Assessing quality of life in severe obesity : development and psychometric properties of the ORWELL-R

Abstract

PURPOSE: Several health-related quality-of-life (HRQoL) dimensions are affected by obesity. Our goal was to characterize the psychometric properties of the ORWELL-R, a new obesity-related quality-of-life instrument for assessing the "individual experience of overweightness". METHODS: This psychometric assessment included two different samples: one multicenter clinical sample, used for assessing internal consistency, construct validity and temporal reliability; and a community sample (collected through a cross-sectional mailing survey design), used for additional construct validity assessment and model fit confirmation. RESULTS: Overall, 946 persons participated (188 from the clinical sample; 758 from community sample). An alpha coefficient of 0.925 (clinical sample) and 0.934 (community sample) was found. Three subscales were identified (53.2 % of variance): Body environment experience (alpha = 0.875), Illness perception and distress (alpha = 0.864), Physical symptoms (alpha = 0.674). Adequate test-retest reliability has been confirmed (ICC: 0.78 for the overall score). ORWELL-R scores were worse in the clinical sample. Worst HRQoL, as measured by higher ORWELL-R scores, was associated with BMI increases. ORWELL-R scores were associated with IWQOL-Lite and lower scores in happiness. CONCLUSIONS: ORWELL-R shows good internal consistency and adequate test-retest reliability. Good construct validity was also observed (for convergent and discriminant validity) and confirmed through confirmatory factor analysis (in both clinical and community samples). Presented data sustain ORWELL-R as a reliable and useful instrument to assess obesity-related QoL, in both research and clinical contexts.