Estimation of Minimal Clinically Important Difference for Tinnitus Handicap Inventory and Tinnitus Functional Index.

Abstract

The minimal clinically important difference (MCID) represents the smallest change in treatment outcome deemed clinically meaningful. This study estimates the MCID for 2 widely used tinnitus measures: the Tinnitus Handicap Inventory (THI) and the Tinnitus Functional Index (TFI), using anchor-based approaches while accounting for baseline severity and time interval. A multi-center randomized clinical trial. European tinnitus centers. Anchor-based approaches, including the effect size, receiver-operating characteristics, and ΔTHI/TFI methods, were employed to determine the MCID. The "minimally improved" category of the Clinical Global Impression Scale-Improvement (CGI-I) served as the anchor. The standard error of measurement was used to assess random variation. For the THI, MCID estimates ranged from 7.8 to 12, with a point estimate of 11 after 12 weeks of treatment (N = 364). For the TFI, MCID estimates ranged from 7.3 to 9.4, with a point estimate of 9 points after 12 weeks (N = 359). Both measures indicated that higher baseline severity and longer time intervals required greater score reduction for clinical relevance. This study highlights the context-specific nature of MCID values for tinnitus measures and emphasizes the need for consensus on optimal anchor-based approaches to improve comparability.