In a study recently published in JAMA Network Open , researchers looked at the relationship between Colorado’s $100 out-of-pocket limit and out-of-pocket spending, medication adherence, and health care utilization for diabetes-related complications.
Study: Changes in health outcomes among people with type 1 diabetes after state-level insulin copayment caps are implemented. Image credit: Pixel-Shot/Shutterstock.com
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Diabetes is the most costly chronic disease in the United States, and people with type 1 diabetes require lifelong insulin therapy. Although insulin costs have remained stable despite manufacturer price cuts, list prices are 10 times higher than in most other countries. This financial burden has led 25 states and the District of Columbia to pass legislation reducing insulin copayments for state-managed private health insurance plans. Colorado was the first state to impose insulin copayment caps, but empirical research on the relationship between these policies and health outcomes is lacking.
About the Research
In this study, researchers evaluated the impact of Colorado's Insulin Affordability Program's statewide insulin copayment cap policy of $100 on out-of-pocket payments, treatment adherence, and health care utilization for diabetes complications.
Approximately 38 million people have diabetes, and more than 7 million use one or more types of insulin.
Study population included enrollment in state-regulated health insurance plans compliant with the insulin copayment cap law that went into effect on January 1, 2020. Primary outcome measures were adherence to basal and bolus insulin, out-of-pocket payments, and health care utilization for diabetes-related complications.
The researchers used percentage-of-days-covered measures to assess adherence to basal and bolus treatments, out-of-pocket costs based on 30-day prescription costs, and identified health service utilization for diabetes-related complications using principal diagnosis codes from medical claims data.
Researchers analyzed nonelderly individuals with insulin-dependent diabetes using the Colorado All-Payer Claims Database (CO APCD) from January 2019 to December 2020. Participants were under 65 years of age and enrolled in the same health insurance plan between January 2018 and December 2020.
The researchers identified medical claims for diabetes-related complications (such as hyperglycemia, hypoglycemia, ketoacidosis, tissue or skin infections, retinopathy, cardiovascular disease, and kidney problems) using primary diagnosis codes aggregated at the person-month level. The researchers monitored participants for two years (January 2019 to December 2020).
The post-policy implementation phase lasted from January to December 2020. The researchers used difference-in-differences regression to examine changes in pre- and post-policy outcomes among individuals with continuous enrollment in nonstate and state-regulated insurance plans. They conducted subgroup analyses according to individuals' pre-policy expenditures (low: never spent $100.0 out of pocket; high: paid $100 out of pocket 1 or more times).
The researchers adjusted for age, sex, region of residence, comorbidities, insurance plan type, and non-diabetes-related medical claims and used generalized linear regression to analyze data from June 2023 to May 2024. To support their findings, they conducted sensitivity analyses excluding the two months before and after the policy implementation, as well as falsification tests by repeating the regressions using non-insulin prescriptions as study outcomes.
result
The study included 1,629 patients with insulin-dependent diabetes, of whom 924 were men (57%), 540 had comorbidities (33%), and the mean age was 41 years. Of the participants, 123 (7.60%) were enrolled in a HDHP, and 21% had medical claims for diabetes-related complications. One in four insulin users spent more than $100 out of pocket on prescription drugs. Initially, the average copayment for a month's supply of basal insulin was $68 and for bolus insulin was $88. Treatment adherence was 63% for basal insulin and 65% for bolus insulin.
The copayment cap policy reduced copayments for basal insulin by $17 and bolus insulin by $12, and improved adherence by 3.20% and 3.30%, respectively. The change in adherence was associated with an increase in high spenders before the policy was implemented (basal 9.9%, bolus 13%). The program reduced claims for type 1 diabetes-related complications by an average of 30% per person per month in the high spender group. Sensitivity analyses showed similar results, and falsification analyses using non-insulin formulations showed statistically negligible results, validating the study findings.
Out-of-pocket payments for bolus and basal insulin were highest in January and February, when participants reached their maximum or deductible amounts, and lowest in the past 3 months. However, out-of-pocket payments decreased in January 2020, the month the policy was implemented, reducing seasonal fluctuations, especially for basal insulin. The reductions were more severe among those who paid more than $100 out-of-pocket at least once before the policy was implemented.
Conclusion
Studies have shown that enforcing insulin restrictions in people with type 1 diabetes reduces out-of-pocket spending and improves treatment adherence and health outcomes. However, these benefits primarily benefited individuals whose pre-policy spending levels were above the cap. The level of the cap determines short-term outcomes.
The findings support policymakers' goals of making insulin more affordable and improving access to and adherence to treatment for insulin-dependent individuals. In January 2022, the law was changed to limit monthly copayments to $100 and provide emergency prescriptions for eligible individuals for a fee of $35 or less within 12 months.
