Leptospirosis and Depression: A Nationwide Cohort Analysis

Objective: We conducted a retrospective cohort study to investigate whether leptospirosis is a risk factor for depression.

Method: From the Taiwan National Health Insurance Research Database between 2000 and 2010, patients with leptospirosis (ICD-9 code 100) who did not have a history of depression (ICD-9-CM codes 296.2, 296.3, 300.4, and 311) before the index date were enrolled (leptospirosis cohort). For each patient with leptospirosis, 1 control without a history of leptospirosis and depression was randomly selected (nonleptospirosis cohort). Cox proportional hazards regression models were used to analyze the risk of depression according to sex, age, and comorbidities.

Results: In the leptospirosis and nonleptospirosis cohorts, we observed 34 patients with depression, with the incidence rate of 2.87 per 1,000 person-years, and 25 patients with depression, with the incidence rate of 1.93 per 1,000 person-years, respectively, yielding a crude hazard ratio (HR) of 1.49 (95% confidence interval [CI], 1.25-1.77) and an adjusted HR (aHR) of 1.58 (95% CI, 1.34-1.88). Compared with the nonleptospirosis cohort, the leptospirosis cohort had a risk of depression stratified by sex, age, and comorbidity that was higher in female patients (aHR = 2.08; 95% CI, 1.54-2.80), patients younger than 49 years old (aHR = 3.19; 95% CI, 2.39-4.27), and patients without comorbidity (aHR = 2.14; 95% CI, 1.68-2.71). The risk of depression was higher in women than in men (aHR = 1.90; 95% CI, 1.61-2.25) and in patients with comorbidities, namely hyperlipidemia (aHR = 1.80; 95% CI, 1.40-2.31), coronary artery disease (aHR = 2.47; 95% CI, 1.96-3.12), stroke (aHR = 1.77; 95% CI, 1.39-2.24), and septicemia (aHR = 2.06; 95% CI, 1.64-2.58).

Conclusions: Patients with leptospirosis have a 1.58-fold higher risk of depression than that in the general population. Physicians should be alert to the emotional condition and depression symptoms of people who had been suffering from leptospirosis.