title: Changes in the Relationships Between Body Mass Index and Health Outcomes Across Middle Age and Older Adulthood.
abstract: OBJECTIVE
  To examine patterns of the incidence of diabetes, hypertension, and mortality by single units of body mass index (BMI) and 5-year age groups using longitudinal data from middle-aged and older women.
  
  
  METHODS
  Middle-aged (born between 1946 and 1951; N = 13,715) and older (born between 1921 and 1926; N = 12,432) participants in the Australian Longitudinal Study on Women's Health completed surveys in 1996 and at approximately 3-year intervals thereafter until 2011. Proportions of women with diabetes, hypertension, and mortality over 3-year intervals were estimated for each unit of BMI and 5-year age group (45 to < 50, 50 to < 55, 55 to < 60, 70 to < 75, 75 to < 80, and 80 to < 85 years) using generalized additive modeling with adjustment for time-varying covariates.
  
  
  RESULTS
  Three-year incidence of diabetes (1.2%-3.6%), hypertension (5.2%-17.8%), and death (0.4%-9.5%) increased with age. For both diabetes and hypertension, the associations with BMI were curvilinear in middle-aged women and became almost linear in older women. With increasing age, the slope became steeper, and the increase started at lower BMI values. For hypertension, there was a marked increase in intercept from 75 years onward. In contrast, mortality risks were highest for low BMI (≤ 20) in all age groups. A clear U-shaped curve was observed only in the oldest age group.
  
  
  CONCLUSIONS
  The shapes of the relationships between BMI and incidence of diabetes, hypertension, and mortality change with age, suggesting that weight management interventions should be tailored for different age groups.
authors.affiliation: School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Australia; School of Public Health, University of Queensland, Brisbane, Australia. Electronic address: g.peeters@uq.edu.au.
authors.forename: G M E E Geeske
authors.initials: GM
authors.lastname: Peeters
authors.affiliation: School of Public Health, University of Queensland, Brisbane, Australia.
authors.forename: Gerrie-Cor M
authors.initials: GC
authors.lastname: Herber-Gast
authors.affiliation: School of Public Health, University of Queensland, Brisbane, Australia.
authors.forename: Annette J
authors.initials: AJ
authors.lastname: Dobson
authors.affiliation: School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Australia.
authors.forename: Wendy J
authors.initials: WJ
authors.lastname: Brown
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology*; D011793:Queensland / Q000453:epidemiology; D012189:Retrospective Studies; D016387:Women's Health