Association between Health-Related Quality of Life and Body Mass After Adjustable Gastric Banding: A Nonlinear Approach

Objective: To estimate the relationship between health utilities and body mass index (BMI) among a cohort of obese patients who underwent laparoscopic adjustable gastric banding (LAGB). Methods: We used a cross-sectional survey to ascertain demographic, clinical, and health utility data from patients who had undergone LAGB in Washington State from 2004 to 2010. The EuroQol five-dimensional (EQ-5D) questionnaire was used for health utility estimation. We calculated adjusted EQ-5D questionnaire indices across BMI categories by using a two-part model. We also used logistic regression to examine the relationship between BMI and the likelihood of reporting problems on each of the EQ-5D questionnaire dimension. Results: Data were obtained from 790 subjects. The mean adjusted EQ-5D questionnaire indices for all obese BMI categories were significantly lower than those in the normal weight category. The relationship between BMI and EQ-5D questionnaire indices was nonlinear. Respondents classified as morbidly obese II (BMI > 50 kg/m(2)) had the greatest decrement (-0.15, 95% confidence interval -0.28 to -0.01) in EQ-5D questionnaire indices. The association between EQ-5D questionnaire indices and BMI at the time of the survey was weaker after adjusting for weight loss after LAGB. Respondents with higher BMI were more likely to report having problems in the mobility, usual/activity, pain/discomfort, and anxiety/depression dimensions (trend test, P < 0.05), but not for the self-care dimension (trend test, P = 0.08). Conclusions: The EQ-5D questionnaire has a negative and nonlinear relationship with BMI for obese patients who had LAGB. The relationship is confounded by weight loss. Within the EQ-5D questionnaire dimensions, patients are more likely to report having problems in the mobility, usual/activity, pain/discomfort, and anxiety/depression dimensions in higher BMI categories, but not in the self-care dimension.