Clinically relevant differences in COPD health status: Systematic review and triangulation

Background: The Minimal Clinically Important Difference (MCID) quantifies when measured differences can be considered clinically relevant. This study aims to review and triangulate MCIDs of COPD health status tools.Methods: A systematic search in PubMed, EMBASE and Cochrane Library was conducted (Prospero #CRD42015023221). Study details, patient characteristics, MCID methodology and estimates were assessed and extracted by two authors. MCIDs were triangulated by weighing: 2/3 anchor-based and 1/3 distribution-based results, the size and quality rating of the included studies.Results: Overall, 785 records were reviewed of which 21 studies were included for analysis. MCIDs of 12 tools were presented. General quality and risk of bias was average to good. Triangulated MCIDs for CAT, CCQ, and SGRQ were -2.54, -0.43 and -7.43 for improvement. Too few and/or too diverse studies were present to triangulate MCIDs of other tools.Conclusions: Evidence for the MCID of the CAT and CCQ was strong and triangulation seemed valid. Currently used MCIDs in clinical practice for SGRQ (4) and CRQ (0.5) did not match the reviewed content, which turned out much higher. Using too low MCIDs may lead to overestimation of the interpretation of treatment effects. MCIDs for deterioration were scarce and highlights need for more research.