Characteristics of family participants in randomized ICU clinical trials: A systematic review

OBJECTIVES: To describe the demographic characteristics of family participants enrolled in randomized controlled trials (RCTs) of family-centered interventions in the adult intensive care unit (ICU), and to assess how sex, gender, race, and ethnicity were reported, defined, and analyzed. METHODS: This study is a secondary analysis of a previously registered systematic review. A comprehensive search was conducted in MEDLINE, Embase, PsycINFO, CINAHL, and the Cochrane Library up to July 2023, and was updated through October 2025, to identify RCTs of family-centered interventions in adult ICUs. Data were extracted on participant demographics, definitions of sex, gender, race, and ethnicity, and whether these variables were analyzed in relation to study outcomes. RESULTS: Fifty-eight RCTs comprising 12,383 family participants were included. The mean participant age was 51.4 ± 5.6 years; 67 % were women. Spouses or partners (41 %) and adult children (35 %) were the most common relationships to the patient. Race and/or ethnicity was reported in 34 % of studies; among these, 74 % of participants were White. Sex was reported in 66 % of studies and gender in 33 %, though over half conflated the two constructs. Only 26 % and 19 % of studies analyzed outcomes by sex and gender, respectively. CONCLUSIONS: Family participants in ICU clinical trials are predominantly middle-aged women closely related to the patient, with limited racial and ethnic diversity. Reporting of key demographic variables remains inconsistent, constraining interpretation and generalizability. IMPLICATIONS FOR CLINICAL PRACTICE: Standardized and transparent reporting of demographic variables in ICU family research is essential to ensure that family-centered interventions are inclusive, equitable, and generalizable across diverse populations. Improved demographic characterization will enhance both research validity and the delivery of culturally responsive critical care.