This study is the largest epidemiological study of pediatric head trauma in Scandinavia, including more than 5000 children. It showed that pediatric head trauma is a common cause of ED visits in southern Sweden. The rates of CT-scanning and admissions and the incidence of ICI were lower than those reported in studies conducted outside of Scandinavia (4, 8, 20). MHT patients had a significantly higher rate of ICI, more frequently underwent CT-scans, and had higher hospital admission rates than pediatric patients with IHT. These observations indicate that they are separate entities that possibly should be managed using separate guidelines to optimize the use of CT-scans.
The incidence of ED visits due to head trauma in our study was lower than those reported in studies from England, Wales, and the United States(6, 7). These differences could be explained by differences in organization and funding of health care systems that lead to different thresholds for visiting EDs for minor injuries. Other reasons could be differences in safety awareness by parents and differences in mandatory safety measures between countries, leading to fewer and less severe traumas. Such safety measures include laws on blood alcohol concentration limits and laws requiring children to use seatbelts in the back seat of cars and wearing helmets while cycling(21).
The incidence of TBI is difficult to study because of its indistinct definition. Therefore, we decided to study the incidence of ICI since it has a clear and straightforward definition that makes comparisons between studies easier. The rate of ICI was lower in our study than those in previous international studies that reported the rate of TBI on CT, which is equivalent to our definition of ICI(4, 8). The relatively low rate of ICI in the present study may to some extent be explained by differences in aims, definitions and inclusion criteria of the studies. The present study aimed to describe the epidemiology and the management of all children attending an ED due to head trauma. Other studies, such as the PECARN trials (4), aimed to derive CDRs to assist clinicians in the decision whether to perform head CT-scan, and therefore excluded children with trivial head traumas. Our choice to include all patients with head trauma, irrespective of the severity of the trauma, may have resulted in a relatively higher proportion of patients with minor head trauma.
We found that falls were the most common trauma mechanism in patients with IHT. This observation is consistent with results from previous international studies, except for some studies reporting MVA as a common trauma mechanism for TBI(5). In the present study, MVA was the trauma mechanism in only 1.2% of patients with IHT; however, it was the most common trauma mechanism in patients with MHT. The discrepancies in trauma mechanisms between studies can be explained by the differences in inclusion criteria and variations in the overall incidence of MVA in different countries(22).
The frequencies of CT-scanning of the head and admissions to a hospital ward were lower than those reported in several previous studies(4, 8, 20). The relatively high CT-scanning rate in these studies may to some extent be explained by the exclusion of patients with “trivial” head trauma from their study populations(4, 23). An alternative explanation could be less liberal CT-scanning in the present study. Although the rate of CT-scans was comparably low in our study, it was still approximately eight times higher than the rate of ICI. The relatively high rate of negative CT-scans raises the question of whether it is possible to reduce the use of CT-scanning further as it is associated with a risk for future malignancies(9). Hospital admission and clinical observation of the patients is an alternative and equally safe measure to CT-scans in cases deemed to have a low risk for ICI, but admission costs are higher than those of performing CT-scans and discharging patients early(24). We argue that admission may be the ethically preferable option in cases where the risk for ICI is low but cannot be ruled out with certainty. One would expect the admission rate to be higher in our study to compensate for the relatively conservative use of CT-scans, but the admission rates were similar or lower compared to previous studies(4, 8, 20).
The rates of ICI and NI in the present study were lower than those reported in previous studies.(4, 23) A contributing factor to the differences could be that we included more patients with less severe trauma. It is also possible that the low rates of ICI observed in the present study may be due to the relatively low CT-scanning rates, where minor ICIs may have remained undiagnosed. Other possible reasons may be mandatory safety measures for children in Sweden leading to less severe injuries and the fact that the incidence of traffic accidents with and without injuries and fatalities is lower in Scandinavia compared with the rest of Europe and North America(22).
In comparison with children with IHT, the relative risks of undergoing CT-scans of the head to be admitted to a hospital ward or an ICU were significantly higher in patients with MHT. Similarly, the relative risk of ICI and NI was significantly higher in MHT patients. The higher frequency of CT-scans of the head is likely explained by the assumed higher levels of trauma energy that MHT patients commonly are exposed to. These observations suggest that children with MHT represent an entity distinct from that of patients with IHT. Consequently, to reduce the number of excessive CT-scans in patients with IHT, we believe it is important to have separate management strategies for children with MHT and IHT.
The retrospective nature of data collection is the most relevant limitation of the present study. There is a risk of information bias which prevents us from drawing more than cautious conclusions from this study. Despite our countermeasures, another limitation is using of five different data collectors and the associated risk for differences in interindividual data interpretation.