Background The study aimed to synthesize participant retention-related data for longitudinal follow-up studies of survivors from trauma intensive care units (ICUs).Methods Within a published scoping review evaluating ICU patient outcomes after hospital discharge, two screeners independently searched for trauma ICU survivorship studies.Results There were 11 trauma ICU follow-up studies, all of which were cohort studies. Twelve months (range: 1–60 months) was the most frequent follow-up time point for assessment (63% of studies). Retention rates ranged from 54% to 94% across time points and could not be calculated for two studies (18%). Pooled retention rates at 3, 6, and 12 months were 75%, 81%, and 81%, respectively. Mean patient age (OR 0.85 per 1-year increase, 95% CI 0.73 to 0.99, p=0.036), percent of men (OR 1.07, 95% CI 1.04 to 1.10, p=0.002), and publication year (OR 0.89 per 1-year increase, 95% CI 0.82 to 0.95, p=0.007) were associated with retention rates. Early (3-month) versus later (6-month, 12-month) follow-up time point was not associated with retention rates.Discussion Pooled retention rates were >75%, at 3-month, 6-month, and 12-month time points, with wide variability across studies and time points. There was little consistency with reporting participant retention methodology and related data. More detailed reporting guidelines, with better author adherence, will help improve reporting of participant retention data. Utilization of existing research resources may help improve participant retention.Level of evidence Level III: meta-analyses (post-hoc analyses) of a prior scoping review.