The impact of multimorbidity on suicidal behaviour: A systematic review and meta-analysis

Multimorbidity, the co-occurrence of multiple health conditions, is increasingly recognised as a significant public health concern. While the association between multimorbidity and suicidal thoughts is well-documented, its relationship with suicidal behaviour remains underexplored. This study aims to quantify the association between multimorbidity and both suicide attempts and suicide mortality.

We searched Medline, PsycINFO, and Scopus databases for studies published from January 1990 up to July 2024. We applied prespecified eligibility criteria to select studies for inclusion. To assess the risk of bias, we used the Mixed Methods Appraisal Tool. We conducted meta-analyses using random-effects models and assessed heterogeneity with Cochran's Q and I² statistics. We evaluated publication bias using funnel plots and Egger's test. Sub-group analysis was conducted incorporating potential moderator variables.

Out of 2202 identified records, 38 studies were included in the analysis. Participants with multimorbidity were over five times more likely to attempt suicide compared to those without multimorbidity (pooled odds ratio [OR] = 5.31; 95 % confidence interval [CI] = 3.98, 7.09; I² = 94.9 %). Multimorbidity was associated with an 83 % increased likelihood of suicide mortality (pooled OR = 1.83; 95 % CI = 1.21, 2.77; I² = 99.9 %). Mental multimorbidity was associated with the highest odds of suicide attempts (OR = 6.96; 95 % CI = 4.94, 9.81; I² = 81.8 %), with higher odds also observed in studies with single disease comparator (OR = 6.16; 95 % CI = 3.68, 10.31; I² = 95.5 %), and across both high income and low-middle income regions. For suicide mortality, significant associations were found in studies assessing physical-mental multimorbidity (OR = 2.32; 95 % CI = 1.14, 4.71; I² = 99.8 %), studies from Europe/USA and Asia, and those using a mixed comparator group, with additional significant effects noted by study design, publication year, covariate adjustment, and risk of bias.

Multimorbidity significantly increases the risk of both suicide attempts and suicide mortality. We recommend enhanced suicide risk assessment among patients with multiple chronic conditions, especially when mental health diagnoses are present.