Impact of discounting in pharmacoeconomic modeling. A case study

Abstract

Discounting adjusts future costs and benefits in terms of their present value. The purpose of this study was to present the effect of discounting on Markov model prepared for the evaluation of the different antihypertensive treatments in Serbia. The Markov model consisting of eight states with the cycle length of six months was constructed. Comparator strategies were diuretic, beta blocker, calcium channel blocker and ACE inhibitors. All therapeutic strategies were compared with strategy "no intervention". Complications of hypertension (acute myocardial infraction, angina pectoris or stroke alone or in combinations) and total mortality were observed as outcomes. Time horizon of the study was lifetime of the patient or 100 years old, due to assumption that 99% of the cohort would die at that age. Analyses were performed from the third-party payer perspective. Annual discount rate of 5% was applied at all future costs and effects. Undiscounted results showed that patients who started treatment with a beta blocker had the highest life expectancy (49.00 QALY) and being the most cost-effective strategy (ICER = €46.63/QALY compared to no intervention). In the case of discounting the highest gain in the QALY had patients who were on beta blocker, 23.7 QALY. After the discounting cost-effective strategies were ACE inhibitor (ICER = €253.08/QALY compared to no intervention) and diuretic (ICER = €262.54/QALY compared to no intervention). The results of the study showed that the discounting could change the choice of cost-effective therapeutic strategy.