Tinnitus handicap inventory for evaluating treatment effects: which changes are clinically relevant?

Area of Science:

• Audiology
• Clinical Psychology
• Health Outcomes Research

Background:

• The Tinnitus Handicap Inventory (THI) is a widely used patient-reported outcome measure for tinnitus severity.
• Establishing a minimal clinically relevant difference (MCRD) for the THI is crucial for interpreting study results and guiding clinical practice.

Purpose of the Study:

• To determine the minimal change in Tinnitus Handicap Inventory (THI) scores that signifies a clinically relevant improvement for tinnitus patients.
• To compare THI score changes with the Clinical Global Impression–Improvement (CGI-I) scale.

Main Methods:

• Utilized data from 210 patients in the Tinnitus Research Initiative (TRI) database.
• Employed equipercentile linking to compare THI score changes with CGI-I ratings.
• Categorized CGI-I into four groups and calculated THI score differences and effect sizes to identify the MCRD.

Main Results:

• Equipercentile linking indicated a THI score reduction of 6–16 points for 'minimally better' (CGI-I=3).
• An effect size of d = 0.5 was determined to differentiate between 'no change' and 'minimally better' groups.
• This resulted in a minimal clinically relevant difference of a 7-point reduction in the THI score (ΔTHI = 7).

Conclusions:

• Two distinct methodologies converged, identifying a 6- to 7-point reduction in THI scores as the minimal clinically relevant change.
• These findings offer essential guidance for future tinnitus research, particularly in sample size determination and study design.