title: Performance of two self-report measures for evaluating obesity and weight loss.
abstract: OBJECTIVE
  To evaluate performance of the Obesity and Weight-Loss Quality-of-Life (OWLQOL) and Weight-Related Symptoms (WRSM) measures.
  
  
  METHODS
  Four studies of obese persons 18 to 75 years of age were analyzed: a 12-week initial validation study, a clinical trial using blinded endpoint data at 50 to 83 weeks, and community studies conducted in the U.S. and Europe. Fifty-six initial validation study subjects visited 1 week after screening to evaluate reproducibility.
  
  
  RESULTS
  Overall, 6107 obese persons completed one assessment, 291 completed follow-up at 12 weeks, and 642 at >50 weeks. Psychometric analyses resulted in a 17-item OWLQOL with a single score tested on five samples that was internally consistent (alpha values > 0.90) and reproducible (intraclass correlation coefficient > 0.95). The OWLQOL score (higher is better) was associated, as expected, with the symptom measure (lower is better, -0.54), generic quality of life measure (0.53), and measures of physical (0.40) and mental functioning (0.47). The 20-item WRSM was internally consistent (alpha = 0.87) and reproducible (intraclass correlation coefficient = 0.83). The OWLQOL discriminated between genders (p < 0.001), presence of disability days (p < 0.05), levels of BMI (p < 0.05), and levels of symptom bothersomeness (p < 0.001). Evaluation at 12 weeks yielded an effect size for > or = 2.5% weight loss of 0.77 for the OWLQOL and -0.54 for the WRSM. At > or = 50 weeks for > or = 10% weight change, effect sizes were 1.63 and -0.73, respectively.
  
  
  CONCLUSIONS
  The OWLQOL and WRSM are brief, valid, reproducible, and responsive self-reported outcomes for evaluating obesity and weight loss.
authors.affiliation: Department of Health Services, University of Washington, Seattle, Washington 98195, USA. donald@u.washington.edu
authors.forename: Donald L
authors.initials: DL
authors.lastname: Patrick
authors.forename: Donald M
authors.initials: DM
authors.lastname: Bushnell
authors.forename: Margaret
authors.initials: M
authors.lastname: Rothman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology / Q000523:psychology* / Q000628:therapy*; D011788:Quality of Life; D015203:Reproducibility of Results; D012647:Self-Assessment; D011795:Surveys and Questionnaires; D015431:Weight Loss