Purpose: Vardenafil prescriptions for the management of erectile dysfunction are limited to four doses/month in the Veterans Health Administraton (VHA). However, greater quantities may be approved at the facility level on a case-by-case basis. The purpose of this analysis was to compare the cost-effectiveness of four, six and eight doses per month of vardenafil.
Method: A Markov model was used to estimate the incremental cost-effectiveness of no doses, four doses, six doses or eight doses of vardenafil per month in hypothetical cohorts of 60-year-old male Veterans with erectile dysfunction. Efficacy values for vardenafil were obtained from the published literature, and vardenafil costs were obtained from VHA pharmacy data. The analysis was conducted from a third-party payer perspective with a lifetime horizon; costs and effectiveness values were discounted at 3%/yr. Consistent with available data, we assumed there was no increased morbidity and mortality related to vardenafil use and no loss of treatment effect over time. In the base case analysis, four vardenafil doses/month improved utility by 0.01, with 2 more doses leading to an additional improvement of 0.01. Thereafter, rapidly diminishing improvements in utility were assumed.
Result: In the base case analysis, the cost per quality-adjusted life-year (QALY) gained for four doses of vardenafil per month compared with no therapy was $555. Six doses/month compared with four cost $8,313/QALY and eight doses/month compared with six cost $16,625/QALY gained. In one-way sensitivity analyses of six doses/month compared with four, variation of two parameters caused the incremental cost-effectiveness ratio (ICER) to cross a willingness-to-pay threshold of $20,000: when the increased utility associated with giving two additional doses per month decreased to ≤0.004 (baseline 0.01) and when the cost/dose increased to $5.00 (baseline $1.69). Increasing the vardenafil cost/dose to $15 raised the ICER of six doses/month to $73,671/QALY. In a probabilistic sensitivity analysis, 92.2% of 5000 iterations had an ICER <$50,000/QALY gained for six monthly doses, and 80.7% had an ICER <$20,000/QALY.
Conclusion: While four doses/month of vardenafil was by far the most cost-effective strategy, the use of six and eight doses/month also compares very favorably with accepted treatments for other medical conditions. The results were stable over a range of inputs and help to support the current VHA policy on the number of vardenafil doses dispensed per month.
Candidate for the Lee B. Lusted Student Prize Competition