This cost-effectiveness analysis of a hypothetical cohort of Medicare beneficiaries demonstrates that compared with the current Part D drug benefit, the elimination of patient cost sharing for medications commonly prescribed to post-MI patients would both improve health and save money from the societal perspective. The magnitude of observed changes in health outcomes is large and substantially greater than that observed for other interventions widely used to improve post-MI outcomes such as dual antiplatelet therapy39
or early invasive risk stratification strategies.40
In addition, average cost reductions of $2500 per beneficiary would save society $1 billion for the ≈400 000 Medicare beneficiaries who have an acute MI every year (Hospital Intervention QIOSC based on Center for Medicare and Medicaid Services Discharge Claims Data Warehouse, personal communication, 2006, Oklahoma City, OK).
As such, our results strongly support the hypothesis that post-MI Medicare beneficiaries should receive statins, ACEIs/ARBs, and β-blockers without cost sharing and emphasize the urgent need for prospective clinical studies to confirm the effectiveness of this approach.
Our results were robust to many of the model assumptions. In particular, full coverage will dominate current coverage (ie, be both more effective and less costly) as long as more patients remain adherent to therapy than would have otherwise. In addition, although the analysis conducted from the perspective of Medicare did not indicate that full coverage would be cost saving, the incremental cost-effectiveness ratio of this strategy ($7182/QALY) is well below accepted thresholds for commonly used therapies.
The present analysis extends our prior work that evaluated the cost-effectiveness of providing 3 years of full coverage for combination pharmacotherapy to post-MI patients from the perspective of a typical commercial insurance company.15
In contrast to our previous results, full coverage was cost-effective but not cost saving from the Medicare perspective. There are several reasons for this difference: We used Medicare hospitalization reimbursement rates, which are lower than those paid by commercial insurers; we assumed that the amount of patient cost sharing for Part D beneficiaries is more than that for privately insured patients (63% versus 32% of drug costs); we assumed a smaller increase in adherence from full coverage than we did previously; and we considered a much longer time frame. Repeating this analysis using event costs similar to those used in previous analyses of full coverage15,41
resulted in full coverage being a dominant, cost-saving strategy. Lowering the average cost of a 1-year supply of 1 medication to $90 also makes full coverage cost saving from the Medicare perspective. This scenario is easily plausible given the availability of $4/mo ($48/y) generic medications at many retail pharmacies and the likelihood that Medicare prescription drug plans receive even greater discounts than those available to individual consumers.
Overall, our results help make the “business case” for Medicare to expand current levels of prescription drug coverage provided under the Part D program for post-MI secondary prevention therapies. There are many interventions designed to improve medication adherence,42
although those shown to be effective are resource intensive. In contrast, the selective reduction of cost sharing for medications of proven efficacy is administratively less complex and may be scaled to large numbers of patients. Moreover, there is precedent in Medicare for selectively offering benefits to patients with particular conditions (ie, individuals <65 years of age with end-stage renal or Lou Gehrig’s disease) and for particular medications (eg, injectable medications under Part B). The challenge with this adherence improvement strategy, and value-based insurance designs more generally,43
is identifying the medications and associated health conditions for which reducing copayments for prescription drugs will simultaneously improve health and reduce costs, as we have demonstrated for post-MI secondary prevention medications. ACEIs for diabetics,41
statins for high-risk primary and secondary prevention of CHD,44
and antirejection drugs for kidney transplant recipients45
all have promise in this regard. Accordingly, large employers and insurers have begun experimenting with the selective reduction of copayments for patients with a variety of conditions and have found favorable short-term economic returns.46,47
Our analysis is subject to several limitations. First, our results are based on a cost-effectiveness model that was built using estimates from the literature rather than the results of a prospectively conducted trial designed to compare full and current levels of prescription drug coverage. Moreover, because many of our model parameters such as the true benefit of combination pharmacotherapy or the effect of completely removing out-of-pocket costs on medication adherence have not been rigorously tested, our results should be considered hypothesis generating. It is reassuring that our findings were robust to our assumptions. For example, we found full coverage to be cost saving as long as combination pharmacotherapy reduced the relative risk of reinfarction by at least 45%. By way of comparison, this is less than the relative risk reduction over placebo expected from statin therapy alone, without considering the other constituents of combination therapy based on conservative estimates of the trial literature. 2
Nevertheless, a high-quality trial in actual practice is needed to validate the results of our analysis.
Second, we did not evaluate the impact of cost-sharing reductions for other commonly used post-MI medications such as clopidogrel and higher-potency statins. Although these drugs provide incremental benefit over the regimen we evaluated, they do so with significant increases in expense, and their long-term role remains economically undefined. On the basis of our previous analysis,15
providing these medications in the short run appears to be an economically viable strategy. Finally, we did not evaluate the impact of providing insurance coverage to those currently without insurance. Although doing so would result in significant increases in drug costs faced by insurers, it also would likely induce a significantly greater number of currently nonadherent patients to begin using these drugs than among the currently insured population we assessed.