Diagnostic properties of nerve conduction tests in population-based carpal tunnel syndrome

BACKGROUND: Numerous nerve conduction tests are used for the electrodiagnosis of carpal tunnel syndrome (CTS), with a wide range of sensitivity and specificity reported for each test in clinical studies. The tests have not been assessed in population-based studies. Such information would be important when using electrodiagnosis in epidemiologic research. The purpose of this study was to compare the diagnostic accuracy of various nerve conduction tests in population-based CTS and determine the properties of the most accurate test. METHODS: In a population-based study a questionnaire was mailed to a random sample of 3,000 persons. Of 2,466 responders, 262 symptomatic (numbness/tingling in the radial fingers) and 125 randomly selected asymptomatic responders underwent clinical and electrophysiologic examinations. A standardized hand diagram was administered to the symptomatic persons. At the clinical examination, the examining surgeon identified 94 symptomatic persons as having clinically certain CTS. Nerve conduction tests were then performed on the symptomatic and the asymptomatic persons by blinded examiners. Analysis with receiver operating characteristic (ROC) curves was used to compare the diagnostic accuracy of the nerve conduction tests in distinguishing the persons with clinically certain CTS from the asymptomatic persons. RESULTS: No difference was shown in the diagnostic accuracy of median nerve distal motor latency, digit-wrist sensory latency, wrist-palm sensory conduction velocity, and wrist-palm/forearm sensory conduction velocity ratio (area under curve, 0.75–0.76). Median-ulnar digit-wrist sensory latency difference had a significantly higher diagnostic accuracy (area under curve, 0.80). Using the optimal cutoff value of 0.8 ms for abnormal sensory latency difference shown on the ROC curve the sensitivity was 70%, specificity 82%, positive predictive value 19% and negative predictive value 98%. Based on the clinical diagnosis among the symptomatic persons, the hand diagram (classified as classic/probable or possible/unlikely CTS) had high sensitivity but poor specificity. CONCLUSIONS: Using the clinical diagnosis of CTS as the criterion standard, nerve conduction tests had moderate sensitivity and specificity and a low positive predictive value in population-based CTS. Measurement of median-ulnar sensory latency difference had the highest diagnostic accuracy. The performance of nerve conduction tests in population-based CTS does not necessarily apply to their performance in clinical settings

Performance of health-status scales when used selectively or within multi-scale questionnaire

BACKGROUND: Little work has been done to investigate the suggestion that the use of selected scales from a multi-scale health-status questionnaire would compromise reliability and validity. The aim of this study was to compare the performance of three scales selected from the SF-36 generic health questionnaire when administered in isolation or within the entire SF-36 to patients with musculoskeletal disorders. METHODS: Two groups of patients referred to an orthopedic department completed a mailed questionnaire within 4 weeks prior to and a second questionnaire during their visit. The first group completed three SF-36 scales related to physical health (physical functioning, bodily pain, and general health perceptions) on one occasion and all eight SF-36 scales on the other occasion. The second group completed the entire SF-36 on two occasions. Results for patients who reported unchanged health status and had complete scores were analyzed; 80 patients in the first and 62 patients in the second group. RESULTS: The Cronbach alpha reliability and intraclass correlation coefficients exceeded 0.7 for all three scales for both groups. For the first group the mean difference between the scores was 0.4 point for physical functioning, 2.5 points for bodily pain, and 0.5 point for general health perceptions, which did not differ significantly from the corresponding differences for the second group (0.1, 1.9 and 1 point, respectively). CONCLUSION: The use of selected scales from a multi-scale health-status questionnaire seems to yield similar results compared to their use within the entire questionnaire

The disabilities of the arm, shoulder and hand (DASH) outcome questionnaire: longitudinal construct validity and measuring self-rated health change after surgery

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

The transition of reported pain in different body regions – a one-year follow-up study

BACKGROUND: The course of pain at a specific region such as the lower back has previously been shown as well as for generalized pain. However we have not found any report on the course of pain from various different specific regions. The aim of this investigation was to study the one-year transition of reported pain in different body locations. METHODS: From a general population 14555 men and women, 46–68 years, responded to an extensive health questionnaire including the standardized Nordic questionnaire. The population represented 27% of the total population within the age group in Malmö, Sweden. At the one year follow-up 12607 responded to the questionnaire, yielding a response rate of 87%. The one year prevalence of long-lasting pain and the pattern of pain reporting from different regions were studied for men and women. RESULTS: The one-year prevalence of long-lasting neck pain was 14% (95% CI 13–15) among men and 25% (95% CI 24–26) among women at baseline and 15% (95% CI 14–16) for the men and 23% (95% CI 22–24) for the women at follow-up. Of those reporting neck pain "all the time" at baseline, 48% of the men and 54% of the women also reported neck pain "all the time" at the one-year follow-up. At the follow-up neck pain was reported as present "often" by 43% of the men and 47% of the women who reported neck pain "often" at baseline. Similar transition pattern were found for neck, shoulders, elbow/wrist/hand and lower back symptoms, as well as consistent prevalence rates. CONCLUSION: The one-year transition pattern of reported pain was similar in different body regions and among men and women. Furthermore the prevalence rates of long-lasting pain in the population were consistent at baseline and the follow-up. The findings of similar transition patterns support the interpretation of long-lasting pain as a generalized phenomenon rather than attributed to specific exposure. This may have implications for future pain research

Upper Extremity Disorders - Epidemiology and Measures of Disability

The aim of this thesis was to investigate the prevalence and characteristics of long-lasting upper extremity symptoms in a general population and to study some methodological aspects of outcome assessment and reporting, including validation of a Swedish version of an upper extremity region-specific outcome instrument that potentially could be useful for assessing upper extremity disorders. A general health questionnaire was mailed to 3000 persons, randomly selected from a general population register; response rate 83%. The prevalence of long-lasting (> 6 months) upper extremity pain associated with activity limitations was estimated to 20.8%, and that of co-occurring long-lasting numbness/tingling was 6.7%. Of the participants 84% reported pain at more than one location. The second study aimed to introduce a Swedish version of the Disabilities of the Arm, Shoulder and Hand(DASH) outcome instrument and evaluate its reliability and validity. Following the process of translation and cultural adaptation the Swedish version of the DASH was found to be a reliable and valid instrument that can provide a standardized measure of patient-centered outcomes in upper extremity musculoskeletal conditions. In the third study, the quality of reporting and the outcome measures used in randomized clinical trials related to treatment of upper extremity disorders published in four orthopedic and hand surgical journals during 1992-2002 were assessed. Of the 92 articles assessed, only 40 (43%) described a randomization method that was judged to be appropriate indicating they were truly randomized. The outcome measures used were mainly on body function/structure level. The fourth study aimed to assess the longitudinal construct validity of the DASH. The DASH could 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. When a region-specific outcome instrument is used, combination with a generic instrument may be needed in the outcome assessment. Using an entire multi-scale generic instrument including scales that may not be relevant to the study purpose results in a lengthy questionnaire, increasing responder burden. Although selected scales have been commonly used, the reliability and validity of selective use of scales have not been studied. The aim of the fifth study was to assess the performance of health-status scales when used selectively or within multi-scale questionnaire. The use of selected scales about physical health from a multi-scale health-status questionnaire seemed to yield similar results compared to their use within the entire questionnaire