Cost effectiveness of combination therapy. Based on a presentation by Daniel Hilleman, PharmD.

The ultimate economic goal of hypertension management is to balance costs and benefits, but defining these entities may be difficult. The overall cost of treating high blood pressure includes direct costs, such as drug acquisition, physician fees, laboratory and diagnostic tests, and management of side effects, as well as indirect costs, such as inadequate blood pressure control, noncompliance with therapy, and loss to follow up. Determining actual costs can be complicated. For example, medical charges are rarely paid as billed to third-party payers, and actual payments received for services are reimbursed at rates that vary from patient to patient and provider to provider. As difficult as determining treatment costs may be, quantifying the benefits and outcomes of treatment is probably even more difficult, especially because outcome can be classified as long term (with few available outcomes data on fixed-dose combinations), intermediate-term, and short-term. If blood pressure is considered a surrogate marker for mortality, it could be used in comparing the economic value of some antihypertensive agents. Cost-effectiveness studies evaluating hypertension treatment typically compare 2 or more alternatives, with the cost defined by 1 or more of 4 units of effectiveness. These units include: the money that needs to be spent to achieve the following: reach a specific mm-Hg reduction in blood pressure, reach a specific percentage reduction in blood pressure, treat a patient successfully to target blood pressure level, and treat a patient per quality-adjusted life-year gained. In studies evaluating fixed-dose combination therapy versus monotherapy in terms of response rates, costs per patient per year, and costs per successfully treated patient per year, combination therapy was found to be more effective in lowering blood pressure, but more expensive. However, the higher response rates seen with combination therapy either offset the added costs of managing patients with inadequately controlled hypertension or provided considerably better blood pressure control for only a few additional dollars per patient per year. Because prescription drug costs represent a significant percentage of the total costs of treating hypertension over time, several cost-containment interventions have been devised. These include formulary restriction, generic substitution, therapeutic interchange, prior authorization, and drug utilization.