This study evaluated the association between arrival time at ED (off-hours vs. working hours) and mortality and surgical intervention among patients with TBI with intracranial injury and found that the off-hour effect was not observed in patients admitted to the level 1 trauma center. However, in the younger group aged < 18 years, mortality was significantly higher during off-hours (adjusted OR [95% CI]: 1.17 [1.04—1.30]). These results suggest that it is still a potential risk factor of TBI-related mortality in young patients, although the off-hour effect did not affect mortality or surgical intervention in the overall study population.
Several studies have shown that patients admitted to the ED at night or during weekends experience poorer clinical outcomes than those admitted during the daytime or weekdays (18–22). This phenomenon is called the “weekend effect” or “off-hour effect,” and it is defined as the differences in clinical outcomes experienced by patients admitted on a weekday versus those experienced by patients admitted during the weekend, or during daytime versus during nighttime. Despite the numerous studies presenting relatively poor clinical outcomes for off-hour-admitted patients, there are various possible explanations for the reason for the off-hour effect, but these are not yet clear (23).
In previous reports, the effect of off-hour ED arrival on hospital mortality was quite heterogeneous according to each disease: cervical trauma (not significant), stroke (not significant), acute kidney injury (OR: 1.07), atrial fibrillation (OR: 1.23), thoracic aortic aneurysm (OR: 2.55), abdominal aortic aneurysm (OR: 1.32), non-traumatic SDH (OR: 1.19), subarachnoid hemorrhage (SAH) (not significant), and intracerebral hemorrhage (ICH) (OR: 1.12) (24–31).
There were three possible explanations for the off-hour effect on mortality. First, human factors might be related to worse prognoses among patients with trauma during off-hours. Emergency physicians have reported negative impacts of shift work, including poor quality of sleep, irritability, fatigue, and mood decrement (32). Second, patients admitted on weekends or at night could have been more critically ill than those admitted during the daytime and on weekdays (33, 34) Third, the off-hour effect could also be an “organization issue” due to the reduced number of staff or levels of staffing (28, 35)
Contrary to the results of previous studies that analyzed the off-hour effect in several diseases, the increase in mortality was not significant in patients with TBI. However, among patients aged 0–17 years, those with TBI who arrived at the ED during off-hours showed higher odds of mortality compared to those arriving at the ED during working hours. To our knowledge, although no studies have assessed the association between pediatric TBI outcomes and time of day or day or week, our study results are consistent with that of a study that reported an off-hour effect on mortality in pediatric patients with trauma (36).
Although there are no existing studies on the reason why pediatric patients with TBI were significantly affected by the off-hour effect, it can be assumed that the lack of resources during off-hours, such as manpower, could have more seriously affected young patients because TBI pathology is age-dependent and young patients with TBI have fewer contusions, whereas severe brain injuries such as SDH and diffuse cerebral edema are more common (37).
In the subgroup analysis of traumatic SDH, which was judged to have been largely affected by the off-hour effect due to the need for surgical treatment, no off-hour and no interaction effects with age group were observed. This is consistent with the results of previous studies that reported the weekend effect in patients with trauma with SDH, which demonstrated that patients admitted over weekends had similar mortality despite higher severity compared to patients admitted on weekdays (14).
In this study, the off-hour effect was significantly associated with mortality at hospital discharge in the young patients with TBI. Our study results suggest the possibility that the quality of treatment may still differ depending on arrival time at the ED in a specific patient group, although efforts are being undertaken to improve healthcare delivery to reduce the gaps in healthcare outcomes, regardless of whether patients are admitted during the daytime, nighttime, or on weekends. To reduce the TBI burden, especially in young patients, hospitals and EDs should be designed with consideration of the allocation of resources so that patients can expect the same standard of emergency care regardless of the day and time of admission.
This study has several limitations. First, 0–17 years was set as the younger age group, but it may not be appropriate to have this wide of an age range because of the large physiological differences between the ages. Second, depending on the medical condition, TBI severity, and type of brain hemorrhage, the required treatment is different; therefore, the effect sizes of the off-hour effect may be different, but this was not taken into account. A subgroup analysis of SDH generally requiring surgical intervention has been performed, but it is still insufficient. Finally, the study design was not a randomized controlled trial. Thus, there may be significant potential biases that were not controlled.