Impaired consciousness is present in many injured patients. Efforts are directed to evaluate the depth of consciousness in these patients for proper management and prediction. The aim of the study was to compare the GCS and FOUR scores and to verify their ability to predict outcomes in TBI coma patients outside the hospital setting.
Since 1974 , when the GCS was introduced, the GCS has been widely used in the prehospital setting. In 2005, the FOUR score  was proposed to reduce some limitations of the GCS. Currently, the FOUR score is mostly employed in intensive and neurological care units.
The advantages of the FOUR score have been assessed by Wijdicks et al. , especially in neurologically critically ill patients who are intubated. When we compared the GCS and FOUR scores, we noticed a key difference: the verbal response is not an intrinsic part of the FOUR score. Taking this into consideration, the FOUR score is very useful in intubated patients . Intubation is a common procedure after injury. The FOUR score tests essential brainstem reflexes and provides information about the degree of brainstem injury that is not registered with the GCS. The FOUR score can distinguish a locked-in syndrome and a possible vegetative state  and includes signs suggestive of uncal herniation . The evaluation of respiratory patterns in the FOUR score may also add information about the presence of respiratory drive . Studies have also shown that the in-hospital outcomes between the scales were better for the lowest total FOUR scores than for the GCS scores . Conclusions obtained in previous studies have shown that the FOUR score is an accurate predictor of outcome in TBI patients , that it has some advantages over the GCS  and that it can be performed in a variety of ICU contexts . The FOUR score is easily taught and simple to administer, and it provides essential neurologic information that allows for an accurate assessment of patients with altered consciousness with excellent interrater agreement among medical intensivists . The FOUR score might be a better prognostic tool for ICU outcomes than the GCS, most likely because it integrates brainstem reflexes and respiration . Other studies have shown the predictive value of the FOUR score on admission in patients after moderate and severe TBI . These studies also showed that the predictive ability for the primary outcome 2 weeks after injury was no better than that with the GCS score . For nontraumatic comatose patients, different parameters as predictors of outcome in the prehospital environment were also studied .
Analyses performed between the GCS and FOUR scores in the hospital environment have demonstrated that the GCS is missing the key essential elements of a comprehensive neurological examination for comatose patients . In the same study, it was confirmed that the FOUR score maintained simplicity and, at the same time, provided far better information . Other previous studies have demonstrated that the GCS and FOUR scores show comparable results in the assessment of patients with traumatic brain injury . These data show that there are excellent statistical correlations between the two scoring systems . Moreover, these studies show that the FOUR score provides better details regarding the neurological status of patients . The results can be considered clinically relevant because of the strong statistical association obtained as well as the agreement in the literature . Overall, there are currently multiple scores used to determine the prognosis of patients in intensive care units. However, a scoring system should be simple, reliable, and predictive of morbidity and outcome.
Due to the different categories of scores, the FOUR score is more effective in evaluating patients who are unconscious and dependent on mechanical ventilation. Prospective studies with larger cohorts of patients treated in various intensive care units for longer durations are needed to evaluate whether the application of these scales influences functional and cognitive outcomes .
In addition, further comparative neurological outcome studies also showed that the outcome of patients admitted to the ICU was significantly higher when the GCS or the FOUR score was used . Discrimination was fair for both scores, but the FOUR score was superior to the GCS . Calibration was better for the FOUR score than for the GCS in the ICU . The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were also better for the FOUR score than for the GCS . Good correlation was observed between the two scores .
A comprehensive overview of the relationship between a patient’s FOUR score and outcome is still lacking. A recent study on the FOUR score showed that the FOUR score had a close overall relationship with in-hospital outcomes and poor functional outcomes in patients with impaired consciousness . This research also claimed that there was insufficient evidence to determine whether performance was modified in different groups, and there was some suggestion that the assessment of brainstem reflexes and respiratory patterns made less of a contribution than eye and motor scores .
In the present study, our data showed no statistically significant difference in terms of the correct prediction of outcome 24 hours after the injury. We found no statistically significant differences in the Youden index or area under the ROC curve after 24 hours, no statistically significant differences one month after the injury, and no statistically significant differences three months after the injury.
In our opinion, we should obtain a better understanding of the anatomical and pathophysiological pathways that are not evidenced by certain GCS and FOUR scores. Further research should be focused on the comparison between the obtained GCS and FOUR score data and the anatomical substrate changes revealed by diagnostic tools such as head CT scans and brain fMRI. With these data, we could obtain the accurate subanatomical and clinical information needed to perform specific invasive therapy to lead to a far better outcome for patients.