Popular new anti-obesity medications can help patients lose 10 to 20 percent of their body weight, but a new study finds that about 40 percent of prescriptions for these drugs are never filled. Researchers say cost is likely a key reason.
The study focuses on GLP-1 medications, a class of drugs widely used to treat obesity and diabetes. Despite their effectiveness, the drugs remain expensive, costing about $900 a month for patients without insurance. Debate has largely centered on pricing and whether public programs such as Medicare should cover them.
Less understood is how patients with insurance use these drugs. To address that gap, Anna Sinaiko, an associate professor of health economics and policy at the Harvard T.H. Chan School of Public Health, led a multi-institutional research team examining prescription use among insured patients.
Using electronic medical records from the University of Colorado Health System linked to pharmacy claims, the researchers analyzed 9,848 GLP-1 prescription orders from 6,094 patients. Their findings, published in JAMA Health Forum, show that only 60.1 percent of prescriptions were filled.
Filling rates varied by race and ethnicity. About 60.9 percent of white patients filled their prescriptions, compared with 58.4 percent of Hispanic patients and 55.3 percent of Black patients.
Even with insurance, patients faced notable out-of-pocket costs. On average, co-pays and other expenses totaled $71.90 per prescription. White patients paid the most, at $78.37 on average, followed by Hispanic patients at $63.69 and Black patients at $41.15.
The dataset did not capture reasons why prescriptions went unfilled. Sinaiko said concerns about side effects may play a role, but financial pressure is likely significant. Patients with both diabetes and obesity were more likely to fill prescriptions than those with diabetes alone, who in turn were more likely than patients treated only for obesity. Patients with obesity alone also faced the highest out-of-pocket costs.
The pattern suggests that cost influences whether patients start treatment, even when insurance covers part of the expense. Monthly costs of $60 to $100 may still be unaffordable for many patients, Sinaiko said.
The findings also point to broader challenges in the healthcare system. Disparities in access persist among racial and ethnic minority groups and lower-income patients, even when they have insurance coverage.
Medication non-adherence is another concern, particularly for chronic conditions such as obesity and diabetes. Sinaiko said future research should examine how clinicians respond when patients do not pick up prescriptions, including whether they switch patients to lower-cost alternatives.
The market for GLP-1 drugs is also changing. New medications are in development, and insurers are expected to tighten coverage to control costs. In November, President Donald Trump announced agreements with Eli Lilly and Novo Nordisk to lower prices to as little as $149 a month for Medicare, Medicaid, and self-paying patients.
While that represents a sharp price cut, Sinaiko said it may do little to improve access or reduce disparities. In the study, many patients declined treatment even when their out-of-pocket costs were lower than $149.
The results underscore affordability as a central barrier to care. Improving access to high-value medications, Sinaiko said, will require sustained attention to what patients can realistically afford.
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