The current study demonstrated that deaths following a trauma follow the classical tri-modal pattern in low resource countries and pre hospital care is rarely available for victims of road traffic injuries. Free ambulance transportation was in-available for trauma victims resulting in delay in hospital arrival for accidents sustained on rural roads. Being a driver, accident location at rural areas, low systolic blood pressure and low GCS on admission, injury site and interaction of providing pre hospital care and long distance were found to be predictors of time to death among road traffic injury victims.
The classical tri-modal distribution of trauma deaths was described by Trunkey in 1983 (35). Different previous studies had disproved this traditional distribution of mortalities due to the main reduction in the number of early and late hospital deaths (36). Our study demonstrated that road traffic injury mortality still followed the traditional tri-modal pattern. According to the current study, there were two peaks, one in the first 24 hours and the second at the end of the first week of the injury. Nearly half of the deaths occurred in the hospital after a week of admission. A similar finding was reported by a study conducted at Iran showing two peak times of trauma deaths (28). Poor operative services for severe head injury cases and lack of intensive care unit for severely injured victims could explain the reason for late deaths in our hospital (37). The surgical set up in our case is not optimum to perform surgical intervention for severely injured head injury victims. Besides, there is no well-equipped surgical ICU service to support victims with ventilatory failure. On the other side, the in-availability of pre-hospital basic life support care could have resulted in clinical deterioration of victims that could result in late complications (8).
In this study, none of the victims received pre-hospital care at the scene of injury. This is consistent with previous studies that showed pre-hospital emergency care is under-served or unavailable in most low and middle-income countries (38, 39). The finding is also consistent with a study conducted in Addis Ababa where none of the victims got pre-hospital care (15). The current study also indicated that full package Ambulance service was unavailable for all the victims and only 20% received transportation service without trained personnel accompanying the victims. Our finding is in line with a systematic review indicating Ambulance service was under served in many low and middle income countries (40) and a study conducted in Pakistan that reported majority of participants didn’t want to call Ambulance for emergency cases because the Ambulances didn’t function properly (41). On top of this the available ambulance service was not for free, and victims or the family have to cover cost for fuel and per Diem of drivers. Similar finding was reported from Cambodia (42).
The current study also showed that many trauma victims who were referred from primary hospitals would have been treated at those hospitals. This is in line with a study conducted at Southern India, which showed that trauma care was unnecessarily delayed and liable for unnecessary referrals due to poor resources for trauma case management (30) and another study demonstrated that there are many deficiencies in emergency care services ranging from in-availability of drugs and lack of trainings to provide the required emergency care (43).
According to our study, the overall incidence of road traffic injury deaths was 29 per 100,000 hours of observation. This finding is higher when compared with a study conducted at Tikur Anbessa Hospital, Addis Ababa, which was 10/100,000 hours of observation (15). The discrepancy could be explained by the fact that the Tikur Anbessa Hospital has a better trauma management setup including an intensive care unit (ICU). Hence the quality of care could explain the lesser death at the Tikur Anbessa Hospital (23). Other explanation could be due to the fact that follow up continued after discharge from hospital in the current study, while the mentioned study didn’t follow victims after discharge that ignored deaths at home after discharge.
The study revealed that pedestrians are the most frequently affected road user categories as compared to passengers and drivers. This is in line with the federal police commission report (44) and studies conducted in the capital city, Addis Ababa, (45, 46) all showing pedestrians to be the road user categories most frequently affected by RTI. But severe and fatal injuries were more likely to occur among drivers and passengers in our study. This finding was consistent with previous study that indicated fatal injuries were more likely among drivers and passengers (47) but in contradiction to findings in a study that showed pedestrians are more likely to die from a vehicle accident (48).
Our study demonstrated that accidents that were sustained in rural areas were more likely to result in a fatal outcome than those at the urban location. Our finding is consistent with a study conducted by Craig Zwerling and colleagues that showed injury severity and fatality was more than three times higher at rural area than urban areas (49). This could be explained by the fact that most areas of the rural residence lack health care facility and transport access to reach the hospital timely resulting in mismanagement and delays of care. This will, in turn, result in bad outcomes (50). The other possible explanation for the increased mortality in rural residence could be the fact that vehicles are very speedy in the rural areas as a result of poor traffic control. Studies showed that accident intensity increases when a crash is caused by a speedy vehicle (51).
Low systolic blood pressure on admission was significantly associated with time to death among road traffic injury victims. This finding is in line with previous studies that showed victims with low blood pressure on admission were more likely to experience death than their counter parts (14, 52–53). This can be explained by the fact that acute blood loss is very likely in trauma patients that had brought the drop in systolic blood pressure (54). Low systolic blood pressure could increase mortality via poor organ perfusion and consequent organ failure (55). Besides, acidosis from poor perfusion and late complications as nosocomial infection and sepsis are also very likely to occur in patients with hemorrhagic shock (56, 57). These are the possible explanations for low systolic blood pressure and increased mortality.
The current study revealed that hospital arrival time is associated with 30 days of mortality following a road traffic injury. Accordingly, victims who arrived at the hospital between one to four hours were more likely to die than those who arrived within one hour of injury and beyond 4 hours of injury. This is contrary to the concept of the "Golden hour" of trauma that depicts the outcome of trauma was better when victims arrive within one hour of injury (58–59). This could be explained by the fact that victims who are seriously injured and have non-survivable injuries were more likely to be directly transferred to hospital immediately after injury than less severe injury cases, thus increasing the death rate among victims who arrived within 60 minutes of injury.
The study showed an interaction between long distance from the hospital and pre-hospital first aid to be significantly associated with 30 days mortality following a road traffic injury. The possible explanation for this finding could be due to delays in definitive care. Though essential trauma care is vital to treat time-sensitive issues such as airway compromise and severe bleeding, delayed patient transfer, and delays in definitive care also endanger the life of trauma victims (60). This is particularly the case in low resource countries like Ethiopia where the majority of primary hospitals are not in a position to provide essential trauma care (61).