Development and validation of a French obesity-specific quality of life questionnaire: Quality Of Life, Obesity and Dietetics (QOLOD) rating scale

Abstract

To develop and validate a new health related quality of life (HRQOL) questionnaire specific to obesity and its management. This study was in two parts. The first (Study 1) consisted of the creation of a new tool derived from the American "Impact of Weight on Quality of Life Questionnaire" (IWQOL, 74 items) by adding to it a 17 items specific complementary module. This initial questionnaire (91 items) was reduced so as to obtain a questionnaire adapted to socio-cultural factors of obesity and dietary weight management in France. The objective of the second (Study 2) was to validate this final questionnaire by evaluating its psychometric properties: construction validity, internal reliability, concurrent validity in relation to a generic questionnaire, the SF-12, clinical validity by studying the effects of age, gender and body mass index (BMI), and reproducibility. The results of Study 1, obtained in 128 obese patients (mean age: 42.5 12.1, BMI: 34.5 2.8 kg/m2, women: 83.6%) enabled reduction of the 91 questionnaire items to 36, grouped into 5 dimensions: physical impact, psycho-social impact, sex life, comfort with food and diet experience. Two hundred and twelve patients (mean age: 43.3 12.2, BMI: 35.8 7.4 kg/m2, women: 77.7%) were included in Study 2, among whom 75 filled out the questionnaire twice at a one week interval. Analyses enabled verification of the construction validity and internal reliability (Cronbach alpha > 0.7) of the questionnaire as well as its concurrent validity in relation to summarized SF-12 scores and its clinical validity. The "physical impact" dimension was significantly influenced by BMI and age, the dimensions "sex life" and "diet experience" by the factors gender and BMI, while "psycho-social impact" was influenced by the 3 factors cited. Its reproducibility was also deemed satisfactory (intra-class correlation coefficient > 0.8). This new questionnaire, called the "Echelle Qualité de Vie, Obésité et Diététique (EQVOD)"/"Quality of Life, Obesity and Dietetics (QOLOD)" rating scale is sufficiently reliable and reproducible to be used in clinical practice. It is a simple tool adapted to socio-cultural factors of obesity in France, enabling taking into account of the effects of dietary management on the HRQOL of obese people.