THE EFFECT OF WEIGHT LOSS ON HEALTH-RELATED QUALITY OF LIFE

Objective: Urinary incontinence (UI) and obesity are prevalent health conditions that adversely affect health-related quality of life (HRQOL) yet few data describe change in HRQOL with improvement in either condition. This study estimates the effect of change in UI frequency and weight on HRQOL measures among obese women with UI participating in a weight loss trial.

Methods: This is a longitudinal cohort analysis of 338 obese women with UI enrolled in the PRIDE trial and randomized to a behavioral weight loss intervention or a control condition. At baseline, 6 and 18 months, HRQOL was estimated with the Health Utilities Index Mark 3 (HUI3) and transformations of the SF-36 to preference-based measures (SF6D and Quality of Well-Being scale (QWB)). Potential predictors of changes in these outcomes were examined using general linear regression controlling for age, ethnicity, clinical site, and baseline weight, number of UI episodes and HRQOL.

Results: At baseline, mean (±SD) age of participants was 53±10 years, weight 97±17 kg and UI frequency 24±18 episodes/wk. Mean (median) SF-36 PCS was 48.5±8.1 (49.6), MCS was 49.8±9.8 (52.7) and mean HRQOL scores were HUI3 0.81±0.18 (0.85), SF6D 0.79±0.08 (0.79) and QWB 0.66±0.05 (0.67). Mean weight decreased by 6% and weekly UI frequency by 37% at 6 months and by 5% and 60%, respectively, at 18 months (all P<0.001). In multivariable analyses, HRQOL scores improved with weight loss at 6 and 18 months but were not independently associated with change in UI frequency after controlling for change in weight. Among the HRQOL measures examined, change in weight had the greatest effect on the HUI3 score (P<0.001 vs. SF-6D and QWB at 6months; test for interaction between HRQOL and weight loss).

Effect estimates of change in HRQOL scores with weight loss and decreased UI frequency

	HUI3		SF6D		QWB
	6 mo	18 mo	6 mo	18 mo	6 mo	18 mo
Weight (per 5 kg ↓)	0.042*	0.028*	0.012+	0.008+	0.009*	0.010*
UI frequency (per 7 episodes ↓ /wk)	0.012+	0.007	-0.001	0.001	0.001	0.002

* P<0.001; ⁺<0.01

Conclusion: Improved health-related quality of life was strongly associated with weight loss but not with improved UI. While all three measures improved with weight loss, our results suggest that the HUI3 is most sensitive to weight loss among women in this study.