One Pill Makes you Smaller: The Demand for Anti-Obesity Drugs

The doubling of obesity in the U.S. over the last 25 years has led policymakers and physicians to encourage weight loss, but few methods of weight loss are effective. One promising avenue is pharmacotherapy. However, little is known about the use of anti-obesity drugs. This paper describes the market for anti-obesity drugs and studies the utilization of anti-obesity drugs using data from the Medical Expenditure Panel Survey for 1996-2002, a period that is interesting because it covers the introduction of three, and the withdrawal of two, anti-obesity drugs from the market. Our results point to wide sociodemographic disparities in anti-obesity drug use. Women are almost 200% more likely than men to use anti-obesity drugs. Hispanics and African-Americans are only 39% as likely as Whites to use them. Those with prescription drug coverage are 46% more likely to use anti-obesity drugs. We also find that the vast majority of subjects who are approved to take these drugs are not taking them, and a significant number who are not approved to take the drugs are taking them. We find strong evidence that the well-publicized 1997 withdrawal of fenfluramine and dexfenfluramine had a chilling effect on the overall market for anti-obesity drugs. We find little difference in observed characteristics between those who took the withdrawn drugs and those who took the other anti-obesity drugs in the market.