Sociodemographic Factors Identify US Infants at High Risk of Injury Mortality

Abstract

Objectives. To identify sociodemographic predictors of infant injury mortality and to compare trends in injury mortality rates for high- and low-risk US infants from 1985 to 1991. Design. Historical cohort. Setting/Study Participants. The National Center for Health Statistics linked US infants (<1 year) born from 1985 to 1991 with death certificates. Main Outcome Measures. Multivariate regression was used to identify sociodemographic factors associated with injury mortality. The adjusted relative risks (RRs) of maternal age, education, marital status, number of other children, and infant birth weight were used to categorize infants into risk groups. We compared trends in injury rates for the highest and lowest risk groups. Results. There were 5963 injury deaths and 18.6 million infant years or 32.1 injury deaths per 100 000 infant years. Highest risk infants were born to mothers who were younger than 20 years compared with older than 30 years (RR, 3.25; 95% CI, 2.92–3.63), had less than a high school education compared with a college education (RR, 2.22; 95% CI, 1.95–2.53), had more than 2 other children compared with no other children (RR, 3.15; 95% CI, 2.88–3.45), were unmarried (RR, 1.67; 95% CI, 1.57–1.78), or had birth weights ≤1500 g compared with >2500 g (RR, 3.36; 95% CI, 2.94–3.84). Infants in the highest risk group (21.0% of the population) had a >10-fold increased risk of injury mortality compared with the lowest risk group (18.1% of the population) and there was no evidence that this disparity was narrowing. Conclusions. Sociodemographic predictors of infant injury mortality include maternal age, education, number of other children, marital status, and infant birth weight. Based on these factors, 1 in 5 infants in the United States can be identified at birth as having a >10-fold increased risk of injury mortality compared with infants in lowest risk group. Programs to reduce injuries in these high-risk groups are urgently needed.