title: Occupational risk factors for endometriosis in a cohort of flight attendants.
abstract: OBJECTIVE
  This study aimed to (i) compare odds of endometriosis in a cohort of flight attendants against a comparison group of teachers and (ii) investigate occupational risk factors for endometriosis among flight attendants.
  
  
  METHODS
  We included 1945 flight attendants and 236 teachers aged 18-45 years. Laparoscopically confirmed endometriosis was self-reported via telephone interview, and flight records were retrieved from airlines to obtain work schedules and assess exposures for flight attendants. We used proportional odds regression to estimate adjusted odds ratios (OR adj) and 95% confidence intervals (95% CI) for associations between exposures and endometriosis, adjusting for potential confounders.
  
  
  RESULTS
  Flight attendants and teachers were equally likely to report endometriosis (OR adj1.0, 95% CI 0.5-2.2). Among flight attendants, there were no clear trends between estimated cosmic radiation, circadian disruption, or ergonomic exposures and endometriosis. Greater number of flight segments (non-stop flights between two cities) per year was associated with endometriosis (OR adj2.2, 1.1-4.2 for highest versus lowest quartile, P trend= 0.02) but block hours (taxi plus flight time) per year was not (OR adj1.2, 95% CI 0.6-2.2 for highest versus lowest quartile, P trend=0.38).
  
  
  CONCLUSIONS
  Flight attendants were no more likely than teachers to report endometriosis. Odds of endometriosis increased with number of flight segments flown per year. This suggests that some aspect of work scheduling is associated with increased risk of endometriosis, or endometriosis symptoms might affect how flight attendants schedule their flights.
authors.affiliation: National Institute for Occupational Safety and Health, 1090 Tusculum Ave MS R-15, Cincinnati, OH, 45226, USA. cyjohnson@cdc.gov.
authors.forename: Candice Y
authors.initials: CY
authors.lastname: Johnson
authors.forename: Barbara
authors.initials: B
authors.lastname: Grajewski
authors.forename: Christina C
authors.initials: CC
authors.lastname: Lawson
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Whelan
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Bertke
authors.forename: Chih-Yu
authors.initials: CY
authors.lastname: Tseng
mesh_terms: D000293:Adolescent; D000328:Adult; D000337:Aerospace Medicine; D021081:Chronobiology Disorders / Q000150:complications; D003359:Cosmic Radiation / Q000009:adverse effects*; D004715:Endometriosis / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects*; D016017:Odds Ratio; D012189:Retrospective Studies; D012307:Risk Factors; D000070777:School Teachers; D057566:Self Report; D011795:Surveys and Questionnaires; D055815:Young Adult