Relationship between physical conditions and attempted or completed suicide in more than 9,300 individuals from the United Kingdom: a case-control study

Aims: The present study of 9,352 adults from the United Kingdom aimed to analyze associations between physical conditions and attempted or completed suicide. Methods: This case-control study included patients aged 16-90 years with a first attempted or completed suicide who were followed in general practices in the United Kingdom between January 2008 and December 2017 (index date). Individuals who had not attempted or completed suicide were matched (1:1) to those who had attempted or completed suicide by sex, age, index year, index month, and practice. Variables included sex, age, index year, index month, and all physical and psychiatric conditions diagnosed in more than 1% of patients who had attempted or completed suicide in the year prior to the index date. A multivariable logistic regression analysis was performed to assess possible associations. Results: The case-control study included 4,676 patients who had and 4,676 patients who had not attempted or completed suicide. After (1:1) matching, 52.1% of the patients were women and the mean (standard deviation) age was 33.6 (15.1) years. After adjusting for psychiatric conditions, we found that three past-year physical conditions were significantly associated with attempted or completed suicide. These conditions were unspecified injuries to the head (odds ratio [OR]=4.26, 95% confidence interval [CI]=2.27-8.00), sleep disorders (OR=1.60, 95% CI=1.09-2.32), and epilepsy (OR=1.57, 95% CI=1.04-2.39). Conclusions: Head injuries, sleep disorders, and epilepsy were associated with attempted or completed suicide. Further research is needed to gain a better understanding of the mechanisms underlying these relationships.