Abstract
BACKGROUND: Equity is a key priority in UK health and social care policy, yet its integration into adult social care trials remains unclear. Without adequate inclusion or analysis of underserved populations, interventions risk reinforcing health inequalities. AIM: To examine how equity-relevant characteristics - defined by CORE20PLUS5 and PROGRESS-Plus -are reported, categorised, and analysed in UK trials of adult social care interventions. METHODS: A systematic review of five databases (PubMed, MEDLINE, Embase, CINAHL, Web of Science) was conducted for studies published between January 2015 and June 2025. Eligible studies involved UK-based adult populations (≥ 18 years) and used trial or quasi-experimental designs. Data were narratively synthesised due to heterogeneity. Study quality was assessed using Joanna Briggs Institute tools. RESULTS: Fourteen studies met inclusion criteria. All reported at least one equity characteristic, but reporting was inconsistent. Ethnicity was often grouped into broad categories, limiting subgroup analysis. Few studies targeted underserved populations or designed interventions to address inequity. Reporting gaps included gender identity, sexual orientation, immigration status, and literacy. CONCLUSIONS: Equity considerations are limited in UK adult social care trials. Future research should embed equity frameworks, improve reporting detail, and conduct subgroup analyses to ensure interventions are inclusive and effective across all population groups. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12913-026-14347-y.