The Impact of HPV Vaccination: Insights from an Italian Study

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HPV Vaccination

A new study evaluating HPV vaccination impact on morbidity and mortality in Italian women published its findings recently in the journal of Population Health Metrics.

Human papilloma virus or HPV causes cervical cancer. HPV is also involved in the development of cancers of the vagina, vulva, penis, anus, head, and neck, as well as nonmalignant anogenital warts and recurrent respiratory papillomatosis. Cervical cancer is the fourth most common cancer in women, with 528,000 new cases and 266,000 deaths in 2012.1

Gardasil manufactured by Merck and Cervarix manufactured by Glaxo are the two vaccines currently available for preventing the transmission and infection of specific strains of HPV. While data on the efficacy of these vaccines in preventing HPV infection are available, data on HPV-associated disease impact and HPV vaccination impact on morbidity and mortality in Italian women was lacking.

A new study evaluated the effects of HPV vaccination on women’s health in Italy. The results of the study were published recently in Population Health Metrics.2 The study developed a model comprised of multiple disease states and transitions between these states, which included a healthy state, the presence of genital warts, grade 1 and grade 2/3 cervical intraepithelial neoplasia, cervical cancer, anal cancer, and death. The model was adapted based on data available in the scientific literature about HPV and associated diseases and Italian life tables. A number of indicators were estimated to assess the impact of disease and vaccination on health, which included life expectancy, quality-adjusted life years (QALY), Disability-Adjusted Life Years (DALY), and attributable risk (AR).

The model showed that life expectancy in a theoretical cohort of 100,000 Italian women was 83.1 years, which increased to 83.2 years with HPV vaccination. QALYs, which scales life expectancy by the quality of life among the survivors, was 82.7 years in the non-intervention group and 82.9 years in the HPV vaccination group.  This means that HPV related diseases rob women of 0.35 years of perfect health over their lifetime.

DALYs, which takes into account the impact of disease on the quality and quantity of life and is the sum total of years lost due to mortality and disability, was reduced by 0.6 years with HPV vaccination. AR, which is indicative of the incidence of HPV-related disease in the vaccinated and non-vaccinated groups, was 145 per 100,000 in the former and 265 per 100,000 in the latter group.

This is the first model to attempt to evaluate the long-term effects of the HPV vaccine on women’s health in Italy. These results indicate that the impact of HPV vaccination on overall mortality in Italian women was low. However, the vaccine had a significant impact on reducing the incidence of HPV-related disease, which may significantly cut healthcare costs and reduce the cost burden associated with lost productivity. When all of the factors were included the impact of the vaccination was remarkable.

Despite the simplifications inherent in the model, which include having a limited number of diseased states and making simplifying assumptions about transitions between these states, the model holds value in being able to estimate the HPV vaccination impact in a population over the long-term.

Written by Usha B. Nair, Ph.D.

References:

1) World Health Organization. Human Papillomavirus. http://www.who.int/immunization/diseases/hpv/en/. Updated: February 7, 2017. Accessed: October 08, 2017.

2) Marcellusi A. Impact of HPV vaccination: health gains in the Italian female population. Popul Health Metr. 2017 Sep 29;15(1):36. doi: 10.1186/s12963-017-0154-0. PubMed PMID: 28962572.