Impacts of Annual Wage on Insulin Adherence in Diabetes
Author(s)
Brenna Brady, PhD, Robert Fowler, MS, Liisa Palmer, PhD;
Merative, Ann Arbor, MI, USA
Merative, Ann Arbor, MI, USA
OBJECTIVES: Insulin costs pose a treatment barrier for patients with diabetes. In 2023 the Centers for Medicare and Medicaid Services capped out-of-pocket insulin costs at $35 to help reduce access barriers; similar cost limiting programs were also instituted by several insulin producers. This analysis examined insulin adherence based on patient wage both prior and following insulin access programs.
METHODS: Samples of adult patients with type 1 or type 2 diabetes (T1D, T2D) using insulin with continuous medical and pharmacy eligibility were selected in the MerativeTM MarketScan® Commercial Database for the 2019 and 2023 calendar years. Eight subgroups (<$30k, $30-<$50k, $50-<$70k, $70k-<$90k, $90k-<$110k, $110k-<$150k, $150k-<$200k, and ≥$200k) were defined using annual wage data from MarketScan Databases and insulin adherence was calculated as proportion of days covered (PDC).
RESULTS: A total of 14,887 and 11,109 patients qualified for the 2019 and 2023 samples respectively. Mean±SD PDC ranged from 0.75±0.20-0.78±0.19 in 2019 and 0.71±0.23-0.78±0.18 in 2023; the $30-<$50k group had the lowest PDC in both samples, while the ≥$200k group had the highest. The proportion of adherent (PDC ≥0.80) patients generally increased with wage, while the proportion of patients with a diabetes-related inpatient or emergency visit decreased. Trends for increasing adherence with higher wage were largely driven by the two-thirds of patients with T2D. Despite institution of cost reduction programs, adherence decreased in the T2D sample in all groups except the <$30k group, which saw a 5.5% increase, from 2019 to 2023. Conversely, adherence universally increased in the T1D sample from 2019 to 2023 with the greatest difference (11.7%) observed in the <$30k group.
CONCLUSIONS: Results from this study demonstrate links between medication costs and adherence while adjusting for wage and highlight the importance of medication affordability. This early assessment also suggests positive impacts of programs to control insulin costs, especially for low income and T1D patients.
METHODS: Samples of adult patients with type 1 or type 2 diabetes (T1D, T2D) using insulin with continuous medical and pharmacy eligibility were selected in the MerativeTM MarketScan® Commercial Database for the 2019 and 2023 calendar years. Eight subgroups (<$30k, $30-<$50k, $50-<$70k, $70k-<$90k, $90k-<$110k, $110k-<$150k, $150k-<$200k, and ≥$200k) were defined using annual wage data from MarketScan Databases and insulin adherence was calculated as proportion of days covered (PDC).
RESULTS: A total of 14,887 and 11,109 patients qualified for the 2019 and 2023 samples respectively. Mean±SD PDC ranged from 0.75±0.20-0.78±0.19 in 2019 and 0.71±0.23-0.78±0.18 in 2023; the $30-<$50k group had the lowest PDC in both samples, while the ≥$200k group had the highest. The proportion of adherent (PDC ≥0.80) patients generally increased with wage, while the proportion of patients with a diabetes-related inpatient or emergency visit decreased. Trends for increasing adherence with higher wage were largely driven by the two-thirds of patients with T2D. Despite institution of cost reduction programs, adherence decreased in the T2D sample in all groups except the <$30k group, which saw a 5.5% increase, from 2019 to 2023. Conversely, adherence universally increased in the T1D sample from 2019 to 2023 with the greatest difference (11.7%) observed in the <$30k group.
CONCLUSIONS: Results from this study demonstrate links between medication costs and adherence while adjusting for wage and highlight the importance of medication affordability. This early assessment also suggests positive impacts of programs to control insulin costs, especially for low income and T1D patients.
Conference/Value in Health Info
2025-05, ISPOR 2025, Montréal, Quebec, CA
Value in Health, Volume 28, Issue S1
Code
PCR6
Topic
Patient-Centered Research
Topic Subcategory
Adherence, Persistence, & Compliance
Disease
SDC: Diabetes/Endocrine/Metabolic Disorders (including obesity)