Validation of the minimal clinically important difference for modified activities assessment scale

Abstract

BackgroundThe minimal clinically important difference (MCID) is the smallest change in patient-derived scores that is clinically important. We sought to validate the MCID of the modified activities assessment scale (mAAS). MethodsPatients were surveyed prior to undergoing abdomen/pelvis CT scans and resurveyed one year later. Before resurvey, patients were asked if they had no change, worsening, or improvement in AW-QOL. The anchor-based MCID was calculated by taking a weighted mean of the difference between control (no change) and study (worsening/improved) groups. Distribution-based approach was calculated by one-half of the standard deviation in the QOL change. Results52.8% of 181 patients self-reported no change, 39.2% reported improvement, and 8.3% reported worsening AW-QOL. The anchor-based approach MCID was 4. The distribution-based MCID was 16. ConclusionOur study results validate prior work demonstrating similar ranges of the mAAS MCID. We recommend adopting an MCID of 5 and 15 for AW-QOL with mAAS.