A new tool to measure credibility of studies determining minimally important difference estimates for patient reported outcomes

Tags: Oral
Carrasco- Labra A1, Johnston BC2, Ebrahim S2, Furukawa TA3, Patrick DL4, Hemmelgarn BR5, Motaghi Pisheh S1, Dennis B1, Jacobs M6, Vernooij RW7, Fei Y8, Younho Hong B1, Tajika A9, Takeshima N9, Iwakami N9, Hayasaka Y9, Kaminski-Hartenthaler A10, Nussbaumer B10, Colunga L11, Devji T1, Gartlehner G10, Schunemann HJ1, Nesrallah G12, Guyatt GH1
1Department of Clinical Epidemiology & Biostatistics, McMaster University, Canada, 2Department of Anaesthesia and Pain Medicine, The Hospital for Sick Children; Department of Clinical Epidemiology & Biostatistics, McMaster University, Canada, 3Department of Health Promotion and Human Behavior, School of Public Health, Kyoto University Graduate School of Medicine, Japan, 4Seattle Quality of Life Group, Department of Health Services, University of Washington, USA, 5Faculty of Medicine, University of Calgary, Canada, 6Department of Medical Psychology J3-220-1, Academic Medical Center, The Netherlands, 7Iberoamerican Cochrane Centre, Institute of Biomedical Research (IIB Sant Pau), Spain, 8Centre for Evidence-Based Chinese Medicine, Beijing University of Chinese Medicine, Department of Clinical Epidemiology & Biostatistics, McMaster University, China, 9Department of Health Promotion and Human Behavior, Kyoto University Graduate School of Medicine/School of Public Health, Japan, 10Department for Evidence-based Medicine and Clinical Epidemiology, Danube University Krems, Austria, 11Hospital Civil de Guadalajara, Fray Antonio Alcalde, Mexico, 12Nephrology Program, Humber River Regional Hospital; Division of Nephrology, University of Western Ontario, Canada

Background: The ability to interpret and, consequently, include patient-reported outcomes (PROs) in the decision-making process along with other patient-important outcomes relies on the understanding of what improvement or reduction in the PRO represents a change that is important to patients. With such understanding, treatment effects can be understood in terms of their magnitude as large, moderate, small but still important, or negligible. The most common reference point for the interpretation of PROs is the minimal important difference (MID), which provides a measure of the smallest change in a PRO that patients would perceive as an important benefit or harm. Although MIDs are available for many PROs, users of these MIDs have no guidance on how to determine how credible these estimates are.

Objective: To develop an instrument to measure the credibility of MIDs estimates studies.

Methods: We are currently conducting a systematic survey that summarizes and appraises available methods to estimate anchor-based MIDs. We searched MEDLINE, EMBASE, PsycINFO, and CINAHL (1989 to present) to identify studies addressing methods to estimate anchor-based MIDs of PRO instruments or reporting empirical ascertainment of anchor-based MIDs. Teams of two reviewers will independently screen the citations identified, and extract relevant data. We will summarize the available methods and develop a new instrument addressing the credibility of empirically ascertained MIDs. We will user-test and pilot our tool, and assess its inter-rater reliability.

Discussion: Our new instrument will allow users to determine the extent to which the design and conduct of studies measuring MIDs is likely to have protected against misleading estimates. In addition, researchers interested in generating these estimates can learn about key aspects that need to be considered in MID study designs to minimize bias. We will present the methods and final draft of the instrument.