title: A bi-directional relationship between obesity and health-related quality of life: evidence from the longitudinal AusDiab study.
abstract: OBJECTIVE
  To assess the prospective relationship between obesity and health-related quality of life, including a novel assessment of the impact of health-related quality of life on weight gain.
  
  
  METHODS
  Longitudinal, national, population-based Australian Diabetes, Obesity and Lifestyle (AusDiab) study, with surveys conducted in 1999/2000 and 2004/2005.
  
  
  METHODS
  A total of 5985 men and women aged ≥ 25 years at study entry.
  
  
  METHODS
  At both time points, height, weight and waist circumference were measured and self-report data on health-related quality of life from the SF-36 questionnaire were obtained. Cross-sectional and bi-directional, prospective associations between obesity categories and health-related quality of life were assessed.
  
  
  RESULTS
  Higher body mass index (BMI) at baseline was associated with deterioration in health-related quality of life over 5 years for seven of the eight health-related quality of life domains in women (all P ≤ 0.01, with the exception of mental health, P>0.05), and six out of eight in men (all P<0.05, with the exception of role-emotional, P=0.055, and mental health, P>0.05). Each of the quality-of-life domains related to mental health as well as the mental component summary were inversely associated with BMI change (all P<0.0001 for women and P ≤ 0.01 for men), with the exception of vitality, which was significant in women only (P=0.008). For the physical domains, change in BMI was inversely associated with baseline general health in women only (P=0.023).
  
  
  CONCLUSIONS
  Obesity was associated with a deterioration in health-related quality of life (including both physical and mental health domains) in this cohort of Australian adults followed over 5 years. Health-related quality of life was also a predictor of weight gain over 5 years, indicating a bi-directional association between obesity and health-related quality of life. The identification of those with poor health-related quality of life may be important in assessing the risk of future weight gain, and a focus on health-related quality of life may be beneficial in weight management strategies.
authors.affiliation: Clinical Diabetes and Epidemiology Department, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia. adrian.cameron@deakin.edu.au
authors.forename: A J
authors.initials: AJ
authors.lastname: Cameron
authors.forename: D J
authors.initials: DJ
authors.lastname: Magliano
authors.forename: D W
authors.initials: DW
authors.lastname: Dunstan
authors.forename: P Z
authors.initials: PZ
authors.lastname: Zimmet
authors.forename: K
authors.initials: K
authors.lastname: Hesketh
authors.forename: A
authors.initials: A
authors.lastname: Peeters
authors.forename: J E
authors.initials: JE
authors.lastname: Shaw
mesh_terms: D000328:Adult; D001315:Australia / Q000453:epidemiology; D001828:Body Image; D001835:Body Weight; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000523:psychology; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000453:epidemiology* / Q000523:psychology; D005260:Female; D006304:Health Status; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology* / Q000523:psychology; D010465:Perception; D011788:Quality of Life; D011795:Surveys and Questionnaires; D015430:Weight Gain