Minimal important change and difference in health outcome: An overview of approaches, concepts, and methods

Objective: To provide an overview of approaches, concepts, and methods used to define and assess minimal important change and difference in health outcome. Method: A narrative review of the literature, guided by a conceptual framework. Results: We distinguish between (i) interpretation of health outcome in individuals versus groups, (ii) change within individuals or groups versus difference between change within individuals or groups; and (iii) the responder approach (based on the proportion of patients that obtain a defined response) versus the group average approach (based on the average amount of change in a group). We review approaches, concepts, and methods. Conclusion: By bringing together and juxtaposing various approaches, concepts, and methods, we set a precursory step in the direction of consensus building in the field concerned with defining and assessing minimal important change and difference in health outcome. We emphasize the need for conceptual clarification and terminological standardization. We argue that assessing minimal importance of change and difference in health outcome is essentially a value judgment involving a range of considerations and perspectives.