The relationship between health-related quality of life and weight loss

Objective: This is a report of health-related quality of life (HRQOL) changes in obese patients completing at least I year of outpatient treatment in a weight reduction program combining phentermine-fenfluramine and dietary counseling. Research Methods and Procedures: Participants were 141 women (87.6%) and 20 men (12.4%) who had an average body mass index at intake of 41.1 kg/m(2) (SD = 7.0, range = 29.5 to 67.0 kg/m(2)) and an average age of 44.9 years (SD = 9.3, range 23 to 65 years). HRQOL was assessed at intake and at 1-year follow-up using the Impact of Weight on Quality of Life (IWQOL)-Lite questionnaire. The relationship between HRQOL changes and weight loss was examined using Pearson correlations. Clinically meaningful change in HRQOL was defined as a 1.96 SEM reduction in IWQOL-Lite total score. Results: On average, participants lost 20.2 kg or 17.6% of their weight over the 1-year period. Of the participants, 15.5% lost < 10% of their weight, 24.2% lost 10% to 14.9%, 23.6% lost 15% to 19.9%, and 36.6% lost 20% or more. All five IWQOL-Lite scales and total score showed statistically significant improvement over the 1-year period. Changes in IWQOL-Lite scores from intake to 1 year showed statistically significant correlations with percentage of weight loss for all subscales and total score. Subscale correlations with weight loss ranged from 0.166 (Public Distress) to 0.396 (Physical Function) and was 0.370 for the total score. Forty-four percent of participants losing < 10% met the criterion of clinically meaningful change, compared with 51.3% losing 10% to 14.9%, 55.3% losing 15% to 19.95%, and 76.3% losing > 20%. For total score and for three of the five IWQOL-Lite scales (Physical Function, Self-Esteem, and Sexual Life), the relationship between weight loss and clinically meaningful change was linear and was significant at p < 0.05. Physical Function and Self-Esteem were most strongly affected by weight loss. Discussion: HRQOL changes, as measured by an obesity-specific instrument (IWQOL-Lite), are strongly related to weight reduction.