Antidiabetes Drug Costs Keep Patients Away

Mitchel L. Zoler, PhD

June 06, 2022

NEW ORLEANS – High out-of-pocket costs for medications used by patients with diabetes are tied to reduced use of these drugs and ultimately worse clinical outcomes, according to findings from two separate studies.

One study looked at the insurance records of more than 70,000 U.S. patients with type 2 diabetes and established cardiovascular disease who were already on metformin. The findings showed that, after adjustment for confounders, the quartile of patients with the highest out-of-pocket cost for an agent from the sodium-glucose cotransporter 2 (SGLT2)–inhibitor class filled a prescription for one of these drugs a significant 21% less often than did patients from the quartile with the lowest personal expense, after adjustment for a variety of potential confounding factors, reported Jing Luo, MD, at the annual scientific sessions of the American Diabetes Association.

A similar analysis run by Luo and his associates looking at glucagonlike peptide-1 (GLP-1) receptor agonists showed that the quartile of patients who had to pay the most for one of those drugs had an adjusted 12% lower rate of filling a prescription, compared with those with the lowest out-of-pocket expense, a difference that fell just short of significance.

"If we consistently see that high drug costs affect use of highly effective medications in patients with type 2 diabetes and risk factors, it's quite problematic because it's not just a matter of money, but it also makes a difference in the patient's quality of care," Luo said in an interview.

Prevention Drug Lists Can Help

Consistency turned up in a second report at the same ADA session that retrospectively reviewed data collected during 2004-2017 by a single large U.S. health insurer to identify 3,315 matched pairs of children and adults with diabetes who all had high-deductible health plans for their medical insurance, along with an associated health savings account.

One set of patients in each matched pair began to receive, at some point during follow-up, coverage with a prevention drug list (PDL; also called a formulary) that provided them with a variety of specified agents at no charge. They included oral antidiabetes agents, insulin, antihypertensives, and lipid-lowering drugs. The other half of the matched pairs of patients received no PDL coverage and had copays for their antidiabetes medications.

The findings showed that the rates of out-of-pocket costs for antidiabetes drugs, antidiabetic medications used, and acute diabetes complications all tracked extremely closely between the matched pairs before half of them started to receive their PDL coverage. However, after PDL coverage kicked in, out of pocket costs dropped by 32% for the people with PDL coverage, compared with those who did not receive this coverage. Oral antidiabetes medication use rose modestly, but acute diabetes complications "declined substantially," with a 14% relative reduction overall in those with PDL coverage, compared with those without, reported J. Franklin Wharam, MBBCh, a professor and health policy researcher at Duke University in Durham, N.C. In the roughly half of the study cohort who fell into a low-income category based on where they lived, the rate of excess acute diabetes complications was 23% higher for those without a PDL, compared with those who had that coverage.

PDL coverage linked with "large reductions in acute, preventable diabetes complications," concluded Wharam. "Policy makers and employers should incentivize PDL uptake among low-income patients with diabetes."

Newer, More Effective Drugs Cost a Lot

"The more comorbidities that patients have, the greater is the strength of the evidence for using newer antidiabetes drugs that are more expensive," but that would mean spending much more on this part of patient care, noted Luo, an internal medicine physician and researcher at the University of Pittsburgh. "It will cost a lot of money, and I'm not sure what the solution is. It's a huge conundrum."

About 30 million Americans have type 2 diabetes. If every one of them went on an SGLT2 inhibitor, or went on an SGLT2 inhibitor plus a GLP-1 receptor agonist, "it would bankrupt the U.S. health care system, so we can't do that," commented Sylvio E. Inzucchi, MD, in an interview. "The only thing holding this back is cost. We target these drugs to the patients most apt to benefit from them. If they were generic they would be used much more widely," noted Inzucchi, professor and clinical chief of endocrinology at Yale University in New Haven, Conn.

The study run by Luo and his associates retrospectively reviewed data from 72,743 U.S. adults included in the Optum Clinformatics database during December 2017–December 2019. All included patients had type 2 diabetes, received metformin monotherapy, and had established atherosclerotic cardiovascular disease. They averaged 72 years of age, 56% were men, and 88% were on a Medicare Advantage plan, while the remainder had commercial insurance. Their average hemoglobin A1c level was 6.8%.

People in the quartile with the lowest copays spent an average of about $20/month for either an SGLT2 inhibitor or a GLP-1 receptor agonist. Those in the quartile with the highest copays spent roughly $100/month for agents from each of these two classes. The analysis followed patients for a median of 914 days.

In addition to finding disparate rates of drug use between these two quartiles, the analysis also showed that higher copays linked with longer times to initially fill prescriptions for these drugs. But while those with higher copays took longer to start both classes than did those with the smallest copays, even those with the lowest out-of-pocket costs averaged about a year to initiate treatment.

Luo attributed this delay to other factors besides costs to patients, such as clinicians prescribing other classes of second-line oral antidiabetes agents, clinical inertia, and lack of awareness by clinicians of the special benefits of SGLT2 inhibitors and GLP-1 receptor antagonists for patients with type 2 diabetes and cardiovascular disease.

"A lot of clinical and social factors drive medication use," not just out-of-pocket cost, he explained.

Luo is a consultant to Alosa Health. Wharam had no disclosures. Inzucchi is an adviser to Abbott Diagnostics, Esperion Therapeutics, and vTv Therapeutics, a consultant to Merck and Pfizer, and has other relationships with AstraZeneca, Boehringer Ingelheim, Lexicon, and Novo Nordisk.

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