Predicting Outcomes in Traumatic Brain Injury Using the Glasgow Coma Scale: A Joint Modeling of Longitudinal Measurements and Time to Event

Background Traumatic brain injury (TBI) is an important public health problem throughout the world. Objectives The aim of this study was to assess repeated glasgow coma scale (GCS) scores in predicting the severity of TBI and patients’ survival. Patients and Methods In this longitudinal study used a total sample of 239 patients, all of whom were hospitalized with traumatic brain injuries. Subjects were selected by simple random sampling in intensive care unit (ICU) wards of the Shahid Beheshti hospital in Kashan, Iran between September 2008 and September 2010. The patients’ level of consciousness was evaluated using GCS at admission, six hours after admission to the ICU, and at the time of discharge from the hospital. A Glasgow outcome score (GOS) is used to classify the global outcomes in TBI survivors. A joint modeling approach was utilized for data analysis using R software. Results The results showed that female patients had the risk of occurrence, slightly more than men, but this was not significant (HR =1.095 P = 0.757). The mortality risk was significantly higher in older patients (HR = 1.010, P = 0.010). In addition, the results indicated a significant increasing linear trend in GCS values over time (HR=1.78, P=0.003). Higher age was also associated with lower GCS values over time (P < 0.001). The severity of TBI decreases with increasing GCS values (P < 0.001). Conclusions By jointly modeling longitudinal data with time-to-event outcomes, our findings supported the use of the GCS scores in predicting the severity of TBI.