in Group 3 (ICC > 0.61). No appropriate testing for internal consistency and responsiveness was performed, which makes the PRWE score rather weak in terms of overall reliability.

Gartland and Werley score

This is one of the most commonly used outcome measures for evaluating wrist and hand function. This was initially described in 1951 by Gartland and Werley []. This score is completed by the administrator after the patient has been examined.

This system is based on a demerit point system which involves an objective evaluation of wrist function. It relies on the concept that a minimum of 45° dorsiflexion, 30° palmar flexion, 15° ulnar and radial deviation and 50° pronation and supination is normal. Demerit points are given based on the presence of a specific arbitrarily determined degree of loss of range of movement. For example, five points are given for a 45° loss of dorsiflexion, and only one point is given for loss of palmar flexion of more than 30°. Depending on the number of points scored, the outcome is classified as excellent, good or poor. Sarmiento et al. [] later modified the system to include a loss of pronation and grip strength.

Lucas and Sachtjen [] further modified it by adding such non-objective variables of hand as median nerve impairment, reflex sympathetic dystrophy and the stiffness of digits. They removed grip strength from the criteria of functional outcome. These changes were implemented to incorporate all of the possible outcomes and complications that can occur following wrist injuries, particularly distal radius fractures.

Validity, reliability and responsiveness

Despite the extensive use of this outcome measure, there have been no validity studies carried out to date. This is the one of the very few outcome measures which we found to provide an objective evaluation of outcome and may well be the reason that makes this measure very popular among orthopaedic surgeons. However, no appropriate methodology seems to have been applied for identifying the domains which makes this less reliable for use.

Discussion

The relatively large number of outcome measures available for evaluating wrist and hand function provides clinicians with a wide range of choice, thereby enabling them to use that outcome instrument which is the most appropriate and suitable. The choice of an outcome measure is determined by the clinical condition one wishes to assess; the resources available and the psychometric properties are often additional determining factors [].

We analysed the DASH score because this is the only score which considers the whole upper limb as a single unit; as such, it may be useful for assessing outcome in any upper limb pathology irrespective of the site []. PRWE was analysed as this score is specific for the outcome from one joint. The Brigham CTQ was chosen for analysis as it is disease-specific. The Gartland and Werley score is the most commonly used outcome measure in the literature and the only one dependent on the administrator’s objective assessment.

Karnezis et al. [] compared the association between objective clinical variables, such as grip strength and wrist movements, and PRWE score by means of regression analysis, which revealed the limitations of objective assessment in reflecting the level of disability of the wrist. These researchers were unable to establish an association between PRWE and the Gartland and Werley score, which proved that movements of the wrist joint and grip strength alone are not a reliable way of measuring outcome. Gay and et al. [] analysed the comparative responsiveness of the DASH score, the Brigham wrist score and the SF-36 to clinical change after carpal tunnel release. The instrument most sensitive to clinical change, assessed at 12 weeks post-carpal tunnel release, was the Brigham score (effect size/standardised response means; 1.71/1.66), followed by the DASH score (1.01/1.13) and the SF-36 score (0.57/0.52). There was a good correlation between the DASH and the Brigham score (Spearman correlation coefficient: 0.87), which makes the Brigham score a reliable, valid and sensitive tool for assessing outcome in patients with CTS.

Beaton et al. [] compared the validity, reliability and responsiveness of the DASH score with those obtained from joint-specific measures and found that the former correlated well with other joint-specific measures such as the Brigham and Women's CTQ score for the wrist joint and the SPADI score for the shoulder joint. They also found that the responsiveness of the DASH score to self-rated or expected change was comparable to or better than other joint-specific measures, both in the whole group and in each region. This confirmed the usefulness of the DASH score across the whole upper limb, particularly in patients with multiple upper limb joint involvement.

Macdermid et al. [] compared the responsiveness of the DASH, PRWE and SF-36 scores in evaluating recovery after distal radius fractures. The PRWE score was the most responsive of the three in this particular group of patients (SRM: 2.27), followed by the DASH (SRM: 2.01) and the SF-36 (SRM: 0.92). This makes the PRWE score a reasonably reliable, valid and sensitive tool for assessing outcome in patients with distal radius fractures.

Conclusion

Table ​Table11 presents a summary of the four outcome instruments discussed in detail in this article. The DASH score is the best instrument for evaluating patients with disorders involving multiple upper limb joints. The Brigham score is a disease-specific validated outcome instrument for carpal tunnel syndrome. The PRWE score is a validated tool for assessing outcome in patients with distal radius fractures, and the Gartland and Werley score provides an objective assessment of outcome, but its use has not yet been validated.

Table 1

^aDASH, Disability of shoulder, arm and hand questionnaire; CTQ, the Brigham and Women's Hospital carpal tunnel questionnaire; PRWE, patient-rated wrist evaluation questionnaire

References

Abstract

Background

The disabilities of the arm, shoulder and hand (DASH) questionnaire is a self-administered region-specific outcome instrument developed as a measure of self-rated upper-extremity disability and symptoms. The DASH consists mainly of a 30-item disability/symptom scale, scored 0 (no disability) to 100. The main purpose of this study was to assess the longitudinal construct validity of the DASH among patients undergoing surgery. The second purpose was to quantify self-rated treatment effectiveness after surgery.

Methods

The longitudinal construct validity of the DASH was evaluated in 109 patients having surgical treatment for a variety of upper-extremity conditions, by assessing preoperative-to-postoperative (6–21 months) change in DASH score and calculating the effect size and standardized response mean. The magnitude of score change was also analyzed in relation to patients' responses to an item regarding self-perceived change in the status of the arm after surgery. Performance of the DASH as a measure of treatment effectiveness was assessed after surgery for subacromial impingement and carpal tunnel syndrome by calculating the effect size and standardized response mean.

Results

Among the 109 patients, the mean (SD) DASH score preoperatively was 35 (22) and postoperatively 24 (23) and the mean score change was 15 (13). The effect size was 0.7 and the standardized response mean 1.2.

The mean change (95% confidence interval) in DASH score for the patients reporting the status of the arm as 'much better' or 'much worse' after surgery was 19 (15–23) and for those reporting it as 'somewhat better' or 'somewhat worse' was 10 (7–14) (p = 0.01). In measuring effectiveness of arthroscopic acromioplasty the effect size was 0.9 and standardized response mean 0.5; for carpal tunnel surgery the effect size was 0.7 and standardized response mean 1.0.

Conclusion

The DASH can detect and differentiate small and large changes of disability over time after surgery in patients with upper-extremity musculoskeletal disorders. A 10-point difference in mean DASH score may be considered as a minimal important change. The DASH can show treatment effectiveness after surgery for subacromial impingement and carpal tunnel syndrome. The effect size and standardized response mean may yield substantially differing results.

Background

The disability of the arm, shoulder and hand (DASH) questionnaire is an upper-extremity specific outcome measure that was introduced by the American Academy of Orthopedic Surgeons in collaboration with a number of other organizations[]. The rationale behind the use of one outcome measure for different upper extremity disorders is that the upper extremity is a functional unit[]. In this respect, the DASH would be suitable because of its property of being mainly a measure of disability. In addition to decreasing the administrative burden associated with using different disease-specific measures, one of the main concepts behind developing the DASH was to facilitate comparisons among different upper-extremity conditions in terms of health burden[]. The DASH is now available in several languages http://www.dash.iwh.on.ca, and studies of reliability and validity have been published for the original version[] as well as for the German[], Italian[], Spanish[] and Swedish[] versions. In addition, research studies regarding a French[] and a Dutch[] version of the DASH have been published.

The DASH is being increasingly used in cross-sectional studies. To enhance the use of the DASH in prospective studies (such as assessment of effectiveness of different treatment methods) further studies of the instrument's ability to detect change over time would be helpful both for interpretation of score changes and for sample size calculations. Different aspects of an instrument's ability to measure change have been highlighted including studying changes over time for groups or individuals and comparing groups at one occasion[]. The analysis of score change is commonly referred to as responsiveness[-], but the term longitudinal construct validity has also been used[] and it has been advocated that responsiveness is a part of the validity analysis[]. There is no consensus on the nomenclature or the appropriate statistical analysis and different suggestions have been made[,-]. To facilitate prospective research, longitudinal studies of the instrument's ability to detect changes and identify smaller and larger changes in health status as perceived by the patient are needed.

We believe that the concept of detecting change over time is part of the validity assessment and therefor may be referred to as longitudinal construct validity. To date, we have found only one published study concerning the longitudinal construct validity of the DASH in a variety of orthopedic disorders of the upper extremity[]. Considering the nature of the instrument, longitudinal construct validity can be assessed among a group of patients with different upper extremity disorders. In contrast, when using the instrument in patients with a particular diagnosis the effectiveness of a specific treatment can be assessed. To analyze treatment effectiveness the direction of change becomes important, as opposed to analyzing longitudinal construct validity, which concerns the ability to detect change irrespective of whether the change is improvement or worsening. Therefor it would be important to study the longitudinal construct validity of the DASH as well as its performance as a measure of treatment effectiveness.

The main purpose of this study was to assess the longitudinal construct validity of the DASH among patients undergoing surgery for a variety of upper extremity disorders. The second purpose was to quantify self-rated treatment effectiveness after surgery for subacromial impingement and carpal tunnel syndrome when using the DASH. To ensure reliability of the DASH in this study we also aimed to determine the internal consistency of the scale in each patient population studied.

Methods

The DASH questionnaire

The main part of the DASH is a 30-item disability/symptom scale concerning the patient's health status during the preceding week[20]. The items ask about the degree of difficulty in performing different physical activities because of the arm, shoulder, or hand problem (21 items), the severity of each of the symptoms of pain, activity-related pain, tingling, weakness and stiffness (5 items), as well as the problem's impact on social activities, work, sleep, and self-image (4 items). Each item has five response options. The scores for all items are then used to calculate a scale score ranging from 0 (no disability) to 100 (most severe disability). The score for the disability/symptom scale is called the DASH score. In this study we used the Swedish version of the DASH[].

Patients

Patients with upper-extremity musculoskeletal conditions planned for surgical treatment at an orthopedic department were considered for inclusion in this study. Exclusion criteria were age below 18 years, symptom duration of less than 2 months, or inability to complete questionnaires due to cognitive impairment or language difficulties. The DASH was completed preoperatively by 118 consecutive eligible patients[]. Postoperatively, 9 (8%) of the patients did not respond and the remaining 109 patients completed the DASH after a minimum followup time of 6 months (Table ​(Table1).1). The 2 largest diagnostic groups comprised patients who had undergone arthroscopic acromioplasty because of subacromial impingement and open carpal tunnel release because of carpal tunnel syndrome. Complete followup could be obtained for all patients in these 2 subgroups (Table ​(Table22).

Table 1

Characteristics of all the responders and the two largest subgroups who completed the DASH before and after surgery, and the patients who did not respond after surgery (dropouts)

Table 2

The followup questionnaire also included an item regarding change in health status after surgery. It inquired about the status of the operated arm compared to its status preoperatively (5 response options: much better, somewhat better, unchanged, somewhat worse, much worse). This item was accidentally missing in the initially mailed questionnaires and was therefore only completed by the last 83 participants.

Analyses

To assess one aspect of the reliability of the DASH scale when used in this patient population, the internal consistency was calculated using Cronbach alpha[21] for the total population as well as for the subgroups with subacromial impingement and carpal tunnel syndrome. For each of these populations, preoperative, postoperative and change scores were computed for the DASH. These scores were subjected to the one-sample Kolmogorov-Smirnov test to assess normality of distribution. As a measure of longitudinal construct validity, the effect size and standardized response mean were calculated for the DASH disability/symptom scale. The effect size was calculated as the mean difference between the baseline scores and the followup scores (i.e., mean change scores) divided by the standard deviation of the baseline scores. The standardized response mean was calculated as the mean change scores divided by the standard deviation of the change scores.

As external criterion for change in health status after surgery the item regarding how the patient rated the status of the operated arm compared to its status preoperatively was used. Because detecting both improvement and worsening reflect longitudinal construct validity, the preoperative-to-postoperative score differences were considered to be in the same direction and the mean change in DASH score and the 95% confidence interval (CI) was calculated for the patients with the responses of 'much better' or 'much worse' and those with the responses 'somewhat better' or 'somewhat worse'. The difference in the mean change scores between these two groups was assessed with the t-test.

For patients who reported that no change had occurred, the mean change in DASH score and the 95% CI were calculated (scores used in their actual direction).

The mean change in DASH score for the patients who did not and those who did receive the transition item regarding change in the status of the operated arm was compared with the t-test.

To assess the size of health change after surgery for subacromial impingement and carpal tunnel syndrome (i.e., treatment effectiveness), the change scores were used in their actual direction and the effect size and standardized response mean were calculated.

The relationship between the DASH change score and time since surgery (months) was analyzed with the Pearson correlation coefficient (r).

Results

Reliability

The Cronbach alpha coefficient was above 0.9 for the DASH disability/symptoms scale indicating good internal consistency when used in this patient population (Table ​(Table33).

Table 3

Sonic forces pc download. Internal consistency of the disabilities of the arm, shoulder and hand (DASH) questionnaire measured with the Cronbach alpha coefficient

Longitudinal construct validity

Among the 109 participants the mean (SD) change in DASH score was 15 (13) when all changes in scores (improvement or worsening) were calculated as having the same direction. The effect size was 0.7 and standardized response mean 1.2 (Table ​(Table44).

Table 4

Results of the disabilities of the arm, shoulder and hand (DASH) disability/symptoms scale shown as scores, effect size (ES) and standardized response mean (SRM)

*Higher score (0–100) indicates greater disability ^†All changes in scores (improvement or worsening) calculated as having the same direction (to assess longitudinal validity of the DASH as opposed to assessing treatment effectiveness)

Of the 83 patients who answered the transition item concerning self-rated change in disability and symptoms after surgery the mean change (95% CI) in DASH score in the 53 patients responding 'much better' or 'much worse' was 19 (15–23) and in the 21 patients responding 'somewhat better' or 'somewhat worse' was 10 (7–14), (p = 0.01). For the 9 patients reporting no change in the status of the arm after surgery (clinically stable group) the mean change (95% CI) in DASH score was -0.3 (-3.6–3.0).

The mean change (95% CI) in DASH score for the patients who did not receive the transition item was 16 (11–20) and it was 15 (12–18) for the patients who responded to the item (p = 0.9).

Comparison of measures of treatment effectiveness

For the group with subacromial impingement treated with arthroscopic acromioplasty, the effect size was 0.9 and the standardized response mean 0.5 (Table ​(Table4).4). For the group with carpal tunnel syndrome treated with open carpal tunnel release, the effect size was 0.7 and the standardized response mean 1.0.

Correlation between score change and time since surgery

Among all 109 patients, no correlation was found between the DASH change score and time since surgery (r = 0.06, p = 0.56). The correlation was weak-to-moderate but statistically non-significant among the patients treated with arthroscopic acromioplasty (r = 0.29, p = 0.15) and those treated with carpal tunnel release (r = 0.34, p = 0.16).

Discussion

The importance of monitoring the effectiveness of treatment is well recognized and furthermore is the foundation of evidence-based health care. For this purpose instruments that have the ability to detect changes and can differentiate a small difference from a large difference are needed. In a previous study, the DASH score change was reported for 172 patients with different upper extremity disorders (such as shoulder arthritis and carpal tunnel syndrome). The mean change between baseline and followup scores 12 weeks after treatment was 13 (SD 17), the effect size was 0.6 and the standardized response mean was 0.8[]. The changes were also shown for patients rating their problem as better (mean score change 17, effect size 0.75, standardized response mean 1.1) and patients rating their function as better (mean score change 20, effect size 0.8, standardized response mean 1.2). Also, based on the results of the present study, it appears that the DASH has the ability to detect changes on group level corresponding to the patients' perception after surgery in a variety of upper extremity disorders. A significant difference in DASH scores between patients responding 'much better/worse' and 'somewhat better/worse' was found showing the instruments ability to discriminate between these degrees of change. A mean score change of 19 indicated a change in disability rated as 'much better/worse' and a mean score change of 10 as 'somewhat better/worse'. It has been suggested that the score change rated as 'somewhat changed' could be defined as the limit for minimal important change[]. This information could then be used for power calculations when planning prospective studies. In a recent study a DASH score change of 15 has been suggested to discriminate between improved and unimproved patients[]. This was based on the patients' responses to a question about 'being able to cope with the problem and do what you would like to do', with a response change from 'not being able to cope' before treatment to 'being able to cope' at followup considered as criterion for improvement[]. However, we believe that a change in disability can be important even if the patients are not able to do all what they want to do or, at a particular time, not being able to cope with the problem. Future investigations are needed to determine whether the DASH is sensitive to milder degrees of impact other than that of surgery.

The difference noted in the group stating no change (mean score change -0.3) can be seen as the difference that occurred by chance and was similar to the score change previously reported[,]. A difference of this size should not be considered as a real change of upper extremity disability.

In the analysis of health transition only the last 83 patients were included because the item was accidentally missing in the initially mailed questionnaires. The mean change in DASH score did not significantly differ between the patients who did not receive and those who responded to the transition item suggesting that it is unlikely the missing item could have substantially influenced the results.

We chose to use self-rated change of health status in the operated arm as external criterion in order to ensure that it did not capture global health changes not related to the upper extremities.

Be fast, be first and be famous as the race returns in GRID 2, the sequel to the BAFTA-award winning, multi-million selling Race Driver: GRID. Experience aggressive racing against advanced AI and become immersed in the race with GRID 2’s new TrueFeel™ Handling system which powers edge of control exhilaration behind the wheel of every iconic car. Grid 2 Reloaded Edition for Mac Overview: Be quick, be first and be well-known because the race returns in GRID, the sequel to the BAFTA-award successful, multi-million promoting Race Driver: GRID for Mac. Expertise aggressive racing in opposition to superior AI and turn into immersed within the race with GRID new TrueFeel™ Dealing with. Grid 2 Reloaded MacOSX Cracked Game. – System Requirements: MINIMUM: Other Requirements: The following graphics cards are not supported: ATI X1xxx series, ATI HD2xxx series, Intel GMA series, Intel HD3000, NVIDIA 7xxx series, NVIDIA 8xxx series, NVIDIA 9xxx series, NVIDIA 3xx series and NVIDIA 1xx series. Grid 2 reloaded edition mac torrent. Be fast, be first and be famous as the race returns in GRID 2, the sequel to the BAFTA-award winning, multi-million selling Race Driver: GRID. Experience aggressive racing against advanced AI and become immersed in the race with GRID 2’s new TrueFeel™ Handling system which powers edge of control exhilaration behind the wheel of every iconic.

The minimum followup time in the present study was 6 months and the latest response was received 21 months after surgery. The minimum followup time was chosen as it was expected to be sufficient to show improvement after surgery in most disorders. As shown in the correlation analysis time since surgery had, within this followup period, only weak-to-moderate but statistically non-significant association with the change in DASH scores after arthroscopic acromioplasty and carpal tunnel release. However, the difference in followup time is a limitation that can have implication, particularly when interpreting the size of change in DASH score for the assessment of treatment effectiveness. The possible implication of response shift also needs to be evaluated in future studies.

In this study the DASH demonstrated high Cronbach alpha values, indicating an excellent internal consistency that is adequate for group as well as for individual comparisons[22]. These results support the use of the DASH to measure changes in upper extremity function also on an individual level. However, for individual patient assessment with the DASH the magnitude of score change has to be studied on individual level[]. It is important to note that in the present study only longitudinal construct validity on group level has been analyzed.

The treatment effectiveness calculations showed that for arthroscopic acromioplasty the effect size was larger than the standardized response mean, while for carpal tunnel release the opposite was shown. This illustrates the difficulties with interpretation of such calculations when only one of the analyses is presented. Since the effect size is dependent on the homogeneity of the group preoperatively and the standardized response mean is dependent on the homogeneity of the change of disability, these calculations will by nature differ in almost any group. Both calculation methods are common; however, little has been discussed about the limitations associated with these analyses, though it has been highlighted[,]. The use of the DASH in other populations of similar diagnostic groups and interventions is needed to show the degree of consistency in the estimates of treatment effectiveness.

Conclusions

The DASH can detect and differentiate small and large changes in disability over time after surgery in patients with upper extremity musculoskeletal disorders. A 10-point difference in mean DASH score might be considered as a minimal important change. The DASH can show self-rated treatment effectiveness after surgery for carpal tunnel syndrome and subacromial impingement. The effect size and standardized response mean (commonly used indices of the magnitude of health change measured by questionnaires) may yield substantially differing results.

Authors' contributions

CG and IA participated in the design of the study, data collection and analysis, and writing of this manuscript. CE participated in the analysis and writing of this manuscript. All authors read and approved the final manuscript.

Pre-publication history

The pre-publication history for this paper can be accessed here:

Acknowledgments

This study was supported by the Swedish Foundation for Health Care Sciences and Allergy Research (Vårdal Stiftelse), the Kristianstad County Council and the Skåne County Council.

We thank Gunilla B. Persson and Iréne Nordén for assistance with data collection, Ragnar Johnsson, MD, PhD, for his helpful comments, Gert-Uno Larsson, for his contribution, and Ewald Ornstein for his support. We acknowledge the work of the American Academy of Orthopedic Surgeons and the Institute for Work & Health, Toronto, Canada, in developing the DASH.

References

• Hudak PL, Amadio PC, Bombardier C, The Upper Extremity Collaborative Group (UECG) Development of an upper extremity outcome measure: the DASH (disabilities of the arm, shoulder and hand) [corrected] Am J Ind Med. 1996;29:602–608. doi: 10.1002/(SICI)1097-0274(199606)29:6<602::AID-AJIM4>3.0.CO;2-L. [PubMed] [CrossRef] [3.0.CO;2-L&' target='pmc_ext' ref='reftype=other&article-id=165599&issue-id=4611&journal-id=46&FROM=Article%7CCitationRef&TO=Content%20Provider%7CLink%7CGoogle%20Scholar'>Google Scholar]
• Davis AM, Beaton DE, Hudak P, Amadio P, Bombardier C, Cole D, Hawker G, Katz JN, Makela M, Marx RG, Punnett L, Wright JG. Measuring disability of the upper extremity: a rationale supporting the use of a regional outcome measure. J Hand Ther. 1999;12:269–274. [PubMed] [Google Scholar]
• Beaton DE, Katz JN, Fossel AH, Wright JG, Tarasuk V, Bombardier C. Measuring the whole or the parts? Validity, reliability, and responsiveness of the Disabilities of the Arm, Shoulder and Hand outcome measure in different regions of the upper extremity. J Hand Ther. 2001;14:128–146. [PubMed] [Google Scholar]
• Offenbaecher M, Ewert T, Sangha O, Stucki G. Validation of a German version of the disabilities of arm, shoulder, and hand questionnaire (DASH-G) J Rheumatol. 2002;29:401–402. [PubMed] [Google Scholar]
• Padua R, Padua L, Ceccarelli E, Romanini E, Zanoli G, Amadio PC, Campi A. Italian version of the disability of the arm, shoulder and hand (DASH) questionnaire. Cross-cultural adaptation and validation. J Hand Surg Br. 2003;28:179–186. doi: 10.1016/S0266-7681(02)00303-0. [PubMed] [CrossRef] [Google Scholar]
• Rosales RS, Delgado EB, De La Lastra-Bosch ID. Evaluation of the Spanish version of the DASH and carpal tunnel syndrome health-related quality-of-life instruments: Cross-cultural adaptation process and reliability. J Hand Surg Am. 2002;27:334–343. doi: 10.1053/jhsu.2002.30059. [PubMed] [CrossRef] [Google Scholar]
• Atroshi I, Gummesson C, Andersson B, Dahlgren E, Johansson A. The disabilities of the arm, shoulder and hand (DASH) outcome questionnaire: reliability and validity of the Swedish version evaluated in 176 patients. Acta Orthop Scand. 2000;71:613–618. doi: 10.1080/000164700317362262. [PubMed] [CrossRef] [Google Scholar]
• Dubert T, Voche P, Dumontier C, Dinh A. [The DASH questionnaire. French translation of a trans-cultural adaptation] Chir Main. 2001;20:294–302. doi: 10.1016/S1297-3203(01)00049-X. [PubMed] [CrossRef] [Google Scholar]
• Veehof MM, Sleegers EJ, van Veldhoven NH, Schuurman AH, van Meeteren NL. Psychometric qualities of the Dutch language version of the Disabilities of the Arm, Shoulder, and Hand questionnaire (DASH-DLV) J Hand Ther. 2002;15:347–354. [PubMed] [Google Scholar]
• Beaton DE, Bombardier C, Katz JN, Wright JG, Wells G, Boers M, Strand V, Shea B. Looking for important change/differences in studies of responsiveness. OMERACT MCID Working Group. Outcome Measures in Rheumatology. Minimal Clinically Important Difference. J Rheumatol. 2001;28:400–405. [PubMed] [Google Scholar]
• Deyo RA, Diehr P, Patrick DL. Reproducibility and responsiveness of health status measures: statistics and strategies for evaluation. Control Clin Trials. 1991;12:142S–158S. [PubMed] [Google Scholar]
• Guyatt G, Walter S, Norman G. Measuring change over time: assessing the usefulness of evaluative instruments. J Chronic Dis. 1987;40:171–178. [PubMed] [Google Scholar]
• Ware JEJ, Kemp JP, Buchner DA, Singer AE, Nolop KB, Goss TF. The responsiveness of disease-specific and generic health measures to changes in the severity of asthma among adults. Qual Life Res. 1998;7:235–244. doi: 10.1023/A:1008878031176. [PubMed] [CrossRef] [Google Scholar]
• Wright JG, Young NL. A comparison of different indices of responsiveness. J Clin Epidemiol. 1997;50:239–246. doi: 10.1016/S0895-4356(96)00373-3. [PubMed] [CrossRef] [Google Scholar]
• Stratford PW, Binkley FM, Riddle DL. Health status measures: strategies and analytic methods for assessing change scores. Phys Ther. 1996;76:1109–1123. [PubMed] [Google Scholar]
• Liang MH. Longitudinal construct validity: establishment of clinical meaning in patient evaluative instruments. Med Care. 2000;38:II84–II90. doi: 10.1097/00005650-200009002-00013. [PubMed] [CrossRef] [Google Scholar]
• Beaton DE, Boers M, Wells GA. Many faces of the minimal clinically important difference (MCID): a literature review and directions for future research. Curr Opin Rheumatol. 2002;14:109–114. doi: 10.1097/00002281-200203000-00006. [PubMed] [CrossRef] [Google Scholar]
• Husted JA, Cook RJ, Farewell VT, Gladman DD. Methods for assessing responsiveness: a critical review and recommendations. J Clin Epidemiol. 2000;53:459–468. doi: 10.1016/S0895-4356(99)00206-1. [PubMed] [CrossRef] [Google Scholar]
• Liang MH, Lew RA, Stucki G, Fortin PR, Daltroy L. Measuring clinically important changes with patient-oriented questionnaires. Med Care. 2002;40:II45–II51. [PubMed] [Google Scholar]
• Solway S, Beaton DE, McConnell S, Bombardier C. Toronto, Ontario: Institute for Work & Health. 2nd. 2002. The DASH Outcome Measure User's Manual; p. 5. [Google Scholar]
• Streiner DL, Norman GR. Oxford: Oxford University Press. 2nd. 1995. Health measurement scales: A practical guide to their development and use; p. 64. [Google Scholar]
• Nunnally JC, Bernstein IH. New York: McGraw-Hill. 3rd. 1994. Psychometric theory; p. 265. [Google Scholar]