Aging at the Cellular Level: An Exploratory Analysis of the Effect of Age on Platelet Dynamics in Injured Patients

INTRODUCTION: Increasing chronological age drives dynamic changes in platelet functionality, bringing unique biologic challenges to the injured older adult. While platelets play an indispensable role in injury response, the impact of age on platelet dynamics after injury remains elusive. We examine the associations of age and platelet dynamics for injured patients not on antiplatelet therapy, hypothesizing that aging is associated with decreases in platelet count and function in injured patients. METHODS: We performed a secondary analysis of injured patients from a prospective observational study of coagulation and inflammation (2010-2024). Patients taking anticoagulants, antiplatelets, and/or with isolated traumatic brain injury were excluded. Univariable and multivariable associations of age and platelet count and function profiles (impedance aggregometry and viscoelastic testing) at presentation and up to seven days post-injury were analyzed. Platelet profiles, thromboembolic events, and mortality relationships were analyzed by stratifying age to <55 and ≥55 years. RESULTS: 716 patients were examined. Median age was 36 years (range 15-97 years). On multivariable analyses platelet count and functional profiles demonstrated independent associations with increasing age at all time points measured - reduced platelet count, aggregation responses, and hypercoagulable clotting dynamics. In patients ≥55 years low platelet count and reduced aggregation responses on presentation were suggestive of increased mortality (all p<0.05). CONCLUSION: Following injury, increasing chronological age is independently associated with altered platelet profiles - reduced platelet count and aggregation responses with concurrent hypercoagulable clotting dynamics. These age-related cellular changes may portend worse outcomes, including mortality, and should be considered for intervenable biologic targets in future study.