Cost-consequences evalutation between bivalent and quadrivalent HPV vaccines in Italy: the potential impact of different cross-protetion profiles

Objectives. Two human papillomavirus (HPV) vaccines are currently available: a bivalent HPV-16/18 and a quadrivalent HPV-6/11/16/18 vaccine. The vaccines may have different sustained- and cross-protection levels against non-vaccine oncogenic HPV-types. This study investigated the potential difference in clinical and economic impacts provided by two HPV vaccines in Italy. Methods. A prevalence-based model estimated the potential net difference in HPV-related lesions (abnormal pap smear, cervical intraepithelial neoplasia (CIN), cervical cancer (CC) and genital warts (GW)) and associated costs generated by the two vaccines. Incidence and treatment costs were obtained from Italian and European sources. Vaccine efficacy rates were based on published data for each vaccine. Lifetime vaccine efficacy was assumed. Results are reported over one year after reaching a steady state. Sensitivity analyses were performed on the lesion incidence, vaccine effectiveness, treatment costs and sustained protection. Results. The bivalent vaccine would prevent an additional reduction of 7976 abnormal pap smears; 601 CIN1; 1826 CIN2/3 and 295 CC cases compared to the quadrivalent vaccine while 25,848 genital wart cases would be prevented by the quadrivalent vaccine. The additional cost averted with the bivalent vaccine was estimated at 2,385,354 per year compared to the quadrivalent vaccine. The most influential parameters were CC- and GW-related costs and the difference in sustained protection. Conclusions. Our model suggests that, in the Italian setting, the bivalent vaccine would prevent more precancerous and CC lesions than the quadrivalent vaccine. This translates into a greater cost averted for the bivalent vaccine, which could completely offset savings in GW-related costs associated with the quadrivalent vaccine. (C) 2011 Elsevier Inc. All rights reserved.