Age and Birth Cohort–Adjusted Rates of Suicide Mortality Among US Male and Female Youths Aged 10 to 19 Years From 1999 to 2017

Abstract

This cross-sectional study examines time trends and sex differences in the suicide mortality rate among US youths adjusted for birth cohort and age.

Key Points

Question

Does a measure of suicide mortality calculated by adjusting for chronological age and year of birth differ from unadjusted models?

Findings

In this multiyear cross-sectional study using data from the US Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research database, age and birth cohort–adjusted suicide mortality rates were estimated after controlling for a curved age effect and a V-shaped cohort effect that also differed by sex. The adjusted rates showed a more rapid increase and a smaller sex difference in the suicide mortality rates for US youths aged 10 to 19 years from 1999 to 2017.

Meaning

Age and birth cohort–adjusted suicide mortality rates may be an unbiased measure of the time trend and sex pattern in suicide among US youths and may be useful for informing evidence-based suicide prevention.

Abstract

Importance

Strategic planning to curb increasing suicide rate among US youths requires unbiased measures of suicide mortality, as the unadjusted suicide mortality rates conventionally used in describing time trends and sex patterns are confounded by the differences in chronological age and year of birth.

Objective

To measure time trends and sex differences in suicide mortality among US youths using age and birth cohort (age-cohort)–adjusted rates.

Design, Setting, and Participants

This population-based multiyear cross-sectional study of US youths aged 10 to 19 years was a secondary analysis of the suicide data for January 1, 1999, to December 31, 2017, derived from the Wide-Ranging Online Data for Epidemiologic Research, a database prepared by the US Centers for Disease Control and Prevention to promote research. Data analysis was conducted from May 24 to May 27, 2019.

Main Outcomes and Measures

Age-cohort–adjusted suicide mortality rates by year and sex were used as the main outcomes. These adjusted rates were calculated based on the period effect estimated with the age-period-cohort (APC) modeling method. Participants’ age, year of birth, and the year when suicide occurred were used as time-related risk factors.

Results

Age-cohort–adjusted suicide mortality rates were estimated successfully by year and by sex. The adjusted rates were obtained after controlling for a V-shaped cohort effect and a curved age effect that also differed by sex. The unadjusted suicide mortality rate for male youths increased from 7.4 per 100 000 in 1999 to 10.7 per 100 000 in 2017, while the adjusted rate increased from 4.9 per 100 000 in 1999 to 8.7 per 100 000 in 2017. The unadjusted suicide mortality rates for female youths were 1.6 per 100 000 in 1999 and 3.5 per 100 000 in 2017, while the adjusted rates were 1.7 per 100 000 in 1999 and 4.2 per 100 000 in 2017.

Conclusions and Relevance

Findings of this study indicate a more rapid increase and smaller male-female difference in suicide rates among US youths since 1999 than those shown by the unadjusted suicide mortality rates. The adjusted rates provide unbiased data that are needed for evidence-based decision-making and strategies to curb the increasing suicide rates among US youths.