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