Introduction: The Glasgow Coma Scale (GCS) is the primary method of assessing consciousness after traumatic brain injury (TBI). There is scant literature discerning the influence of circadian rhythms or emergency department (ED) admission hour on this important clinical tool.
Methods: Retrospective cohort analysis of blunt adult TBI using the National Sample Program of the National Trauma Data Bank (2003-2006). ED admission GCS was characterized by midday (10am-4pm) and midnight (12am-6am) cohorts (N=24,548). Multivariable regression was performed to assess associations between arrival hour and GCS. Statistical significance assessed at p<0.05.
Results: Patients were 43.5±19.9 years old and 69.5% male. GCS was 12.63±4.20 (median 15, IQR 13-15; 77.2% mild, 5.2% moderate, and 17.6% severe TBI). Overall, 85.7% were admitted to hospital (33.5% ICU). ISS was 15.65±11.22 and did not differ between day/night.
Nighttime admissions were associated with decreased medical comorbidities (p<0.001). GCS demonstrated a circadian pattern with peak at 12pm (13.03±0.08(SE)) and nadir at 4am (12.12±0.12(SE)). Midnight patients demonstrated significantly lower GCS (12am-6am: 12.23±0.04, 10am-4pm: 12.95±0.03, p<0.001). Multivariable regression adjusted for age, mechanism, comorbidities, hypotension and ISS confirmed that midnight-hours were independently associated with decreased GCS (B=-0.29 [-0.40,-0.19]).
In patients who did not die in ED or go directly to surgery (N=21,862), multivariable regression demonstrated midnight-hours (OR 1.73 [1.30-2.31]) associated with increased likelihood of ICU admission, while increasing GCS (per-unit OR 0.82 [0.80-0.83]) associated with decreased odds. Notably, the interaction factor GCS*ED arrival hour independently demonstrated an of OR 0.96 [0.94-0.98], suggesting that the influence of GCS on ICU admission odds is less important at night than during the day.
Conclusions: Nighttime TBI patients present with decreased GCS and are admitted to ICU at higher rates, yet have fewer prior comorbidities and similar systemic injuries. The interaction between nighttime hours and decreased GCS on ICU admissions has important implications for clinical assessment/triage.
Patient Care: This research is the first to explore the potential of circadian effects associated with GCS assessment following TBI using a large, population-based retrospective database. The analysis highlights the need for careful evaluation of level of consciousness of TBI patients admitted at mid-day or mid-night hours as part of the decision for hospital admission and optimal utilization of healthcare resources.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the relevance of circadian rhythm considerations on Glasgow Coma Scale (GCS) evaluation for traumatic brain injury (TBI) patients; 2) Discuss the independent effect of nighttime admissions on emergency department GCS after TBI; 3) Identify implications for the assessment and triage for TBI patients admitted at night.