A cost-utility analysis of phosphodiesterase type 5 inhibitors in the treatment of erectile dysfunction

Introduction Patent expiration for erectile dysfunction (ED) treatments like sildenafil means loss of exclusivity (LOE), and other manufacturers may bring generics to the market. This has resulted in price reductions, which influences the cost-effectiveness. In Norway, this development has led to a discussion on whether reimbursement should be granted. Cost-effectiveness analysis in this treatment area is scarce and more research is demanded. Objective The objective of this study was to assess the cost-effectiveness of three separate phosphodiesterase type 5 (PDE5) inhibitors in ED therapy in a Norwegian setting. Methods The cost-effectiveness was analyzed using two patient populations: (1) 55-year-old patients diagnosed with ED and with no specific underlying illness, and (2) 55-year-old patients diagnosed with ED and with diabetes as an underlying illness. Using a state-transition Markov model with a 10-year time horizon, a "no-treatment" option was compared with three treatment strategies: (1) treatment using 50/100 mg sildenafil; (2) treatment using 10/20 mg tadalafil; (3) treatment using 10 mg vardenafil. A societal perspective was applied. Results All PDE5 inhibitor treatment strategies were cost-effective compared to a "no-treatment" option, with cost per additional quality-adjusted life-year of less than euro15,000. With a willingness-to-pay threshold greater than euro13,500, sildenafil was estimated as the dominant treatment strategy. The probabilistic sensitivity analysis indicated robust results. However, as the expected value of information was considerable, the cost-effectiveness of conducting further research to reduce uncertainty should be considered. Treating a diabetic population was less cost-effective for all PDE5 inhibitors and was associated with greater uncertainty with regard to choosing the optimal strategy. Conclusions Sildenafil treatment of erectile dysfunction was a cost-effective alternative compared to tadalafil and vardenafil, as well as compared to a "no-treatment" option. Treating a diabetic population is less cost-effective for all PDE5 inhibitors and was associated with greater uncertainty.