Psychometric evaluation of a Brazilian version of the impact of weight on quality of life (IWQOL-Lite) instrument

Purpose The impact of weight on quality of life (IWQOL‐Lite) is a self‐administered instrument that assesses quality of life in obesity. It is composed of 31 items and five domains (physical function, self‐esteem, sexual life, public distress, and work). The aim of the present study was to evaluate reliability (test‐retest), internal structure, construct validity and discriminant validity. Methods IWQOL‐Lite scores were obtained from 89 people in a Weight Watchers institution (clinical sample) and 156 community volunteers (community sample). The participants were selected based on the same criteria: gender (female) and age (> 24 years), except for BMI. The community sample also completed the SF‐36, a generic measure of health‐related quality of life. Results The Brazilian IWQOL‐Lite demonstrated good test‐retest reliability, internal consistency, discriminative validity and convergent validity. Conclusions The IWQOL‐Lite is the first specific instrument validated in Brazil for assessing quality of life in obesity. The results reveal that IWQOL‐Lite is an instrument with good psychometric properties. Nevertheless, in some cases results were dissimilar to those reported in earlier studies using the original American English. Copyright © 2010 John Wiley & Sons, Ltd and Eating Disorders Association.