Suicide and Self-Harm in Intellectual Disability: A Systematic Review and Meta-Analysis.

Background: Individuals with intellectual disabilities (ID) are disproportionately exposed to several risk factors for suicidality. However, no meta-analysis has yet quantified the relative risk of suicide and self-harm, including suicide attempts, within this population. The aim of this project was to bring together and synthesise the research on suicidality among individuals with ID.

Methods: A systematic review and meta-analysis was carried out. Medline, Embase, Web of Science and PsycInfo were searched from inception through 4 August 2025. Observational studies with a quantitative design, evaluating the relative risk of suicide or self-harm, including suicide attempts, in individuals with and without ID, were included. Risk of bias was assessed using a shortened version of the Risk Of Bias In Non-randomized Studies-of Exposure (ROBINS-E) checklist. A random effects model was used to synthesise the results.

Results: Eleven primary studies were included in the review (n = 241 438). The level of ID severity was only presented in two articles. Compared to the general population, the pooled relative risk for death by suicide was 0.54 (95% CI 0.33 to 0.89, k = 6, I² = 77%) and the relative risk for self-harm was 3.16, (95% CI 2.3 to 4.35, k = 6, I² = 89%).

Conclusion: The findings suggest that individuals with ID have an elevated risk of self-harm but a lower risk of dying by suicide compared to the general population. However, these results should be interpreted with caution due to the limited number of primary studies and substantial between-study heterogeneity. Further, separate analyses of mild versus moderate-to-profound ID are warranted.