BackgroundThe incidence of severe injury in the geriatric population is increasing. However, the impact of frailty on long-term outcomes after injury in this population remains understudied. Therefore, we aimed to understand the impact of frailty on long-term functional outcomes of severely injured geriatric patients. MethodsWe conducted a retrospective cohort study, including patients ≥65 years old with an Injury Severity Score ≥15, who were admitted between December 2015 and April 2022 at one of 3 level 1 trauma centers in our region. Patients were contacted between 6 and 12 months postinjury and administered a trauma quality of life survey, which assessed for the presence of new functional limitations in their activities of daily living. We defined frailty using the mFI-5 validated frailty tool: patients with a score ≥2 out of 5 were considered frail. The impact of frailty on long-term functional outcomes was assessed using 1:1 propensity matching adjusting for patient characteristics, injury characteristics, and hospital site. ResultsWe included 580 patients, of whom 146 (25.2%) were frail. In a propensity-matched sample of 125 pairs, frail patients reported significantly higher functional limitations than nonfrail patients (69.6% vs 47.2%; P < .001). This difference was most prominent in the following activities: climbing stairs, walking on flat surfaces, going to the bathroom, bathing, and cooking meals. In a subgroup analysis, frail patients with traumatic brain injuries experienced significantly higher long-term functional limitations. ConclusionFrail geriatric patients with severe injury are more likely to have new long-term functional outcomes and may benefit from screening and postdischarge monitoring and rehabilitation services.