Adherence to weight loss medications; post-marketing study from HMO pharmacy data of one million individuals
Introduction
Weight loss is the most effective way to lower glycaemia in type 2 diabetes [1]. Obesity, followed by type 2 diabetes, has increased dramatically around the world [2] since the 1980s [3], [4], with concomitant interest among health care providers and consumers in weight-loss drugs.
Most clinical trials of weight-loss medications have been funded by pharmaceutical companies [5], in which patients did not pay for the treatment and were preselected for their ability to adhere to and to tolerate treatment; such trials may over-estimate the beneficial effect of those drugs in a general population setting. A meta-analysis [6] of 30 long-term weight-loss pharmacotherapy trials reported average attrition rates of 30–40%. In that meta-analysis, compared with a placebo, orlistat, a gastrointestinal lipase inhibitor, reduced weight by an average of 2.9 kg and sibutramine, a centrally acting monoamine reuptake inhibitor, reduced weight by 4.2 kg [6]. Orlistat reduces the incidence of diabetes and improves levels of total cholesterol and low density lipoprotein cholesterol (LDL-C), blood pressure, and glycemic control in patients with diabetes, but causes gastrointestinal side effects and slightly lowers levels of high density lipoprotein (HDL-C) [6], [7]. Sibutramine improve levels of HDL-C and triglycerides, raises blood pressure and pulse rate [6], and was banned by the US Food and Drug Administration in 2010 [8].
To assess the usage and adherence to weight-loss drugs in a free living population, including diabetes patients, we utilized a computerized prescription system of a large Health Maintenance Organization (HMO), serving over one million adult members. We conducted a 5-year trend analysis and 12-month follow-up of individuals since their first purchase, during which time orlistat and sibutramine were approved for treatment of obesity for longer than 1 year [9].
Section snippets
HMO database
Maccabi Healthcare Services is Israel's second largest HMO, serving over 1.8 million members. The patient information systems are fully computerized and capture visits to hospitals, physicians, and other health professionals, prescription drug purchases, laboratory testing, and imaging studies. Available data for all prescription drug purchases covered by the HMO include identification numbers for the patient and prescribing physician, date and place of purchase, and drug classification number.
Trends and characteristics
The HMO population aged 21 years and over grew from 1,021,868 to 1,115,079 during the 5 years; purchases of weight-loss medications increased during this interval from 9797 to 35,200 purchases/year. Incidence of new users per 10,000 was three times higher for sibutramine as compared to orlistat (Fig. 1). Women had consistently higher rates of use of weight-loss medication than men (Appendix, Figs. 1 and 2). Use of weight loss medication varied with age; incidence was highest in the 41–50 and
Discussion
In this HMO serving over million adult members, use of weight loss medications increased substantially during the study period of 2003–2007. Users of sibutramine outnumbered those using orlistat by 3–1. Use of these medications was more frequent in women, in members with diabetes and heart disease, and persons with supplemental health insurance. However, most users discontinued therapy after a short time, with average duration of use of 2.1 months for orlistat and 2.9 months for sibutramine.
Conflict of interest
The authors declare that they have no conflict of interest.
Acknowledgments
We would to thank Dr. Nurit Friedman, Dr. Barbara G. Silverman, and Jenny Kertes from the Research and Evaluation unit, Maccabi Healthcare Services, Tel-Aviv, Israel, for their significant contribution for this study.
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