IMPACT OF STATE-LEVEL INSULIN OUT-OF-POCKET SPENDING CAPS ON UTILIZATION OF PREFERRED NON-INSULIN MEDICATIONS FOR TYPE 2 DIABETES
Author(s)
Michael J. DiStefano, PhD1, Jennifer M. Trujillo, PharmD1, Kelly E. Anderson, PhD2;
1University of Colorado Anschutz Medical Campus, Aurora, CO, USA, 2Mass General Brigham/Harvard Medical School, Cambridge, MA, USA
1University of Colorado Anschutz Medical Campus, Aurora, CO, USA, 2Mass General Brigham/Harvard Medical School, Cambridge, MA, USA
OBJECTIVES: To investigate the effect of state-level monthly insulin out-of-pocket (OOP) spending caps on changes in the use of preferred non-insulin medications for people with type 2 diabetes (T2D)
METHODS: This was a retrospective cohort study employing a time-varying difference-in-differences framework. The intervention was implementation of a state-level monthly insulin out-of-pocket spending cap from 2020-2022. The dichotomous outcome was calculated at the patient-quarter level and represented whether enrollees had a medication possession ratio (MPR) of at least 80% for a preferred non-insulin T2D medication. Preferred medications included GLP-1 receptor agonists and SGLT2 inhibitors. We used a 25% random sample from IQVIA’s PharMetrics Plus for Academics covering all 50 states and Washington D.C. from 2018-2022.
RESULTS: The primary analysis including all 20 treated states found that spending caps were associated with a non-significant 1.8% increase in enrollees with at least an 80% MPR for a preferred non-insulin medication (p=0.302). Limiting the post-treatment window to the first year showed that caps were associated with a statistically significant 2.2% increase (p=0.005). In a secondary analysis focused on states with the most generous caps ($40 or less), caps were associated with a non-significant 1.4% increase in enrollees with at least an 80% MPR for a preferred non-insulin medication (p=0.738). Limiting the post-treatment window to the first year showed the most generous caps were associated with a statistically significant 3.7% increase (p=0.028). These effects were highly sensitive to study sample composition; excluding Texas from analysis resulted in a null effect over the first year post-implementation.
CONCLUSIONS: These findings add to the literature demonstrating little impact of insulin OOP spending caps on utilization of diabetes medications in commercial insurance markets. Future medication spending cap policies should target populations with elastic demand. Future research should consider the effects of spending caps beyond utilization, such as effects on mental health outcomes.
METHODS: This was a retrospective cohort study employing a time-varying difference-in-differences framework. The intervention was implementation of a state-level monthly insulin out-of-pocket spending cap from 2020-2022. The dichotomous outcome was calculated at the patient-quarter level and represented whether enrollees had a medication possession ratio (MPR) of at least 80% for a preferred non-insulin T2D medication. Preferred medications included GLP-1 receptor agonists and SGLT2 inhibitors. We used a 25% random sample from IQVIA’s PharMetrics Plus for Academics covering all 50 states and Washington D.C. from 2018-2022.
RESULTS: The primary analysis including all 20 treated states found that spending caps were associated with a non-significant 1.8% increase in enrollees with at least an 80% MPR for a preferred non-insulin medication (p=0.302). Limiting the post-treatment window to the first year showed that caps were associated with a statistically significant 2.2% increase (p=0.005). In a secondary analysis focused on states with the most generous caps ($40 or less), caps were associated with a non-significant 1.4% increase in enrollees with at least an 80% MPR for a preferred non-insulin medication (p=0.738). Limiting the post-treatment window to the first year showed the most generous caps were associated with a statistically significant 3.7% increase (p=0.028). These effects were highly sensitive to study sample composition; excluding Texas from analysis resulted in a null effect over the first year post-implementation.
CONCLUSIONS: These findings add to the literature demonstrating little impact of insulin OOP spending caps on utilization of diabetes medications in commercial insurance markets. Future medication spending cap policies should target populations with elastic demand. Future research should consider the effects of spending caps beyond utilization, such as effects on mental health outcomes.
Conference/Value in Health Info
2026-05, ISPOR 2026, Philadelphia, PA, USA
Value in Health, Volume 29, Issue S6
Code
HPR106
Topic
Health Policy & Regulatory
Topic Subcategory
Pricing Policy & Schemes, Reimbursement & Access Policy
Disease
SDC: Diabetes/Endocrine/Metabolic Disorders (including obesity)