Summary
Of the three short form versions of the KOOS that are currently available the KOOS-Global had the greatest responsiveness to change between 2- and 5-years post ACL reconstruction surgery.
Abstract
Background
Various short form versions of the Knee injury and Osteoarthritis Outcome Score (KOOS) have been developed in an attempt to minimize responder burden. However, the responsiveness of these short form measures in patients who have undergone anterior cruciate ligament (ACL) reconstruction has not been determined at a mid-term follow-up.
Purpose
To determine the responsiveness of three short form versions of the KOOS (KOOS-12, KOOS-Global and KOOS-ACL) in patients who have undergone ACL reconstruction.
Study Design: Cohort
Methods
The KOOS and a measure of overall knee function were administered at both 2- and 5-years following ACL reconstruction surgery. From the full KOOS the following short form versions were calculated: KOOS-12 Short form, KOOS-Global and KOOS-ACL. Responsiveness was assessed using several distribution and anchor-based methods for each of the short form versions. From distribution statistics the standardized response mean (SRM) and smallest detectable change (SDC) score were calculated. Using the anchor-based method, the minimally important change (MIC) score that was associated with an improvement in knee function was determined using receiver operating characteristic (ROC) analysis.
Results
276 (149M, 127F) patients participated. High ceiling effects were present for all measures. Only KOOS-Global scores significantly increased over time, whereas KOOS-12 and KOOS-ACL did not change. The quality of life (QOL) subscale, which can be derived from both KOOS-Global and KOOS-12 also significantly increased between assessments. Both these increases were associated with a small (0.2-0.3) SRM. The MIC score was smallest at 3.2 points for KOOS-Global and largest at 9.4 points for KOOS-QOL, and for all measures MIC scores were larger than the SDC score at a group level. KOOS-Global was the only measure for which the mean difference between the two assessments exceeded both the SDC (group level) and MIC.
Conclusion
Of the three short form versions of the KOOS that are currently available the KOOS-Global had the greatest responsiveness to change between 2- and 5-years post ACL reconstruction surgery.