Effect of Age on the Association Between the Glasgow Coma Scale and the Anatomical Brain Lesion Severity: a Retrospective Multicentre Study.

Background and importance Older adults are at higher risk of undertriage and mortality following a traumatic brain injury (TBI). Early identification and accurate triage of severe cases is therefore critical. However, the Glasgow Coma Scale (GCS) might lack sensitivity in older patients. Objective This study investigated the effect of age on the association between the GCS and TBI severity. Design, settings, and participants This multicentre retrospective cohort study (2003-2017) included TBI patients aged ≥16 years with an Abbreviated Injury Scale (AIS of 3, 4 or 5). Older adults were defined as aged 65 and over. Outcomes measure and analysis Median GCS score were compared between older and younger adults, within subgroups of similar AIS. Multivariable logistic regressions were computed to assess the association between age and mortality. The primary analysis comprised patients with isolated TBI, and secondary analysis included patients with multiple trauma. Main results A total of 12 562 patients were included, of which 9485 (76%) were isolated TBIs. Among those, older adults represented 52% ( n  = 4931). There were 22, 27 and 51% of older patients with an AIS-head of 3, 4 and 5 respectively compared to 32, 25 and 43% among younger adults. Within the different subgroups of patients, median GCS scores were higher in older adults: 15 (14-15) vs. 15 (13-15), 15 (14-15) vs. 14 (13-15), 15 (14-15) vs. 14 (8-15), for AIS-head 3, 4 and 5 respectively (all P  < 0.0001). Older adults had increased odds of mortality compared to their younger counterparts at all AIS-head levels: AIS-head = 3 [odds ratio (OR) = 2.9, 95% confidence interval (CI) 1.6-5.5], AIS-head = 4, (OR = 2.7, 95% CI 1.6-4.7) and AIS-head = 5 (OR = 2.6, 95% CI 1.9-3.6) TBI (all P  < 0.001). Similar results were found among patients with multiple trauma. Conclusions In this study, among TBI patients with similar AIS-head score, there was a significant higher median GCS in older patients compared to younger patients.