Dapagliflozin’s Cost-effectiveness ‘Intermediate’ for HFrEF

Although recent trial results have established the sodium glucose cotransporter 2 inhibitors dapagliflozin and empagliflozin as a key new part of the recommended multidrug treatment regimen for patients with heart failure with reduced ejection fraction, the current U.S. cost for dapagliflozin means it has merely “intermediate” value when it comes to cost-effectiveness.

A typical regimen with dapagliflozin to treat patients with heart failure with reduced ejection fraction (HFrEF) costs about $474/month or roughly $5,700/year based on Medicare pricing. After factoring in the incremental clinical benefits producing by dapagliflozin seen in the DAPA-HF pivotal trial that helped establish its role, this price produces a cost per quality-adjusted life-year (QALY) gain of about $84,000, which puts dapagliflozin squarely in the intermediate range for value set in 2014 by a task force of the American College of Cardiology and the American Heart Association.

This cost-effectiveness value depends largely on the proven efficacy of dapagliflozin (Farxiga) for decreasing the incidence of cardiovascular death among treated patients with HFrEF, and puts the drug’s value roughly on par with another agent recently approved to treat such patients, sacubitril/valsartan (Entresto), which carries a cost-effectiveness value of about $45,000/QALY.

The U.S. cost per QALY for dapagliflozin treatment of patients with HFrEF dwarfed the value numbers calculated for several other countries that were generally one-tenth this size. This disparity stemmed from both the relatively high price for dapagliflozin in the U.S. compared with other countries — nearly tenfold higher — and relatively higher costs for all types of U.S. medical care, Justin T. Parizo, MD, and coauthors said in a recent report. But the cost, and hence the cost per QALY, of dapagliflozin may soon drop because certain patents on the drug expired in October 2020, added Parizo, a cardiologist at Stanford (Calif.) University, and associates. Despite the expired patents, as of June 2021 no generic form of dapagliflozin appeared available for U.S. sale.

Medicare Patients Pay About $1,630/Year Out-of-Pocket

“A key caveat” to this finding for dapagliflozin is that being cost-effective “is not by itself a mandate for routine clinical use,” Derek S. Chew, MD, and Daniel B. Mark, MD, said in an editorial that accompanied the report.

A major stumbling block for widespread U.S. prescribing of dapagliflozin to patients with HFrEF is its overall price tag for U.S. patients, estimated at $12 billion/year, as well as an out-of-pocket annual cost for individual Medicare patients of roughly $1,630/year. Adding this out-of-pocket cost to the copay for sacubitril/valsartan and two other much less expensive drug classes that together form the current mainstay, quadruple-drug regimen for HFrEF treatment means a potential annual cost paid by each Medicare patient of about $3,000, wrote Chew, a cardiologist, and Mark, a cardiologist and professor, both at Duke University, Durham, N.C.

They cited the precedent of the “unexpectedly slow” and “anemic” uptake of sacubitril/valsartan since its U.S. approval in 2015, a cost-effective agent with “comparable clinical effectiveness” to dapagliflozin. “Even with full inclusion [of sacubitril/valsartan] on formularies and elimination of preapproval requirements, use remains very low, and patient-borne out-of-pocket costs may be a key factor,” wrote Chew and Mark. They cited a results from a study that showed abandonment of new prescriptions at retail U.S. pharmacies spiked to a 60% rate when out-of-pocket cost exceeded $500.

More Than What Patients “Can Afford or Are Willing to Spend”

The estimated $3,000-plus total out-of-pocket cost currently borne by some Medicare beneficiaries with HFrEF who have to shell out for both sacubitril/valsartan and dapagliflozin “appears to substantially exceed what many patients with heart failure can afford or are willing to spend,” wrote Chew and Mark.

Parizo and coauthors developed their cost-effectiveness model for dapagliflozin in treating HFrEF using primarily data collected in the DAPA-HF trial, which proved the efficacy of the drug for reducing cardiovascular deaths or acute heart failure events that led to hospitalization or intravenous outpatient treatment in more than 4,700 randomized patients with HFrEF. The trial enrolled roughly similar numbers of patients with or without type 2 diabetes.

The model showed an overall incremental cost-effectiveness ratio of $83,650/QALY, which was about the same regardless of whether patients also had type 2 diabetes. On a more granular level, the cost-effectiveness value estimate was $78,483/QALY in patients with mild health-status impairment due to their heart failure, and $97,608/QALY in patients with moderate impairment, a finding that underscores the importance of starting dapagliflozin treatment early in the course of HFrEF when disease effects are less severe.

The analysis could not address value in patients with more advanced heart failure and in New York Heart Association functional class IV because fewer than 1% of patients in DAPA-HF were in this category.

Drug cost was a major determinant of cost-effectiveness. A 50% drop in cost from the Medicare benchmark of $473.64/month resulted in an incremental cost-effectiveness ratio of about $45,000/QALY (putting it into the high-value category based on the 2014 ACC/AHA formula), while a 50% rise in price yielded a value of nearly $123,000/QALY (still in the intermediate range, which spans from $50,000/QALY to $150,000/QALY).

No other cost parameters had a meaningful effect on the cost-effectiveness calculation. The analyses also showed that using the basic cost assumptions, treatment with dapagliflozin needs to persist and remain effective for at least 44 months to produce a cost per QALY that’s less than $150,000. The authors stressed that their analysis considered heart failure effects and did not account for added benefit from treatment with dapagliflozin on preservation of renal function.

While it’s indisputable that treatment with dapagliflozin decreases health care costs by, for example, reducing hospitalizations for heart failure, each hospitalization costs just over $12,000, according to the assumptions made by Parizo and coauthors. But given dapagliflozin’s impact on this outcome, this cost saving translates into about $500/patient during 18 months on treatment (the median duration of treatment in DAPA-HF), which means the savings barely counterbalances the current cost of dapagliflozin treatment for 1 month, noted Chew and Mark.

The DAPA-HF trial was sponsored by AstraZeneca, the company that markets dapagliflozin (Farxiga). Parizo had no disclosures and none of his coauthors had a relationship with AstraZeneca. Chew had no disclosures. Mark has received research grants from HeartFlow, Mayo Clinic, and Merck.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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