Eczema and subsequent suicide: a matched case-control study

Objective To assess the association of eczema with a patient's subsequent risk of death from suicide. We hypothesised that persistent eczema would be associated with an increased risk for death from suicide. Design Double matched case-control study. Setting General population of Ontario, Canada. Participants Patients 15-55 years old. We identified cases of suicide from coroners' reports between 1 January 1994 and 31 December 2014 and matched 1:2 with alive controls based on age, sex and socioeconomic status. Exposure The primary predictor was a history of persistent eczema, defined as five or more physician visits for the diagnosis over the preceding 5years. Main outcome and measure Logistic regression to estimate the association between eczema and death from suicide. Results We identified 18441 cases of suicide matched to 36882 controls over the 21-year accrual period. Persistent eczema occurred in 174 (0.94%) suicide cases and 285 (0.77%) controls yielding a 22% increased risk of suicide associated with persistent eczema (OR 1.22, 95% CI 1.01 to 1.48, p=0.037). In mediation analyses, this association was largely explained through major suicide risk factors. Two-thirds of patients with eczema who died from suicide had visited a physician in the month before their death and one in eight had visited for eczema in the month before their death. Among patients who died by suicide, jumping and poisoning were relatively more frequent mechanisms among patients with eczema. Conclusions Patients with persistent eczema have a modestly increased subsequent risk of death from suicide, but this is not independent of overall mental health and the absolute risk is low. Physicians caring for these patients have opportunities to intervene for suicide prevention.