title: Increased risk of acute coronary syndrome among leptospirosis patients: A nationwide cohort analysis.
abstract: BACKGROUND
  Studies on the association between leptospirosis and acute coronary syndrome (ACS) are lacking. Therefore, this study identifies the effects of leptospirosis on the risks of developing ACS with a nationwide retrospective cohort study.
  
  
  METHODS
  We identified adult patients aged ≥20 years who were newly diagnosed with leptospirosis. We also randomly selected a comparison cohort from the general population by using a propensity score matching method. We analyzed the risks of ACS by using Cox proportional hazard regression models.
  
  
  RESULTS
  Among the 23.74 million people in the cohort, 3690 patients with leptospirosis (68% men, mean age of 52.2 years) and 3690 controls were followed for 13,677 and 15,652 person-years, respectively. The overall incidence of ACS was higher in the leptospirosis cohort than in the nonleptospirosis cohort (4.68 vs 3.71 per 1000 person-years), with a hazard ratio (HR) of 1.69 (95% confidence interval [CI]=1.12-2.56). Men exhibited a 1.88-fold greater HR of ACS than women did (95% CI=1.20-2.94). The risk of developing ACS was highest for leptospirosis patients aged ≥65 years (HR=7, 51% CI=4.35-12.9) compared with patients aged ≤49 years.
  
  
  CONCLUSIONS
  Leptospirosis is not a previously identified risk factor for ACS. The findings of this nationwide retrospective cohort study indicate that leptospirosis may become an independent risk factor for ACS. Future research to investigate the mechanism is warranted.
authors.affiliation: Department of Internal Medicine, Taichung Hospital, Ministry of Health and Welfare, Taichung, Taiwan; Department of Health Services Administration, China Medical University, Taichung, Taiwan; Department of Healthcare Administration, Central Taiwan University of Science and Technology, Taichung, Taiwan.
authors.forename: Wei-Sheng
authors.initials: WS
authors.lastname: Chung
authors.affiliation: Department of Internal Medicine, Taichung Hospital, Ministry of Health and Welfare, Taichung, Taiwan.
authors.forename: Yung-Hua
authors.initials: YH
authors.lastname: Chu
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: 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. Electronic address: d10040@mail.cmuh.org.tw.
authors.forename: Chia-Hung
authors.initials: CH
authors.lastname: Kao
mesh_terms: D054058:Acute Coronary Syndrome / Q000453:epidemiology*; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007922:Leptospirosis / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D013624:Taiwan
keywords: Acute coronary syndrome (ACS); Leptospirosis; Nationwide cohort study