The volume-outcome relationship in trauma centers is well established, including geriatric volume. With an increasing geriatric population, it remains unclear whether a tipping point exists for these complex patients who overwhelm centers. Our objective was to evaluate whether the proportion of geriatric patients relative to total volume impacts outcomes. This retrospective cohort study analyzed patients aged >15 years from the Trauma Quality Program Patient Use File dataset between the years 2017 and 2021. We calculated the center-level annual geriatric proportion of total adult patient volume. Generalized additive mixed models evaluated nonlinear effects between geriatric proportion and mortality for geriatric and nongeriatric patients adjusted for demographics, vitals, injury characteristics, center characteristics, frailty, and comorbidities. We included 3,989,267 patients from 605 centers. Increasing geriatric proportion was associated with improving mortality for geriatric patients until reaching thresholds of 65% of total volume, where mortality plateaued. Importantly, at a geriatric proportion of 61%, mortality for nongeriatric adults began to increase (adjusted odds ratio per 5% increase: 1.04; 95% confidence interval: 1.01-1.08). Geriatric Charlson Comorbidity Index was related to nongeriatric mortality in the highest quartile of geriatric proportion (adjusted odds ratio: 1.18, 95% confidence interval: 1.11-1.25). Center-level geriatric proportion is an important predictor of both geriatric and nongeriatric trauma outcomes. At higher proportions of geriatric patients, the loss of the volume-outcome benefit and even increase in mortality suggests the medically complex geriatric population may overwhelm centers, leading to worse outcomes among all patients. These findings may inform trauma system planning to optimize care of our geriatric and nongeriatric patients.
Boland et al. (2025) studied this question.