Physical restraint use in a United States intensive care unit—a retrospective cross sectional, single center cohort study from 2008 to 2022

Background: Physical restraints are widely used in intensive care units (ICUs) despite uncertain clinical benefit and risks. We aimed to characterise patterns of restraint use, demographic and clinical predictors, and temporal trends before and after introduction of federal restraint-related reporting requirements. Methods: We conducted a retrospective cross-sectional study of 51,838 adults admitted to ICUs at Beth Israel Deaconess Medical Center, Boston, MA, USA, between 2008 and 2022, using data from the Medical Information Mart for Intensive Care IV (MIMIC-IV) electronic health record repository. Primary outcome was the proportion of ICU days with documented physical restraint use. Associations between restraint use and demographic and clinical factors were estimated using a binomial generalised linear model with a logit link. Propensity score matching compared Black and White patients under varying adjustment specifications. Findings: Among 51,838 patients (mean age 63.8 years; 57% male), 21,091 (40.7%) experienced restraint. Use increased from 36.9% in 2008-10 to 44.0% in 2020-22 (p < 0.0001). Asian (aOR 0.84, 95% CI 0.79-0.89) and Hispanic/Latino patients (aOR 0.87, 95% CI 0.83-0.92) had lower odds of restraint than White patients. Propensity score matching between Black and White patients revealed ethnic patterns were highly sensitive to model specification: excluding demographic characteristics revealed significant disparities, which were attenuated when psychiatric diagnoses were also excluded. Matched White patients were not representative of all White ICU patients but rather a subset resembling Black patients on observed characteristics. Interpretation: Restraint practices appear to vary with patient acuity, institutional factors, and communication barriers. The sensitivity of ethnic disparities to psychiatric diagnosis adjustment suggests these diagnoses may function as mediators rather than confounders, potentially reflecting systematic differences in clinical assessment along the causal pathway between ethnicity and restraint decisions. The non-representativeness of matched cohorts underscores that disparities depend on which patient subgroups are compared. Prospective multisite studies with standardized assessment protocols are needed to validate findings, disentangle true clinical variation from systematic bias and provide a more comprehensive understanding of restraint practices across US ICU settings. Funding: No study-specific funding was received.