Background: Although the clinical importance of non-suicidal self-injury (NSSI) has received increasing recognition, relatively little is known about its epidemiology. The objective of this study was to estimate the lifetime prevalence of NSSI in adults and its association with sociodemographic characteristics, psychiatric disorders, and lifetime treatment for NSSI.

Methods: A nationally representative face-to-face survey was conducted with 7192 adults aged ≥18 years in England. Respondents were interviewed about engagement in NSSI, psychiatric illness, suicidal thoughts and behavior, and treatment history for this behavior.

Results: The estimated lifetime prevalence rate of NSSI was 4.86%. Younger age, growing up without biological parents in the household, being unmarried, and impoverished backgrounds were associated with NSSI. The majority of respondents with lifetime NSSI (63.82%) had at least one current psychiatric disorder. Most psychiatric conditions were associated with greater odds of lifetime NSSI in multivariate models. NSSI was strongly associated with suicidal ideation and suicide attempts, respectively, even after accounting for psychiatric disorders and sociodemographic covariates. A substantial proportion of respondents with NSSI history (30.92%) have engaged in medically severe self-harm, as indexed by requiring medical attention for this behavior. The majority of respondents with NSSI (56.20%) had not received psychiatric care for this behavior.

Conclusions: NSSI is prevalent in the general population and associated with considerable psychiatric comorbidity. A high rate of unmet treatment needs is evident among those with this behavior. Those at the greatest lifetime risk for NSSI may also be particularly limited in their resources to cope with this behavior.