HIV medication adherence follows SNAP payment timing, study finds

Adherence to daily HIV medication among low-income patients follows with the monthly rhythm of Supplemental Nutrition Assistance Program (SNAP) benefits, rising after payments go out and decreasing as the next payment approaches, according to a study published in JAMA Network Open.

The researchers designed the study to test scarcity theory, which holds that financial hardship imposes a cognitive burden that can crowd out health-protective behaviors like taking medication on schedule. Much of the existing evidence for that theory comes from artificial lab exposures rather than objectively measured, real-world outcomes.

Researchers led by Aaron Richterman, M.D., M.P.H., of the University of Pennsylvania, enrolled 54 Philadelphia-area SNAP recipients with HIV who reported missing 2 or more antiretroviral therapy (ART) doses in the past 30 days. Participants were recruited from counties where SNAP disbursement dates are randomly assigned by case number to one of the first 10 business days of the month. This allowed researchers to treat payment timing as effectively random. The average age of participants was 55, and nearly two-thirds had income below the federal poverty level.

On average, patients received $291 in SNAP benefits monthly. Participants were followed for four months, their daily ART adherence tracked using electronic pill bottle caps.

Mean ART adherence across the cohort was 66.9%, with adherence climbing for approximately 20 days after a SNAP payment before declining. Adherence fell by approximately 1% per day. There was a peak-to-trough decline of 11.9% percentage points between SNAP benefit cycles.

"By leveraging the randomized timing of SNAP disbursement, this study is among the first to provide evidence that short-term scarcity relief may affect daily health behavior," Richetrman and his team write in the study. "Limitations include small sample size and focus on people with HIV in one city."

The authors describe the pattern as consistent with habit formation, in which automaticity builds as financial scarcity eases and erodes as it returns.

The findings come as SNAP enrollment is shrinking nationally. New work requirements, part of a 2025 budget law, took effect in February, and USDA data show SNAP participation fell by about 5.3 million people, or roughly 13%, between September 2025 and April 2026.

The study's authors point directly to that shrinking safety net, writing that with upcoming SNAP policy changes expected to reduce participation, the findings underscore the importance of poverty alleviation for chronic disease outcomes.

For payers, the findings add to a growing evidence base linking food insecurity intervention to medication-taking behavior, a connection several health plans have tried to act on through food-as-medicine benefits, produce prescriptions, and social needs screening built into HIV and chronic disease case management. A predictable, cyclical dip in adherence tied to benefit timing, rather than a random or one-time lapse, could give plans a more specific window for outreach, refill reminders, or supplemental support near the end of a member's SNAP cycle.

“Medication adherence is a primary determinant of chronic disease outcomes yet remains suboptimal, particularly among low-income populations,” the authors write. "With upcoming SNAP policy changes expected to reduce participation, these results underscore the importance of poverty alleviation for chronic disease outcomes.”