title: Association of systemic lupus erythematosus and sleep disorders: a nationwide population-based cohort study.
abstract: OBJECTIVE
  Using a population-based cohort study, we investigated whether sleep disorders (SDs) increase the risk of systemic lupus erythematosus (SLE).
  
  
  METHODS
  We identified patients with SDs and a control cohort from 1998-2001 by using the Taiwan Longitudinal Health Insurance Database 2000. Two controls for each patient with an SD were selected and randomly frequency-matched according to age, gender, and index year. The follow-up person-years were estimated for the patients from the index date to SLE diagnosis, loss to follow-up, or the end of 31 December 2011. We used the Cox proportional hazards models to evaluate how SDs influence the risk of SLE after adjustments for demographic factors and comorbidities.
  
  
  RESULTS
  A total of 144,396 subjects (48,132 SD cases and 96,264 controls) were followed for 1,477,055 person-years. The patients with SDs displayed higher incidence density rate of developing SLE than did the controls (1.03 vs. 0.46 per 10,000 person-years). After adjustment for covariates, the patients with SDs exhibited a 2.20-fold higher adjusted hazard ratio (aHR) of developing SLE than the controls (95% confidence interval (CI) = 1.44-3.36). Women exhibited a greater prevalence of SDs and SLE compared to men. Patients with SDs aged 49 years and younger exhibited a significantly increased risk of SLE compared to the controls (aHR=2.30, 95% CI = 1.33-3.98). Patients with SDs living in urban areas exhibited a significantly increased risk of SLE.
  
  
  CONCLUSIONS
  This large population-based cohort study revealed that SDs increase the risk of SLE development.
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: W S
authors.initials: WS
authors.lastname: Chung
authors.affiliation: Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan College of Medicine, China Medical University, Taichung, Taiwan.
authors.forename: C L
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 d10040@mail.cmuh.org.tw.
authors.forename: C H
authors.initials: CH
authors.lastname: Kao
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D015897:Comorbidity; D016208:Databases, Factual; D005260:Female; D005500:Follow-Up Studies; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008137:Longitudinal Studies; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D016016:Proportional Hazards Models; D012307:Risk Factors; D017678:Sex Distribution; D012893:Sleep Wake Disorders / Q000175:diagnosis / Q000453:epidemiology*; D013624:Taiwan / Q000453:epidemiology; D013997:Time Factors; D014504:Urban Health
keywords: Sleep disorders; cohort study; systemic lupus erythematosus