title: Association between sexually transmitted disease and church membership. A retrospective cohort study of two Danish religious minorities.
abstract: OBJECTIVE
  Studies comprising Danish Seventh-day Adventists (SDAs) and Danish Baptists found that members have a lower risk of chronic diseases including cancer. Explanations have pointed to differences in lifestyle, but detailed aetiology has only been sparsely examined. Our objective was to investigate the incidence of sexually transmitted diseases (STDs) among Danish SDAs and Baptists as a proxy for cancers related to sexual behaviour.
  
  
  METHODS
  We followed the Danish Cohort of Religious Societies from 1977 to 2009, and linked it with national registers of all inpatient and outpatient care contacts using the National Patient Register. We compared the incidence of syphilis, gonorrhoea and chlamydia among members of the cohort with the general population.
  
  
  RESULTS
  The cohort comprised 3119 SDA females, 1856 SDA males, 2056 Baptist females and 1467 Baptist males. For the entire cohort, we expected a total of 32.4 events of STD, and observed only 9. Female SDAs and Baptists aged 20-39 years had significant lower incidence of chlamydia (both p<0.001). Male SDAs and Baptists aged 20-39 years also had significant lower incidence of chlamydia (p<0.01 and p<0.05, respectively). No SDA members were diagnosed with gonorrhoea, when 3.4 events were expected, which, according to Hanley's 'rule of three', is a significant difference. No SDA or Baptist was diagnosed with syphilis.
  
  
  CONCLUSIONS
  The cohort shows significant lower incidence of STD, most likely including human papillomavirus, which may partly explain the lower incidence of cancers of the cervix, rectum, anus, head and neck.
authors.affiliation: Research Unit of General Practice, University of Southern Denmark, Odense, Denmark.
authors.forename: Alex Kappel
authors.initials: AK
authors.lastname: Kørup
authors.affiliation: National Institute of Public Health, Copenhagen, Denmark.
authors.forename: Lau Caspar
authors.initials: LC
authors.lastname: Thygesen
authors.affiliation: Research Unit of General Practice, University of Southern Denmark, Odense, Denmark.
authors.forename: René dePont
authors.initials: Rd
authors.lastname: Christensen
authors.affiliation: Department of Oncology Clinic, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Christoffer
authors.initials: C
authors.lastname: Johansen
authors.affiliation: Research Unit of General Practice, University of Southern Denmark, Odense, Denmark.
authors.forename: Jens
authors.initials: J
authors.lastname: Søndergaard
authors.affiliation: Research Unit of General Practice, University of Southern Denmark, Odense, Denmark.
authors.forename: Niels Christian
authors.initials: NC
authors.lastname: Hvidt
mesh_terms: D000328:Adult; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008019:Life Style; D008297:Male; D033303:Protestantism / Q000523:psychology*; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D012725:Sexual Behavior / Q000523:psychology / Q000706:statistics & numerical data*; D012749:Sexually Transmitted Diseases / Q000453:epidemiology* / Q000523:psychology; D012931:Social Environment; D014565:Urogenital Neoplasms / Q000453:epidemiology* / Q000523:psychology
keywords: SOCIAL MEDICINE; STD; chlamydia; gonorrhea; religion; syphilis