Cost-effectiveness of a low-carbohydrate diet
Nutrition Research Newsletter, Dec, 2005
Save a personal copy of this article and quickly find it again with Furl.net. It's free! Save it.
Obesity is a huge public health problem, costing the United States more than tobacco or alcohol abuse. The efficacy of obesity treatment using group lifestyle modification has been previously shown. Additionally, evidence is emerging that lifestyle modification is a cost-effective treatment. Low-carbohydrate diets (for example, the Atkins diet) have been a very popular approach for weight loss in recent years. Five randomized trials have reported comparisons of low-carbohydrate and standard diets. In the three studies that followed subjects for 1 year, no differences in weight loss were seen between patients following carbohydrate-restricted diets versus those following calorie- or fat-restricted diets.
The goal of a recent study was to assess the relative cost-effectiveness of low-carbohydrate and standard diets for weight loss, using data from the randomized trial by Stem et al. While the 1-year results of the study did not show statistically significant differences in weight between the two groups, investigators had reasons to believe that the low-carbohydrate diet might be cost-effective relative to the standard diet. First, there was greater initial weight loss in the low-carbohydrate arm during the first 6 months of the study (that is, weight was lost more quickly in the carbohydrate-restricted group). Second, there is evidence to suggest that high-protein diets may induce greater satiety. For these two reasons, researchers believed that patients in the low-carbohydrate arm would experience lower costs and/or more quality-adjusted life years (QALY) during the trial.
The trial was a randomized evaluation of low-carbohydrate and standard diets, conducted at the Philadelphia Veterans Administration Medical Center. One-hundred thirty-two severely obese participants (mean BMI 42.9), with a high prevalence of diabetes (39%) or metabolic syndrome (43%), were randomized to one of the two diets. Greater than half the subjects were African American, and 17% were women. Subjects in both arms of the study received weekly group counseling sessions during the first moth, followed by monthly group sessions for the next 5 months. Individuals in the standard arm were counseled to follow the National Cholesterol Education Program Step I diet (including restriction of calories, total fat, saturated fat, and cholesterol), and persons in the low-carbohydrate arm were counseled to consume < 30 g per day of carbohydrate.
A cost-effectiveness analysis was performed_ Researchers took a societal perspective for the analysis. They included both health care costs (for example, cost of the intervention) and nonhealth care cost (for example, cost of low work time). Costs of the intervention and of other therapies used by participants in the study were estimated. They estimated the cost of the intervention using hourly dietitians' wages in the Veterans Health Administration (VHA). Other health care costs were taken from VHA economics databases. The cost of lost work time for study participants was included. Data from Medical Outcome Study Short Form 36 questionnaires that study participants completed at zero months, 6 months, and 12 months were used to derive a preference score. The incremental cost-effectiveness ratio (CER) was defined as the difference in costs divided by the difference in QALYs.
Total costs during the one year of the trial were $6742 [+ or -] 6675 and $6249 4 [+ or -] 5100 for the low-carbohydrate and standard groups, respectively (p = 0.78). Participants experienced 0.64 [+ or -] 0.02 and 0.61 [+ or -] 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/QALY (that is, 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/QALY, $1000,000/QALY, and $150,000/QAYL, were 72.4%, 78.6%, and 79.8%, respectively.
The low-carbohydrate diet was not more cost-effective for weight loss when compared with the standard diet.
A. Tsai, H. Glick, D. Shera, et al. Cost-effectiveness of a low-carbohydrate diet and a standard diet in severe obesity. Obes Res; 13:1834-1840 (October 2005). [Correspondence: Adam Gilden Tsai, Weight and Eating Disorders Program, 3535 Market Street, Third floor, University of Pennsylvania, Philadelphia, PA 19104. E-mail:
gildena@mail.med.upenn.edu].