Prime Therapeutics Finds No Medical Cost Offsets for GLP-1 Obesity Drugs | AMCP Annual 2025

A real-world study conducted by Prime Therapeutics has found that the use of GLP-1 drugs to treat obesity in patients added to healthcare costs with no medical cost offsets, according to a poster presented at the annual meeting of the Academy of Managed Care Pharmacy in Houston.

Prime Therapeutics researchers found in their analysis of real-world data an increase in total costs for patients who were taking GLP-1 therapies to treat obesity but did not have diabetes. The medical cost increased for the GLP-1 treatment group by an average of $1,338 per member, compared with a matched control group.

The demand for GLP-1 drugs such as Wegovy and Zepbound for weight loss is increasing. A PwC survey in October 2024 found that 8% to 10% of Americans are currently taking GLP-1 drugs, and 30% to 35% of Americans are interested in using them.

Wegovy (semaglutide) was approved to treat obesity in June 2021, and it is available as a once-weekly, single-dose pen. Its list price is $1,349. In March, Novo Nordisk is offering cash-paying customers a price of $499. Lilly also lowered the prices of several doses of Zepbound (tirzepatide) for patients purchasing the obesity medication through the self-pay program. Zepbound is available for a list price of $1,059.87 a month.

Drugs for weight management accounted for about half of the total increase in drug spend in 2024, according to a recent analysis from Evernorth. In fact, GLP-1 drugs for weight loss were the predominant driver, equating to 6.7% of total drug costs. Evernorth is projecting a 73.1% increase in utilization for weight loss drugs in 2025.

The impact on the healthcare system could be huge if the GLP-1 therapies could address the diseases associated with obesity. In fact, obesity is a factor in a wide range of illnesses (e.g., heart disease, stroke and arthritis) that can result in a cascade of costly pharmaceutical and medical treatments. Intuitively, the anti-obesity effects of the GLP-1s should yield savings from avoided illness and treatment for it.

But so far, though, the jury is still out on whether anti-obesity drugs and specifically the GLP-1 therapies positively impact overall healthcare costs. “Currently, there is scant GLP-1 weight loss treatment without diabetes mellitus real-world cost-effectiveness information beyond 1 year,” researchers from Prime Therapeutics said in the poster.

In this study, researchers from Prime Therapeutics wanted to assess the changes in annual total cost of care. They looked at costs one year before the initiation of therapy and two years after patient began treatment for obesity compared with a matched control group.

This retrospective study analyzed Prime Therapeutics’ integrated pharmacy and medical claims data from Jan. 1, 2020, through Dec. 31, 2023. Prime officials looked at data for patients who were started treatment for obesity during the time period and who did not have diabetes. Total cost of care was calculated after all provider discounts were applied, but pharmaceutical company rebates and coupons were not included.

The analysis was based on a cohort was 3,046 members who were using a GLP-1 therapy for weight loss and 8,653 control group members. Prime used a difference-in-difference statistical method for evaluating the impact before treatment and two years after treatment.

Among the group that was using a GLP-1 therapy the average annual total cost of care increased from $12,695 in the year before the initiation of therapy to $20,165 in year 1, a $7,470 (56.0%) increase, and was $18,507 in year 2, a $5,812 (45.8% over the year before treatment) increase.

Among those in the control group, the average annual total cost of care increased from $11,406 the year before treatment to $11,882 in year 1, a $476 (4.1%) increase, and was $13,012 in year 2, a $1,606 (14.1% over year before treatment) increase.

The difference-in-difference comparison found that GLP-1 group had significantly higher per-member annual total cost of care $6,994 in year 1 compared with the year before treatment; and $4,206 higher in year 2 compared with the year before treatment. Researchers found that the differences were driven by higher annual per-member pharmacy cost in the GLP-1 group compared with the control group.

The study also found that per-member annual medical benefit cost trended higher but not significantly different in the GLP-1 group compared with the control group for both years analyzed.