Sex Differences in the Global Prevalence of Nonsuicidal Self-Injury in Adolescents: A Meta-Analysis

Abstract

Importance: Nonsuicidal self-injury (NSSI) is a strong predictor of suicide attempts. The prevalence of NSSI has been increasing among female adolescents in North America and Europe, but less is known about trends in other geographical regions.

Objective: To examine sex differences in the prevalence of NSSI among adolescents within and between geographical regions.

Data sources: MEDLINE and PsycINFO were searched using the keywords adolescents, self-injury, sex factors, and synonyms for articles published in English between January 1, 2000, and May 10, 2022.

Study selection: Studies were included if they presented original data (any study design), included adolescents aged 10 to 19 years, reported results stratified by sex, and explicitly defined self-injury as behaviors occurring without suicidal intent.

Data extraction and synthesis: This meta-analysis was registered with PROSPERO and conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Articles were assessed for quality by 2 independent coders (F.M. and J.A.). A random-effects model was used to calculate prevalence. Data were analyzed from July 2022 to April 2023.

Main outcomes and measures: The prevalence of NSSI in male and female adolescents within and between regions was the main outcome. Odds ratios (OR) with 95% CIs were calculated for community samples.

Results: Eight hundred and two studies were screened, and 38 were included (266 491 participants). Across 17 countries, the pooled prevalence of NSSI was 17.7% (female:male OR, 1.60; 95% CI, 1.29-1.98). NSSI was twice as prevalent among female adolescents compared with male adolescents in North America (OR, 2.49; 95% CI, 2.16-2.86) and Europe (OR, 2.08; 95% CI, 1.69-2.58), but not in Asia (OR, 1.00; 95% CI, 0.71-1.41).

Conclusions and relevance: In this meta-analysis of sex differences in global prevalence of NSSI, the female predominance of NSSI observed among adolescents in North America and Europe aligned with rising rates of suicide in these populations. The comparable prevalence of NSSI among male and female adolescents in Asia also aligned with the lower male-to-female suicide ratio compared with other countries. More research is needed to characterize regional (and potentially cultural) sex differences among adolescents with NSSI to prevent and treat the behavior and to understand the possible interplay with corresponding regional trends in suicide.

Figure 1.. Flow Diagram of the Study Selection Process

^aEight hundred fifty-three from MEDLINE, 221 from APA PsycINFO. ^bExcluded due to limited relevance (eg, only reported on NSSI in individuals with 1 specific diagnosis or characteristic).

Figure 2.. Geographical Distribution of Included Community Samples, Separated by Continent

Number in box indicates No. of studies from each region. ^aTurkey is part of both Europe and Asia. For the purposes of this study, Turkey was included as a country in Asia.

Figure 3.. Forest Plot Depicting Odds Ratio (OR; Effect Size) for Nonsuicidal Self-Injury in Female Adolescents as Compared With Male Adolescents for All Included Community Studies

Total row indicates overall effect size with CI (bold) and prediction interval (interval within which future value will fall).

Figure 4.. Pooled Prevalence of Nonsuicidal Self-Injury (NSSI) by Gender and Region (Community Samples Only)

Error bars denote SE.