RT Journal Article SR Electronic T1 A realist review of how, why, for whom and in which contexts quality improvement in healthcare impacts inequalities JF BMJ Quality & Safety JO BMJ Qual Saf FD BMJ Publishing Group Ltd SP bmjqs-2024-017386 DO 10.1136/bmjqs-2024-017386 A1 Johnson, Lucy Lara A1 Wong, Geoff A1 Kuhn, Isla A1 Martin, Graham P A1 Kapilashrami, Anuj A1 Lennox, Laura A1 Black, Georgia Bell A1 Hill, Matthew A1 Swiers, Ryan A1 Mahmood, Hashum A1 Jones, Linda A1 Beng, Jude A1 Ford, John YR 2025 UL http://qualitysafety.bmj.com/content/early/2025/01/19/bmjqs-2024-017386.abstract AB Introduction Quality improvement (QI) is aimed at improving care. Equity is one of the six domains of healthcare quality, as defined by the Institute of Medicine. If this domain is ignored, QI projects have the potential to maintain or even worsen inequalities.Aims and objectives We aimed to understand why, how, for whom and in which contexts QI approaches increase, or do not change health inequalities in healthcare organisations.Methods We conducted a realist review by first developing an initial programme theory, then searching MEDLINE, Embase, CINAHL, PsychINFO, Web of Science and Scopus for QI projects that considered health inequalities. Included studies were analysed to generate context-mechanism-outcome configurations (CMOCs) and develop an overall programme theory.Results We screened 6259 records. Thirty-six records met our inclusion criteria, the majority of which were from the USA. We developed CMOCs covering four clusters: values and understanding, resources, data, and design. Five of these described circumstances in which QI may increase inequalities and 15 where it may reduce inequalities. We found that QI projects that are values-led and incorporate diverse, patient-led data into design are more likely to address health inequalities. However, when staff and patients cannot engage fully with equity-focused projects, due to practical or technological barriers, QI projects are more likely to worsen inequalities.Conclusions The potential for QI projects to positively impact inequalities depends on embedding equity-focused values across organisations, ensuring sufficient and appropriate resources are provided to staff delivering QI, and using diverse disaggregated data alongside considered user involvement to inform and assess the success of QI projects. Policymakers and practitioners should ensure that QI projects are used to address inequalities.Data are available upon reasonable request.