The study, conducted by researchers at the University of Mississippi School of Pharmacy in partnership with the Mississippi Division of Medicaid and published in Advances in Therapy, analyzed deidentified administrative claims from January 2023 through December 2025. The team identified 8,495 GLP-1 receptor agonist users overall and narrowed the cohort to 3,968 adults who initiated therapy between July 2023 and June 2025, each with six months of continuous enrollment before and after starting the medication. The population was strikingly homogeneous: 92.52 percent were female, 50.28 percent were Black, and nearly 62 percent were younger adults aged 18 to 39. Hypertension and depression were the most common coexisting conditions, and most members were enrolled in managed care organizations rather than fee-for-service plans.

The headline numbers tell a story of steady erosion. Mean adherence, measured by the proportion of days covered, a standard metric that divides the total days a patient has medication on hand by the total days in the observation window, stood at 0.76 at three months but fell to 0.65 by six months. The proportion of members meeting the conventional adherence threshold of at least 80 percent of days covered dropped from 56.85 percent at three months to 38.16 percent at six months. Persistence, defined as continuous therapy without a gap of 60 days or more, followed the same downward slope, falling from 72.98 percent to 51.03 percent over the same interval. In the subgroup followed for a full year, mean adherence sank to 0.54, with only 25.26 percent adherent and 36.67 percent persistent.

What makes this study particularly valuable is its timing. Most prior real-world analyses of GLP-1 adherence were conducted during the nationwide drug shortage that ran from 2022 through February 2025, a period when supply constraints made it nearly impossible to distinguish voluntary discontinuation from involuntary interruption. Because this analysis extends through December 2025, it captures one of the first pictures of adherence under conditions of stable drug availability. The researchers found that adherence improved progressively across initiation cohorts: members who started therapy in the first half of 2025 consistently outperformed those who began in 2024, who in turn fared better than the 2023 pioneers. Among 2023 initiators, only 47.77 percent were adherent at three months, compared with 61.01 percent of 2025 initiators.

To move beyond aggregate statistics, which can mask enormous individual variation, the team employed group-based trajectory modeling, a statistical technique that clusters individuals who follow similar longitudinal patterns of behavior. The model input was the continuous proportion of days covered calculated for each 30-day interval, and the optimal five-group quadratic solution was selected using the Bayesian Information Criterion, the logged Bayes factor, a minimum group membership threshold of five percent, and clinical interpretability. The result was a taxonomy of medication-taking behavior that is far more nuanced than a single adherence rate could ever convey.

The largest group, comprising 52.27 percent of members, was labeled consistent adherent, maintaining high medication coverage throughout follow-up. The remaining members scattered across four suboptimal pathways. The delayed decliner group, 13.53 percent of the cohort, held steady for roughly three months before sliding. The consistent decliner group, 12.85 percent, showed a steady reduction from the outset. The fluctuating adherent group, 11.14 percent, cycled through declines and partial recoveries, a pattern that may reflect intermittent access barriers or wavering motivation. Most concerning was the rapid discontinuer group, 10.21 percent, who abandoned therapy by the second month and never returned, a trajectory often associated with early adverse effects such as nausea and gastrointestinal distress, or with immediate obstacles to refilling prescriptions.

Multinomial logistic regression, using the consistent adherent group as the reference, illuminated who was most at risk of falling off course. Members who initiated therapy in July through December 2023 had more than twice the odds of becoming rapid discontinuers compared with 2025 initiators, an odds ratio of 2.10, likely reflecting the chaos of the shortage era. Age mattered profoundly: members aged 40 to 64 had significantly lower odds of suboptimal trajectory membership than those aged 18 to 39, perhaps because younger patients perceive less disease severity, have shallower roots in the healthcare system, and face fewer obesity-related complications that motivate sustained treatment. Black members had higher odds of belonging to the rapid discontinuer and fluctuating adherent groups than white members, a disparity the authors attribute to structural and socioeconomic barriers rather than race itself. Enrollment in a managed care organization was protective, cutting the odds of rapid discontinuation by roughly a third, presumably because care coordination, medication management programs, and proactive outreach help keep patients engaged in ways that fragmented fee-for-service coverage cannot.

Clinical characteristics painted a more complicated picture. Type 2 diabetes and cardiovascular comorbidities were associated with higher odds of suboptimal trajectories, possibly reflecting greater clinical complexity and competing therapeutic priorities that crowd out obesity treatment. Hypertension, paradoxically, was protective, reducing the odds of delayed decliner membership. Sex showed no significant association, a departure from prior studies, though the authors note their cohort was so overwhelmingly female, reaching 93 percent of initiators in early 2025, that detecting sex differences may have been statistically impractical. Sleep apnea, fatty liver disease, hyperlipidemia, kidney conditions, and depression were not significantly linked to trajectory membership.

The policy implications are considerable. As of January 2026, only 13 state Medicaid programs covered at least one GLP-1 receptor agonist approved for weight management, and several have since withdrawn or restricted coverage. Coverage alone, the Mississippi experience suggests, is insufficient to guarantee therapeutic engagement. Fewer than five percent of initiators in the program received counseling services before starting therapy, a strikingly low uptake given that discontinuation is consistently associated with rapid weight regain and loss of cardiometabolic benefit. The authors argue for expanded care management, patient education, behavioral counseling, and side effect support, alongside robust lifestyle programs that can mitigate regain among those who stop the drugs. The temporal improvement across cohorts also offers a hopeful signal: fixing structural access barriers, as the shortage resolution did, produces measurable gains in continuity. For the other states weighing coverage decisions, Mississippi’s data provide a rare, unvarnished look at what happens when expensive, effective medications meet a high-need population, and a reminder that the hardest part of obesity pharmacotherapy may begin not at the first injection, but at the second and every one after.

Subject of Research: Real-world adherence and persistence to GLP-1 receptor agonist anti-obesity medications among Medicaid enrollees

Article Title: Real-World Adherence Patterns and Predictors of GLP-1 Receptor Agonist Use for Obesity Management in a Medicaid Population

Article References: Bazzazzadehgan, S., Pittman, E., Lin, L.-Y., Qi, J., Ly-Ha, A., Smith, D., Kirby, T., Vest, T. A., Bentley, J. P., & Bhattacharya, K. (2026). Real-World Adherence Patterns and Predictors of GLP-1 Receptor Agonist Use for Obesity Management in a Medicaid Population. Advances in Therapy. https://doi.org/10.1007/s12325-026-03806-x

Image Credits: AI Generated

DOI: 10.1007/s12325-026-03806-x

Keywords: GLP-1 receptor agonists, anti-obesity medications, Medicaid, medication adherence, persistence, group-based trajectory modeling, obesity, health disparities, Mississippi, drug shortage, proportion of days covered, health policy