Suicidality 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 synthesize 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 May 24, 2024. Observational studies with a quantitative design examining ID as the exposure and reporting relative risk estimates for suicide or self-harm, including suicide attempts, 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 synthesize 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 intellectual disabilities 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.