More than half of people prescribed weight-loss drugs Saxenda and Wegovy over the past decade ended their treatment too early to realize meaningful health benefits, according to a study by a major U.S. health insurer.

The Blue Cross Blue Shield Association analyzed the pharmacy and medical claims of nearly 170,000 people between July 2014 and December 2023 and found that 58% didn't complete a 12-week course of the medications liraglutide or semaglutide, which are sold under the brand names Saxenda and Wegovy.

Nearly 1 in 3 patients halted treatment within four weeks, before the recommended dosage reached the drugs' targeted strength. Because these patients dropped out before completing the recommended treatment, they were less likely to achieve the medical benefits of weight loss, the study said.

Blue Cross Blue Shield Association is a federation of dozens of for-profit and nonprofit companies that provide health insurance for about 118 million people in 50 states. The insurer released the non-peer-reviewed data to inform decisionmakers and the public about how these two wildly popular weight-loss drugs are being used and to "paint a clearer picture of what makes somebody successful," said Razia Hashmi, vice president for clinical affairs at Blue Cross Blue Shield.

A spokeswoman for Novo Nordisk, which markets Saxenda and Wegovy, declined to comment on the study, which has not been published in an independent medical journal.

This class of weight-loss medications, called GLP-1 (glucagon-like peptide-1) receptor agonists, has become immensely popular with consumers. Quarterly sales of anti-obesity drugs surpassed $1.1 billion midway through 2023, according to a report from the Congressional Budget Office.

These drugs were initially used to treat diabetes. Drugmakers later won approval to market them for weight loss and heart disease. Drug companies continue to study other potential uses for GLP-1s, which can cost more than $10,000 per year out of pocket.

Because the drugs are so widely prescribed and expensive, Hashmi said it's important to understand how patients are using these drugs to lose weight and whether they're achieving health benefits. It's also critical to understand why such a large portion of patients have quit the medications before they'd gotten up to the right dosage to begin reaping the benefits.

The study said patients prescribed weight-loss drugs by an endocrinologist or obesity specialist were likelier to stick with them longer. Patients who had visited their doctor or other prescriber frequently during the first 12 weeks were also more likely to continue taking the medications. The study found that young adults between 18 and 34 were more likely to ditch the medication before completing the prescribed course.

Saxenda, which requires daily injections, was the only GLP-1 drug approved for weight loss from 2014 to 2021. The study said fewer than 6,000 individuals began the medication each year during that period.

When Wegovy gained Food and Drug Administration approval for weight loss in 2021 as a weekly injectable, prescriptions soared, reaching nearly 121,000 scripts in 2023, the study said.

Employers and health insurance plans are attempting to slow spending on these drugs. Many insurers have imposed requirements such as prior authorization or step therapy, which mandates that people try less expensive drugs first. In some cases, employers and insurers are denying coverage altogether.

The study did not address how different Blue Cross Blue Shield insurance plans cover these weight-loss medications. Hashmi said Blue Cross Blue Shield won’t use this evidence for coverage decisions.

“Our coverage decisions are always based on published, evidence-based studies and literature,” Hashmi said.  “This study is adding to the knowledge about real-world evidence. But until it's published and peer-reviewed and critiqued, it wouldn't be part of the criteria.”

James Gelfand, president and CEO of the ERISA Industry Committee, which represents companies that provide employee benefits, said employers will scrutinize whether patients stick with these medications.

"It can take a year or more to get real results from these $1,000-per-month weight loss medications," Gelfand said. "When patients quit early, as most patients do, that money was wasted. And the result is higher health insurance costs for everyone on their employer's health plan."

Ken Alltucker is on X at @kalltucker, contact him by email at [email protected].