PS2-32 VALUE OF ADDITION OF HPV VACCINATION TO ANAL PRECANCEROUS LESION TREATMENT IN OLDER MSM—DO WE NEED FURTHER EVIDENCE?

Purpose: Observational studies have shown that quadrivalent human papillomavirus (qHPV) vaccination of 27 years or older HIV-negative men who have sex with men (MSM) who were treated for initial high-grade squamous intraepithelial lesion (HSIL)—anal precancerous lesion—reduces the risk of recurrent HSIL. Our objective was to explore the value for future research on qHPV vaccination in 27 years or older MSM treated for initial HSIL. 

Method: We created two separate Markov models for HIV-positive and HIV-negative MSM evaluating the cost-effectiveness for inclusion of qHPV vaccine as adjuvant/secondary prevention strategy after treatment for initial HSIL. The vaccine efficacy was defined as the decrease in the hazards of developing recurrent HSIL. Using the outputs from the probabilistic sensitivity analysis, we estimated the population-level expected value of perfect information (pEVPI), and population-level expected value of partial perfect information (pEVPPI) for key model parameters including HSIL to anal cancer progression vaccine efficacy, probability of HSIL recurrences, HPV 16/18 incidence, and utilities. The population-level values were estimated for the number of MSM who would be potentially benefited from the vaccination over the next 20 years at an annual discount rate of 3%.

Result: The pEVPI in HIV-positive and HIV-negative MSM at willingness-to-pay threshold of $100,000/quality-adjusted life year (QALY) were $0 and $580,000, respectively. The two parameters with highest expected value of partial perfect information (pEVPPI) were vaccine efficacy (at $0/QALY ICER in HIV-positive and $200,000/QALY in HIV-negative MSM) and HSIL to anal cancer progression (at $0/QALY ICER in HIV-negative and $195,000/QALY in HIV-positive MSM). The EVPPI for other parameters—probability of HSIL recurrences, HPV 16/18 incidence, and utilities—were low.

Conclusion: In HIV-positive MSM, a future clinical trial may not be worthwhile, and implementation of the vaccination policy sooner rather than later should be a priority. In HIV-negative MSM, a future research could be potentially worthwhile if the fixed cost of research is less than $580,000. In both HIV-positive and HIV-negative MSM, further research regarding the estimation of HSIL to anal cancer progression may not be worthwhile. The lower EVPPI associated with the parameters like probability of HSIL does not mean that additional research about these inputs should take a lower priority, the low values indicate that precise estimates could be obtained from less expensive observational studies.