title: One-year health-related quality of life outcomes in weight loss trial participants: comparison of three measures.
abstract: BACKGROUND
  The literature on changes in health-related quality of life (HRQOL) in weight loss studies is inconsistent, and few studies use more than one type of measure. The purpose of the current study was to compare one-year changes in HRQOL as a function of weight change using three different measures: a weight-related measure (Impact of Weight on Quality of Life-Lite [IWQOL-Lite)]) and two generic measures (SF-36; EQ-5D).
  
  
  METHODS
  Data were obtained from 926 participants (mean Body Mass Index (BMI) (kg/m(2)) = 35.4; 84% female; mean age = 49.5 years) in a placebo-controlled randomized trial for weight loss. At baseline and one-year, participants completed all three HRQOL measures. HRQOL was compared across weight change categories (> or = 5% and 0-4.9% gain, 0-4.9%, 5.0-9.9% and > or = 10% loss), using effect sizes.
  
  
  RESULTS
  The weight-related measure of HRQOL exhibited greater improvements with one-year weight loss than either of the generic instruments, with effect sizes ranging from 0.24 to 0.62 for 5-9.9% weight reductions and 0.44 to 0.95 for > or = 10% reductions. IWQOL-Lite Self-Esteem also showed a small improvement with weight gain. Changes in the two generic measures of HRQOL were inconsistent with each other, and in the case of the SF-36, variable across domains. For participants gaining > or = 5% of weight, the greatest reductions in HRQOL occurred with respect to SF-36 Mental Health, MCS, and Vitality, with effect sizes of -0.82, -0.70, and -0.63 respectively.
  
  
  CONCLUSIONS
  This study found differences between weight-related and generic measures of health-related quality of life in a one-year weight loss trial, reflecting the potential value of using more than one measure in a trial. Although weight loss was generally associated with improved IWQOL-Lite, physical SF-36 subscale and EQ-5D scores, a small amount of weight gain was associated with a slight improvement on weight-specific HRQOL and almost no change on the EQ-5D, suggesting the need for further research to more fully study these relationships. We believe our findings have relevance for weight loss patients and obesity clinicians/researchers in informing them of likely HRQOL outcomes associated with varying amounts of weight loss or gain.
authors.affiliation: Obesity and Quality of Life Consulting, 762 Ninth Street #563, Durham, North Carolina 27705, USA. rkolotkin@qualityoflifeconsulting.com
authors.forename: Ronette L
authors.initials: RL
authors.lastname: Kolotkin
authors.forename: Josephine M
authors.initials: JM
authors.lastname: Norquist
authors.forename: Ross D
authors.initials: RD
authors.lastname: Crosby
authors.forename: Shailaja
authors.initials: S
authors.lastname: Suryawanshi
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Teixeira
authors.forename: Steven B
authors.initials: SB
authors.lastname: Heymsfield
authors.forename: Ngozi
authors.initials: N
authors.lastname: Erondu
authors.forename: Allison M
authors.initials: AM
authors.lastname: Nguyen
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008603:Mental Health; D008875:Middle Aged; D009765:Obesity / Q000523:psychology / Q000628:therapy; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011594:Psychometrics / Q000379:methods*; D011788:Quality of Life; D016032:Randomized Controlled Trials as Topic; D011795:Surveys and Questionnaires; D015431:Weight Loss