title: Leptospirosis and Depression: A Nationwide Cohort Analysis.
abstract: OBJECTIVE
  We conducted a retrospective cohort study to investigate whether leptospirosis is a risk factor for depression.
  
  
  METHODS
  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.
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei City, Taiwan.|Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei City, Taiwan.
authors.forename: Chun-Hsiang
authors.initials: CH
authors.lastname: Chiu
authors.affiliation: Department of Family Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei City, Taiwan.
authors.forename: Ying-Chuan
authors.initials: YC
authors.lastname: Wang
authors.affiliation: Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan.|College of Medicine, China Medical University, Taichung, Taiwan.
authors.forename: Cheng-Li
authors.initials: CL
authors.lastname: Lin
authors.affiliation: Department of Emergency Medicine, Taichung Tzu Chi Hospital, Taichung, Taiwan.
authors.forename: Feng-You
authors.initials: FY
authors.lastname: Lee
authors.affiliation: Graduate Institute of Clinical Medicine Science and School of Medicine, College of Medicine, China Medical University, No. 2, Yuh-Deh Rd, Taichung 404, Taiwan. d10040@mail.cmuh.org.tw.|Graduate Institute of Clinical Medical Science and School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan.|Department of Nuclear Medicine and PET Center, China Medical University Hospital, Taichung, Taiwan.|Department of Bioinformatics and Medical Engineering, Asia University, Taichung, Taiwan.
authors.forename: Chia-Hung
authors.initials: CH
authors.lastname: Kao
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D016208:Databases, Factual; D003866:Depressive Disorder / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007922:Leptospirosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology