CONSTRUCT-VALIDITY OF THE IMPACT OF WEIGHT ON QUALITY-OF-LIFE QUESTIONNAIRE

The impact of Weight on Quality of Life questionnaire (IWQOL) is a 74- item self-report, condition-specific instrument that (1) assesses the effect of weight on quality of life in eight key areas, and (2) may be used as a treatment outcome measure and/or an evaluation tool for hea lthcare policy makers and third-party payers. This study explores IWQO L construct validity and provides new information on internal consiste ncy, treatment effects, and differences between men and women. IWQOL t otal scores correlated highly with other measures of overall quality o f life, and subscale scores correlated well with counterparts in the a ssessment battery, Internal consistency estimates for the IWQOL scales generally were high. For the women, 4-week participants, and the tota l sample, pretreatment-posttreatment differences were significant for all IWQOL scales and total score, For men, treatment differences were significant for the total score and all subscales except for Work and Mobility. Treatment differences for 2-week participants were significa nt for all scales except for Work. Consistent with previous IWQOL stud y results, the Comfort With Food scale scores reflected more discomfor t at posttreatment as compared with pretreatment, The IWQOL, already t ranslated into French and Italian, currently is demonstrating clinical and research utility as a quality-of-life outcome measure for clinica l trials of antiobesity drugs and surgical treatments for patients wit h obesity.