The Potential Impact of the Supplemental Nutrition Assistance Program (SNAP) on Adherence to Antihypertensive Medications

Background: Nonadherence to antihypertensive medications (AHMs) is associated with higher risks of death, heart diseases and stroke. Food insecurity (FI) is a risk factor of medication underuse among hypertension patients. The Supplemental Nutrition Assistance Program (SNAP) is an effective federal nutrition assistance program for reducing FI. However, the impact of SNAP as a potential intervention for improving adherence to AHMs has not been investigated.

Objectives: To assess the associations between receipt of SNAP benefits and nonadherence to AHM.

Methods: AHM users were identified from the Medical Expenditure Panel Survey (MEPS) data, 2016-2017; a national longitudinal survey on verified self-reported prescribed medication use, healthcare access measures, etc. Our analysis focused on only the 2016-2017 data because receipt of SNAP in the past 12 months and past 30-days FI status were assessed through standard questionnaire during only this data cycle. SNAP, FI status and several covariates (demographic, health status and access to healthcare factors) were measured from the 2016 data. We then measured annual AHM medication refill adherence (MRA) from the 2017 data as the total days' supply divided by 365 days for each AHM class. Overall MRA was obtained as the average of MRAs for participants who used more than one AHM. Patients were considered to be nonadherent if their overall MRA was < 80%. Inverse probability of treatment (IPT) weighting technique was used to control for measured confounding effects on the association between SNAP and AHM nonadherence; FI was not included in the propensity score models. We used logistic regression models, weighted by the product of the computed IPT-weights and MEPS survey weights, to estimate the average treatment effects (ATE) of SNAP on nonadherence, overall and stratified by FI status.

Results: Of the 6692 AHM users, 1203 (18%) received SNAP while 5489 (82%) did not. SNAP was not associated with AHM nonadherence in the overall AHM user population. However, among the FI AHM user population (n=1338), Receipt of SNAP benefits significantly reduced the risk of AHM nonadherence by nearly 11% (ATE=-10.5%, 95%CI: -18.5% to -2.4%).

Conclusions: If confirmed in a randomized control trial, a social intervention program such as SNAP could potentially be leveraged as an inexpensive intervention to improve AHM adherence especially among hypertension patients who are experiencing food insecurity.