A concise shoulder outcome measure: application of computerized adaptive testing to the American Shoulder and Elbow Surgeons Shoulder Assessment

Abstract

Patient-reported outcome measures enable quantitative and patient-centric assessment of orthopedic interventions; however, increased use of these forms has an associated burden for patients and practices. We examined the utility of a computerized adaptive testing (CAT) method to reduce the number of questions on the American Shoulder and Elbow Surgeons (ASES) instrument. A previously developed ASES CAT system was applied to the responses of 2763 patients who underwent shoulder evaluation and treatment and had answered all questions on the full ASES instrument. Analyses to assess the accuracy of the CAT score in replicating the full-form score included the mean and standard deviation of both groups of scores, frequency distributions of the 2 sets of scores and score differences, Pearsonand intraclass correlation coefficients, and Bland-Altman assessment of patterns in score differences. By tailoring questions according to prior responses, CAT reduced the question burden by 40%. The mean difference between CAT and full ASES scores was -0.14, and the scores were within 5 points in 95% of cases (a 12-point difference is considered the threshold for clinical significance) and were clustered around zero. The correlation coefficients were 0.99, and the frequency distributions of the CAT and full ASES scores were nearly identical. The differences between scores were independent of the overall score, and no significant bias for CAT scores was found in either a positive or negative direction. The ASES CAT system lessens respondent burden with a negligible effect on score integrity.