Cost-effectiveness of a low-carbohydrate diet and a standard diet in severe obesity.

Author: Tsai AG, Glick HA, Shera D, Stern L, Samaha FF

Author affiliation: Division of General Internal Medicine, Department of Medicine, Weight and Eating Disorders Program, University of Pennsylvania, Philadelphia, PA 19104, USA. gildena@mail.med.upenn.edu

Publication date & source: 2005.10, Obes Res., 13(10):1834-40.

Publication type: Randomized Controlled Trial; Research Support, N.I.H., Extramural

OBJECTIVE: Low-carbohydrate diets have become a popular alternative to standard diets for weight loss. Our aim was to compare the cost-effectiveness of these two diets. RESEARCH METHODS AND PROCEDURES: The patient population included 129 severely obese subjects (BMI = 42.9) from a randomized trial; participants had a high prevalence of diabetes or metabolic syndrome. We compared within-trial costs, quality-adjusted life years (QALYs), and the incremental cost-effectiveness ratio (CER) for the two study groups. We imputed missing values for QALYs. The CER was bootstrapped to derive 95% confidence intervals and to define acceptability cut-offs. We took a societal perspective for our analysis. RESULTS: Total costs during the one year of the trial were 6742 dollars +/- 6675 and 6249 dollars +/- 5100 for the low-carbohydrate and standard groups, respectively (p = 0.78). Participants experienced 0.64 +/- 0.02 and 0.61 +/- 0.02 QALYs during the one year of the study, respectively (p = 0.17 for difference). The point estimate of the incremental CER was -1225 dollars/QALY (i.e., the low-carbohydrate diet dominated the standard diet). However, in the bootstrap analysis, the wide spread of CERs caused the 95% confidence interval to be undefined. The probabilities that the low-carbohydrate diet was acceptable, using cut-offs of 50,000 dollars/QALY, 100,000 dollars/QALY, and 150,000 dollars/QALY, were 72.4% 78.6%, and 79.8%, respectively. DISCUSSION: The low-carbohydrate diet was not more cost-effective for weight loss than the standard diet in the patient population studied. Larger studies are needed to better assess the cost-effectiveness of dietary therapies for weight loss.