Background:Patient-reported outcomes (PROs) capture patients’ perspectives on treatment benefits and harms. Understanding PROs requires determining a level of improvement or deterioration that patients consider important. The most common reference point for interpretation of PROs is the minimal important difference (MID), which provides a measure of the smallest change in a PRO that patients perceive as an important benefit or harm. No inventory of MIDs is currently available. Thus, clinicians and patients have to navigate the vast literature in order to retrieve a specific MID. Even if they find an MID, there is no guidance to help them ascertain the trustworthiness of the apparently applicable MID.
Objectives:To create an inventory of published anchor-based MIDs associated with PROs used in evaluating the effects of interventions on chronic medical and psychiatric conditions in adults, including the context in which they were assessed (condition/disease), and the confidence users can place in a particular MID.
Methods:We searched MEDLINE, EMBASE, PsycINFO and CINAHL to identify studies addressing methods to estimate anchor-based MIDs of PROs or reporting empirical ascertainment of anchor-based MIDs. Teams of two reviewers independently screened citations, and identified and extracted relevant data. We collected information on study design, condition under assessment, population characteristics, characteristics of the PRO, and characteristics of the anchor. In addition, we created and applied a new tool to assess credibility of MID estimates. When multiple MIDs were reported for the same PRO across similar clinical conditions, we collected all these estimates.
Results:A total of 5656 citations were retrieved for title and abstract screening of which 1716 were selected for full-text screening and 610 studies reporting on one or more MID estimates proved eligible. We will report on the spectrum and credibility of available MID estimates at the GES.
Conclusion:Our inventory of available MIDs and their associated credibility will be of great use to clinical triallists, systematic review authors, patients and clinicians.