title: Epidemiologic determinants of endometriosis: a hospital-based case-control study.
abstract: OBJECTIVE
  Risk factors for endometriosis were identified through data obtained from a case-control study at Brigham and Women's Hospital in Boston, Massachusetts.
  
  
  METHODS
  Cases were 50 women with infertility-associated endometriosis. The primary control group consisted of 89 fertile women without endometriosis, and an alternate control group consisted of 47 infertile women without endometriosis.
  
  
  RESULTS
  The risk of endometriosis was positively associated with height (OR), 2.8 per 10 cam increase; 95% confidence interval (CI), 1.4-5.6) and inversely associated with weight (OR, 0.7 per 10 kg increase; 95% CI, 0.5-1.0) and body mass index (OR, 0.7 per 5 kg/m2 increase; 95% CI, 0.4-1.1). We observed an inverse association with exercise (OR, 0.6; 95% CI, 0.3-1.5), but the effect was limited to women who exercised > or = 4 hours per week (OR, 0.4; 95% CI, 0.2-1.2). Endometriosis was not associated with either smoking or alcohol consumption.
  
  
  CONCLUSIONS
  Our findings suggest that the fertility status of controls can strongly influence associations seen with menstrual characteristics. This study is one of few to address the issue of control selection for a case-control study of endometriosis. Specifically, potential problems encountered using fertile and infertile control women are examined and discussed.
authors.affiliation: Obstetrics and Gynecology Epidemiology Center, Brigham and Women's Hospital, Boston, MA 02115, USA.
authors.forename: L B
authors.initials: LB
authors.lastname: Signorello
authors.forename: B L
authors.initials: BL
authors.lastname: Harlow
authors.forename: D W
authors.initials: DW
authors.lastname: Cramer
authors.forename: D
authors.initials: D
authors.lastname: Spiegelman
authors.forename: J A
authors.initials: JA
authors.lastname: Hill
mesh_terms: D000328:Adult; D000437:Alcoholism; D015992:Body Mass Index; D016022:Case-Control Studies; D016001:Confidence Intervals; D004715:Endometriosis / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D015994:Incidence; D007247:Infertility, Female / Q000453:epidemiology* / Q000209:etiology; D008019:Life Style; D008404:Massachusetts / Q000453:epidemiology; D012307:Risk Factors; D012907:Smoking