The share of patients who give up on popular weight loss drugs has a Minnesota pharmacy benefits manager concerned about the costs of prescribing them.

Eagan-based Prime Therapeutics announced study results Wednesday showing that only 32% of patients with obesity or prediabetes were still taking GLP-1a drugs for weight loss a year after they were prescribed.

The results question the cost-effectiveness of injectable drugs such as Wegovy and Saxenda that are widely promoted across social media, said David Lassen, Prime's chief clinical officer. "GLP-1a drugs and their use for weight loss have taken the health care industry by storm, but several issues must be resolved."

Prime found that total health care spending in 2021 was $7,727 higher for patients who started taking the drugs for weight loss than a control group of comparable patients. Spending was $13,218 higher for patients who adhered to the drugs over the entire year.

Follow-up research will determine if these patients end up costing less over time, because their weight loss prevents them from having costly diabetes and heart disease.

The drugs' potent weight-loss benefits appear reversible, so people who stop taking them in a few months might not improve their health long-term, Lassen said.

"That would mean, for 70% of those individuals, that this was a waste," he said.

GLP-1a drugs were first used to treat diabetes because they lowered blood sugar, but subsequent studies showed that they mimicked a hormone that delays the emptying of the stomach and forestalls hunger.

Many doctors have hailed the drugs as much-needed new tools to confront the U.S. obesity epidemic. About one-third of Minnesota adults are obese, according to surveys, one of the lowest rates in the nation. Another third of Minnesota adults are overweight.

Dr. Robert Gabbay, chief scientific and medical officer of the American Diabetes Association, said in a question-and-answer session Wednesday that these drugs are producing so much weight loss in studies that they are moving "into the territory of the benefits that we see with bariatric surgery." Pill forms of the drugs are under development.

Clinicians with the University of Kansas Health System similarly called the drugs "game-changers" in an online roundtable Wednesday, but said they are so powerful that they could result in malnutrition or patients exercising too little because they already are losing weight.

"Lifestyle [modification] from an activity and eating perspective is still really important, but we need to reposition it within the context of these pharmaceutical agents that are now very, very powerful," said John Jakicic, a KU weight management researcher.

One concern is that the drugs are promoted outside the clinical realm in TikTok videos and celebrity endorsements, Lassen said. Prime documented increased spending on the drugs shortly after social media promotions, he added.

Some posts included tips on how to get cheaper versions of the drugs from sources other than doctors. Lassen said that is troubling because the drugs gained federal approval through studies in which patients received them along with physician oversight and other weight-loss strategies.

The Prime study could show what happens outside of such a tightly controlled environment, when patients take the drugs with minimal oversight.

"It tells us that those studies, although they showed results, maybe weren't real world," Lassen said.

Interest in the drugs is rising, but some patients stop taking them because of cost, the hassle of injections, stomach problems or other side effects, said Dr. Richard Bergenstal of HealthPartners Institute's International Diabetes Center in St. Louis Park. European regulators recently expanded their investigation of the drug class based on rare reports of patients contemplating suicide.

Prime for now is recommending that insurers require prior authorization of these drugs for weight loss before agreeing to pay for them.