Responsiveness of five outcome measurement instruments in total elbow arthroplasty

Abstract

To quantify and compare the sensitivity to change of 5 outcome instruments for the elbow joint. In a prospective cohort study (n = 65), outcome was measured by the Short Form 36 (SF-36), the Disabilities of the Arm, Shoulder, and Hand questionnaire (DASH), the modified American Shoulder and Elbow Surgeons questionnaire for the elbow, patient part (pmASES) and examiner/clinical part (cmASES), and the Patient-Rated Elbow Evaluation form (PREE). Responsiveness was quantified by the effect size (ES) and standardized response mean (SRM) before and 6 months after total elbow arthroplasty. Receiver operating characteristic (ROC) curves were used to determine the instruments' ability to classify effects into global health change assessment categories. For the total scores, the ES were 1.50 for the PREE, 1.32 for the pmASES, 0.86 for the cmASES, 0.56 for the DASH, and 0.11 for the SF-36 (P ≤ 0.002 for all differences, except the cmASES and DASH). The same order was found within the subdomains of pain/symptoms and function and remained consistent when using the SRM and in ROC curve analysis. PREE total (area under the ROC curve 0.68), DASH function, and pmASES total and pain (area under the ROC curve range 0.64-0.67) discriminated best between "much better" and the other categories. The PREE was the most responsive instrument and can be recommended for every set of measures for elbow joint disorders. The pmASES was slightly less responsive but is a valid alternative. The examiner-assessed cmASES is affected by concerns regarding validity and was relatively less responsive. The DASH for comprehensive measurement of the entire upper extremity and the SF-36 for chronic pain conditions complete the assessment set.