Mortality in a cohort of 3.1 million children, adolescents and young adults.

backgroundMany youth deaths occur in the first year of life, from prematurity and anomalies. Detailing mortality after age 1 year may differentially guide preventive strategies in children, adolescents and young adults.

methodsA cohort study in Ontario, Canada comprised 3 139 698 children born from 1990 to 2016. Adjusted HR (aHR) for death between 1 and 24 years were generated, comparing demographic variables and parity.

resultsAfter a median of 13.7 years of follow-up, 6930 deaths occurred between ages 1 and 24 years (incidence rate 17.0 per 100 000 person-years), peaking at age 23 years (43.7 per 100 000). The aHR for death was higher among males than females (1.44, 95% CI 1.37 to 1.51), rural versus urban areas (1.48, 95% CI 1.39 to 1.58), lowest versus highest income areas (1.39, 95% CI 1.29 to 1.51) and at parity 1 (1.16, 95% CI 1.10 to 1.23), parity 2 (1.34, 95% CI 1.23 to 1.45), parity 3+ (1.96, 95% CI 1.74 to 2.21), each relative to a child without an older sibling. Among males, the proportion of deaths due to injury jumped from 30% before age 15 years to 65% thereafter, and in females, from 28% to 51%. Intentional self-harm/assault explained 11% of injury-related deaths among males before age 15 years, and 20% thereafter, with respective figures of 18% and 17% for females. Deaths outside of hospital increased with age, from 35% at age 1 year, to 66% at age 22 years.

conclusionThere is a heightened susceptibility of dying starting at age 15 years, especially among males, from injury, and arising outside of hospital.