Suicide risk of chronic diseases and comorbidities: A Korean case-control study

Objectives: Chronic diseases including mental disorders have been associated with suicide. This study broadens the approach by incorporating a comprehensive list of chronic diseases and a context of comorbidities and explored their associations with suicide. Methods: Data-linkage between death registry and Korean National Health Insurance data was conducted. Suicide cases (n = 64,099) between 2009 and 2013 were 1:4 matched for gender and age to an alive control (n = 256,396). A total of 92 individual diseases of 9 broad categories were identified from insurance claims data. Conditional logistic regression was applied to assess the associations, adjusting for mental and behavioral disorders and socioeconomic status. Results: Suicide cases frequently experienced chronic diseases (90.0 %) and comorbidities (74.6 %). Chronic diseases greatly increased suicide risk and, among these, mental and behavioral disorders showed the highest suicide risk (OR = 7.53, 95 % CI = 7.32–7.74) followed by cardiovascular (OR = 3.36, 95 % CI = 3.26–3.47). For individual diseases, gastritis and duodenitis were most prevalent (68.1 %) among suicide cases but depressive disorder showed the highest risk (OR = 4.95, 95 % CI = 4.79–5.12). Suicide risk was strong in comorbid status sometimes comparable to odds for mental and behavioral disorder alone (e.g., OR for cardiovascular and eye vision-related diseases = 4.01, 95 % CI = 3.86–4.17). Limitations: Differentiation of comorbidity was limited to pairs between major disease categories, neglecting the heterogeneity within categories. Conclusion: Chronic diseases, in particular comorbidity, showed strong associations with suicide. This suggests that those with comorbidities feel that they are pushed to the extreme line, supporting comprehensive interventions for them to address wider reasons including psychological and social problems, besides medical problems.