Results from this study showed that the incidence of unintentional injury in rural children was 20.1% which is higher than the early reports for rural children aged 5 to 16 and left behind children in China [28, 29]. Perhaps one reason is that in the case group 55.4% primary caregiver are grandparents who have poor health status and they are not suitable for supervising children. They also lacked knowledge and skills on prevention for injury. Once children suffered unintentional injury, they couldn’t respond and take correct first aid on time [29, 30]. Another reason is that different regions have different social and economic development levels. The gross domestic product (GDP) of Hei Longjiang Province is low in China [31]. The environmental facilities are not safe and the travel transport of rural areas mainly rely on the electric vehicles and agricultural locomotives [32], the fall and accidental injury are the most common unintentional injury in this study. Rural household prefer to keep animals (e.g. dog, cat, goose) protecting their courtyards, so the animal bites injury in childhood are usual. Hei Longjiang province is located in the northeast of China and its winter season is too long. the rural households need to make fires for heating, drinking water, cooking and other daily activities, so children are prone to burns [33]. Previous studies showed that boys were more likely to experience injury than girls in all age groups [34, 35]; however, there was no significant difference between boys (50.2% %) and girls (49.8%) in the case group in this study. This could be the result of different parenting patterns between boys and girls because boys are more often punished by their parents when they had risk-taking behaviors, whereas these mistakes or risk-taking behaviors would be tolerated in girls [36, 37].
Findings from this study indicated that the number of risk factor index in the case group was more than the control group. The most distribute RFI in the case group were 1(35.4%) and 2 (20.5%), while there were 0 (47.8%) and 1 (35.7%) in the control group. Among rural children, the RFI of unintentional injury is greater than the PFI, while the lack of protection factor is the cause of unintentional injury. The aim of this research is to explore the single effect and cumulative effect of risk factors (children's behavior, parents' risk perception) and protection factors (parental supervision, parents' first aid knowledge, attitudes and skills, family environment) on the occurrence of unintentional injuries. The more prominent the children's behavioral problems and harm behaviors have, the greater parents perceived of injury risk, the more severity of childhood injury. Moreover, the children's behavioral problems and risk-taking behaviors can predict the occurrence of unintentional injury [38].Children with behavioral problems have a high incidence of unintentional injuries. Children's behavioral problems have predictive effects on children's unintentional injuries, especially those with behavioral problems such as antisocial, aggression, anxiety/depression, hyperactivity and discipline violation [13]. The results of binary logistic regressions found that with the increased number of RFI, the risk of unintentional injury didn’t add up simply, but emerged multiple growth, for example, the risk occurrence of unintentional injury was 1.76 times when RFI was 2 than RFI was 1, the risk of unintentional injury was 3 times when RFI was 3 than 2. What’s more, the protective factors were found to lead to the occurrence of unintentional injury. The cumulative effect on co-occurring and multiple risk or protection factors have been concluded in children and adolescent’s behavior problems which indicate the more risk factors they are exposed to, the worse the outcome is [15, 40, 41]. The cumulative effect of risk factors and protection factors played an important role in childhood unintentional injury. The linear regression analysis indicated that risk factors and protection factors had interactive effect to each other, protection factors could regulate the effect of risk factors, and with the increased number of protection factors, the effect of risk factors will be weakened.
The current study is the first to describe the relationship between exposure to cumulative effects of multiple risk/protection factors and unintentional injury in rural children through the nested case-control study. It contributes to a new view point to the risk factors and prevention strategies for the occurrence of rural childhood unintentional injury in China. Specifically, it reveals significant cumulative effect of risk and protection factors in the rural childhood injury. However, the findings still have several limitations. First, all the data were came from a longitudinal database, only a few risk factors and protection factors were investigated, some more important factors may be missed. More protection factors should be found as the cumulative effect in the future study. Second, the data were collected from primary caregivers, but social bias and recall bias would be existed when filling out the questionnaires, which could not stand for the real condition of the primary caregivers and the children. Third, the children mainly suffered from minor injury in this study who were assessed by the primary caregiver themselves. They may overestimate or underestimate the injury. Thus, the severity of injury should be recorded by medical workers or refer to the standard degree for further study. Last, the participants were all from elementary and junior schools in 3 rural regions of Hei Longjiang Province, the findings might not be generalizable to other areas of China.