Direct and indirect costs associated with nonoperative treatment for shoulder instability: an observational study in 132 patients.

BACKGROUND: Shoulder instability is associated with decreased functioning. The associated costs could be substantial and interesting to clinicians, researchers, and policy makers. This prospective observational study aims to (1) estimate productivity losses and healthcare expenses following the nonoperative treatment of shoulder instability and (2) identify patient characteristics that influence societal costs. METHODS: One hundred and thirty-two patients completed a questionnaire regarding production losses and healthcare utilization following consecutive episodes of shoulder instability. Productivity losses were calculated using the friction cost approach. Healthcare utilization was evaluated using standard costs. analysis of variance test was used to assess which patient characteristics are related to productivity losses and healthcare expenses. Societal costs were assessed using multilevel analyses. Bootstrapping was used to estimate statistical uncertainty. RESULTS: Mean productivity losses are €1469, €881, and €728 and mean healthcare expenses are €3759, €3267, and €2424 per patient per dislocation for the first, second, and third dislocation. Productivity losses decrease significantly after the second (mean difference €-1969, 95%CI= -3680 to -939) and third (mean difference €-2298, 95%CI= -4092 to -1288) compared to the first dislocation. CONCLUSIONS: Nonoperative treatment of shoulder instability has substantial societal costs. LEVEL OF EVIDENCE: III, economic analysis.

The Responsiveness and Minimal Important Change of the Western Ontario Shoulder Instability Index and Oxford Shoulder Instability Score.

Study Design Prospective cohort study. Background Patient-reported outcome measurements (PROMs) are widely used to evaluate functional limitations. Considering PROMs for shoulder instability, information is lacking with regard to what constitutes a relevant change from baseline scores. Objectives To evaluate the responsiveness of the Western Ontario Shoulder Instability Index (WOSI) and the Oxford Shoulder Instability Score (OSIS) and estimate their minimal important change (MIC). Methods One hundred five consecutive patients with shoulder instability completed 5 PROMs at baseline and at 6-month follow-up. The PROMs included the WOSI and OSIS, the Simple Shoulder Test, the Oxford Shoulder Score, and the Disabilities of the Arm, Shoulder and Hand assessment. Patients also rated their functional change on an anchor question at follow-up. Responsiveness was evaluated by testing 9 hypotheses regarding predefined correlations between the changes in PROM scores, by calculating the area under the receiver operating characteristic curve and by calculating the standardized response mean and effect size statistics. The MIC was determined by identifying the optimal cutoff on the receiver operating characteristic curve. Results Seven out of 9 hypotheses (78%) were confirmed; as expected, a high correlation (0.77) was found between change scores of the WOSI and OSIS, whereas the correlations of the change scores of the WOSI and OSIS with those of general shoulder PROMs were slightly lower (0.61-0.75). The area under the curve was 0.83 (95% confidence interval: 0.75, 0.91) for the OSIS and 0.82 (95% confidence interval: 0.74, 0.90) for the WOSI. The MIC was about 6 points for the OSIS and about 14 points for the WOSI. Conclusion Both the WOSI and OSIS are able to measure change in shoulder function in patients with shoulder instability. The estimated MIC is 6 points for the OSIS (on a scale from 0 to 48) and 14 points for the WOSI (on a scale from 0 to 100). J Orthop Sports Phys Ther 2017;47(6):402-410. doi:10.2519/jospt.2017.6548.

The Oxford Shoulder Instability Score; validation in Dutch and first-time assessment of its smallest detectable change.

BACKGROUND: The Oxford Shoulder Instability Score (OSIS) is a short, self-reported outcome measurement for patients with shoulder instability. In this study, the OSIS was validated in Dutch by testing the internal consistency, reliability, measurement error, validity and the floor and ceiling effects, and its smallest detectable change (SDC) was calculated. METHODS: A total of 138 patients were included. Internal consistency was calculated with Cronbach's α. Reliability (test-retest) was calculated with the intraclass correlation coefficient (ICC). The measurement error was calculated (SEM), and the SDC was estimated in a subgroup of 99 patients that completed the re-test after a mean of 13 days (5-30 days). Construct validity was evaluated by comparing the OSIS with the Western Ontario Shoulder Instability index (WOSI), the Simple Shoulder Test (SST), the Oxford Shoulder Score (OSS), the Disability of the Arm, Shoulder, and Hand assessment (DASH), and the Short Form-36 (SF-36). RESULTS: Internal consistency was good, with a Cronbach's α of 0.88. The reliability was excellent, with an ICC of 0.87. The SEM was 3.3 and the SDC was 9 points (on a scale of 0-48). Regarding the construct validity, 80% of the results were in accordance with the hypotheses, including a high correlation (0.82) with the WOSI. No floor or ceiling effects were found. CONCLUSIONS: The Dutch version of the OSIS showed good reliability and validity in a cohort of patients with shoulder instability.