Predictors of injury mortality in early childhood

Objective. To study the association between maternal/infant characteristics and mortality from injury for children 0 through 4 years of age. Design. Historical cohort. Setting. State of Tennessee. Participants. Children 0 through 4 years of age at any time between January 1, 1985 and December 31, 1994. We linked birth certificates and US census data to obtain information on maternal age, race, education, neighborhood income, parity, use of prenatal care, residence location, infant's gender, and gestational age. Main Outcome Measures. The outcome was death from injury, as determined from linked death certificates. The incidence density rates for each stratum (defined by maternal/child characteristics) were calculated by dividing the number of injury deaths by child years in the stratum. We used multivariate analysis to assess the independent contribution of each characteristic to risk of injury death. Results. There were 1 035 504 children 0 through 4 years of age who contributed 3 414 436 child years. There were 803 deaths from injury, ie, 23.5 deaths per 100 000 child years. In the multivariate analysis, children had at least a 50% increased risk of injury mortality if they were born to a mother who had less than a high school education (relative risk [RR] = 2.88; 95% confidence interval [CI]: 1.92-4.34) compared with a college education, was <20 years of age (RR = 2.42; 95% CI: 1.76-3.31) compared with >30 years, or had >2 other children (RR = 2.97; 95% CI: 2.29-3.85) compared with no other children. Neither race nor income was significantly associated with childhood injury mortality in the multivariate analysis. Classification of children by maternal education, age, and parity defined a pronounced risk gradient in which highrisk children had an injury mortality rate >15 times that of low-risk children. The steep risk gradient was present for both infants (24-fold increase for high-risk children) and children 1 through 4 years of age (13-fold increase for high-risk children). If the injury mortality rate for all children were equal to that of the low-risk group, 614/803 (76.3%) of injury deaths would not have occurred. Conclusions. For young children, maternal education, age, and parity are strongly and independently associated with injury mortality. These factors define a steep gradient of risk, suggesting that many injury deaths could be prevented.