title: Occupational physical demand and risk of hip fracture in older women.
abstract: OBJECTIVE
  Hip fractures are leading causes of disability, morbidity and mortality among older women. Since physical activity helps maintain physical functioning and bone mineral density, occupational physical demand may influence fracture risk. This study investigates the association of occupational physical demand with hip fracture incidence among women.
  
  
  METHODS
  The Women's Health Initiative Observational Study is a multiethnic cohort of 93,676 postmenopausal women, 50-79 years of age at enrolment, enrolled from 1994 to 1998 at 40 geographically diverse clinical centres throughout the USA. Outcomes including hip fractures were assessed annually and up to 3 jobs held since age 18 years were reported by each woman. Occupational physical demand levels were assigned for each job through linkage of occupational titles with Standard Occupational Codes and the Occupational Information Network. Average, cumulative and peak physical demand scores both before and after menopause and throughout women's work life were estimated.
  
  
  RESULTS
  Women were followed through 2010 for an average of 11.5 years; 1834 hip fractures occurred during this time. We did not observe an overall association of occupational physical demand with subsequent risk of hip fracture after adjusting for age, race/ethnicity, birth region and education.
  
  
  CONCLUSIONS
  Previous research on occupations and hip fracture risk in women is inconclusive. This study was able to take critical risk periods into account and control for confounding factors in a large cohort of older women to show that overall occupational physical demand neither increases nor decreases risk of hip fracture later in life.
authors.affiliation: Department of Epidemiology and Biostatistics, Drexel University, School of Public Health, Philadelphia, Pennsylvania, USA.
authors.forename: Aimee J
authors.initials: AJ
authors.lastname: Palumbo
authors.affiliation: Department of Epidemiology and Biostatistics, Drexel University, School of Public Health, Philadelphia, Pennsylvania, USA.
authors.forename: Yvonne L
authors.initials: YL
authors.lastname: Michael
authors.affiliation: Department of Epidemiology and Biostatistics, Drexel University, School of Public Health, Philadelphia, Pennsylvania, USA Department of Environmental and Occupational Health, Drexel University, School of Public Health, Philadelphia, Pennsylvania, USA.
authors.forename: Igor
authors.initials: I
authors.lastname: Burstyn
authors.affiliation: Department of Epidemiology and Biostatistics, Drexel University, School of Public Health, Philadelphia, Pennsylvania, USA.
authors.forename: Brian K
authors.initials: BK
authors.lastname: Lee
authors.affiliation: Department of Epidemiology, University of Iowa, Iowa City, Iowa, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Wallace
mesh_terms: D000368:Aged; D015519:Bone Density; D015331:Cohort Studies; D005260:Female; D006615:Hip; D006620:Hip Fractures / Q000209:etiology; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009043:Motor Activity; D016273:Occupational Exposure; D009790:Occupations; D017698:Postmenopause; D012307:Risk Factors; D014481:United States; D014937:Work