Prevalence and associated factors of non-suicidal self-injury among Chinese adults: a national, population-based cross-sectional study

Background: Non-suicidal self-injury (NSSI) is a major global public health issue, however, its prevalence and characteristics among Chinese adults remain poorly understood due to the absence of nationwide epidemiological data. This study aimed to assess the prevalence, frequency, requirement for treatment, and associated factors of NSSI in a nationally sample of community-dwelling Chinese adults. Methods: A population-based, cross-sectional survey was conducted in China from June to August 2024. Using a multistage, stratified, cluster-sampling method, a total of 25,047 Chinese Nationals aged 18 or older were included. Data on NSSI (including lifetime prevalence, past-year frequency, and requirement for treatment) and its sociodemographic and psychosocial correlates, were collected through structured questionnaires. Findings: After logical checks and quota sampling based on national population statistics, 25,047 participants were included in the final analysis. The estimated lifetime prevalence of NSSI was 4.1% (95% CI: 3.8%-4.3%). Past-year prevalence was 2.0% (95% CI: 1.8%-2.2%), while 1.4% (95% CI: 1.3%-1.6%) of participants reported NSSI episodes requiring medical treatment. Multivariate logistic regression analysis revealed a strong graded association between NSSI risk and both the severity of depressive symptoms (OR up to 7.02, 95% CI 5.75-8.57 for severe symptoms; P < 0.001) and the number of chronic physical conditions (OR up to 1.83, 95% CI 1.43-2.35 for ≥2 conditions; P < 0.001). Additional significant risk factors included younger age, female sex (OR = 1.38, 95% CI 1.19-1.60; P = 0.006), only-child status (OR = 1.23, 95% CI 1.06-1.43; P < 0.001), recent trauma (OR = 1.80, 95% CI 1.56-2.07; P < 0.001), smoking (OR = 1.97, 95% CI 1.66-2.35; P < 0.001), and obesity (OR = 1.42, 95% CI 1.02-1.99; P = 0.040). Interpretation: The substantial prevalence of NSSI among Chinese adults represents a serious public health challenge. These findings suggest that NSSI in the adult population deserves greater clinical attention and that future research should assess the value of incorporating self-harm screening into routine health assessments. Globally, these findings support the case for increased attention and research funding for understanding NSSI in LMICs. Funding: This study was supported by the Brain Science and Brain-like Intelligence Technology-National Science and Technology Major Project (2021ZD0200600).