BACKGROUND: The development of human papillomavirus (HPV)-relateddiseases is not understood perfectly and uncertainties associatedwith commonly utilized probabilistic models must be considered. Thestudy assessed the cost-effectiveness of a quadrivalent-based multicohortHPV vaccination strategy within a Bayesian framework. METHODS: Afull Bayesian multicohort Markov model was used, in which all unknownquantities were associated with suitable probability distributionsreflecting the state of currently available knowledge. These distributionswere informed by observed data or expert opinion. The model cyclelasted 1 year, whereas the follow-up time horizon was 90 years. Precancerouscervical lesions, cervical cancers, and anogenital warts were consideredas outcomes. RESULTS: The base case scenario (2 cohorts of girlsaged 12 and 15 y) and other multicohort vaccination strategies (additionalcohorts aged 18 and 25 y) were cost-effective, with a discountedcost per quality-adjusted life-year gained that corresponded to &OV0556;12,013,&OV0556;13,232, and &OV0556;15,890 for vaccination programs basedon 2, 3, and 4 cohorts, respectively. With multicohort vaccinationstrategies, the reduction in the number of HPV-related events occurredearlier (range, 3.8-6.4 y) when compared with a single cohort. Theanalysis of the expected value of information showed that the resultsof the model were subject to limited uncertainty (cost per patient=&OV0556;12.6).CONCLUSIONS: This methodological approach is designed to incorporatethe uncertainty associated with HPV vaccination. Modeling the cost-effectivenessof a multicohort vaccination program with Bayesian statistics confirmedthe value for money of quadrivalent-based HPV vaccination. The expectedvalue of information gave the most appropriate and feasible representationof the true value of this program. Copyright © 2012 by LippincottWilliams & Wilkins.