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

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.

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.

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.

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.

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.