Epilepsy and risk of suicide: a population-based case-control study

Background Studies have linked epilepsy with an increased suicide risk, but the association might be modified by psychiatric, demographic, and socioeconomic factors. Methods Suicide cases were identified in the Cause of Death Register in Denmark from 1981 to 1997. Up to 20 controls, matched by sex, birth year, and calendar date, were assigned to each suicide case. Findings We identified 21169 cases of suicide and 423 128 controls. 492 (2 center dot 32%) individuals who committed suicide had epilepsy compared with 3140 (0 center dot 74%) controls, corresponding to a three times higher risk (rate ratio [RR] 3 center dot 17 [95% CI 2 center dot 88-3 center dot 50]; p<0 center dot 0001). The RR remained high after excluding those with a history of psychiatric disease and adjusting for socioeconomic factors (1 center dot 99, 1 center dot 71-2 center dot 32; p<0 center dot 0001). The highest risk of suicide was identified in patients with epilepsy and comorbid psychiatric disease, even after adjusting for socioeconomic factors (13 center dot 7, 11 center dot 8-16 center dot 0; p<0 center dot 0001). In individuals with epilepsy, the highest risk of suicide was found during the first half year after diagnosis was made (5 center dot 35, 3.43-8 center dot 33; p<0 center dot 0001), and was especially high in those with a history of comorbid psychiatric disease (29 center dot 2, 16 center dot 4-51 center dot 9; p<0 center dot 0001). Interpretation Individuals with epilepsy have a higher risk of suicide, even if coexisting psychiatric disease, demographic differences, and socioeconomic factors are taken into account. Our study identifies people with newly diagnosed epilepsy as a vulnerable group that require special attention.