Contextual Determinants of Childhood Injury: A Systematic Review of Studies With Multilevel Analytic Methods

The definition of injury that underpins the contemporary approach to injury prevention is an etiological definition relating to bodily damage arising from transfer of energy to tissues of the body beyond the limits compatible with physiological function. Causal factors proximal to the energy transfer are nested within a more complex set of contextual determinants. For effective injury control, understanding of these determinants is critical.

The primary aims of this study were to describe the area-level determinants that have been included in multilevel analyses of childhood injury and to quantify the relationships between these area-level exposures and injury outcomes.

We conducted a systematic review of peer-reviewed, English-language literature published in scientific journals between January 1997 and July 2014, reporting studies that employed multilevel analyses to quantify the eco-epidemiological causation of physical unintentional injuries to children aged 16 years and younger. We conducted and reported the review in accordance with the PRISMA guidelines.

We included etiological studies of causal risk factors for unintentional traumatic injuries to children aged 0 to 16 years. Methodological inclusion criteria were as follows: Epidemiological studies quantifying the relationship between risk factors (at various levels) and injury occurrence in the individual; Studies that recognized individual exposure and at least 1 higher level of exposure with units at lower levels or microunits (e.g., individuals) nested within units at higher levels or macrounits (e.g., areas or neighborhoods); Injury outcomes (dependent variable) examined at the individual level; and Central analytic techniques belonging to the following categories: multilevel models, hierarchical models, random effects models, random coefficient models, covariance components models, variance components models, and mixed models. We combined criteria from the checklist described by the Cochrane Effective Practice and Organization of Care Review Group with factors in the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement, and we used several quality assessment items from other injury-related systematic reviews to create a quality assessment checklist for this review.

Two authors independently extracted data and selected analysis features for the included studies by using preformatted tables. They extracted information as reported in the articles. We determined statistical significance of estimates and effects by using the conventional threshold, P < .05. Any differences in the information extracted were resolved by discussion between authors and by specifically rereading and rechecking the facts as reported in the relevant articles. We tabulated results from the final multilevel model(s) in each of the included articles with key aspects summarized in text. Interpretations of the results and identification of key issues raised by the collated material are reported in the Discussion section of this article.

We identified 11,967 articles from the electronic search with only 14 being included in the review after a detailed screening and selection process. Nine of the 14 studies identified significant fixed effects at both the area and individual levels. The area-level variables most consistently associated with child injury rates related to poverty, education, employment, and access to services. There was some evidence that injury rates were lower in areas scoring well on area-level summary measures of neighborhood safety. There was marked variation in the methods used and in the mapping of measured variables onto the conceptual model of ecological causation. AUTHOR CONCLUSIONS: These results help establish the scope for the public policy approach to injury prevention. More consistent reporting of multilevel study results would aid future interpretation and translation of such findings.