Health and economic impact of HPV 16 and 18 vaccination and cervical cancer screening in India

Abstract

Cervical cancer is a leading cause of cancer death among women in low-income countries, with approximately 25% of cases worldwide occurring in India. We estimated the potential health and economic impact of different cervical cancer prevention strategies. After empirically calibrating a cervical cancer model to country-specific epidemiologic data, we projected cancer incidence, life expectancy, and lifetime costs (I$2005), and calculated incremental cost-effectiveness ratios (I$/YLS) for the following strategies: pre-adolescent vaccination of girls before age 12, screening of women over age 30, and combined vaccination and screening. Screening differed by test (cytology, visual inspection, HPV DNA testing), number of clinical visits (1, 2 or 3), frequency (1 x , 2 x , 3 x per lifetime), and age range (35-45). Vaccine efficacy, coverage, and costs were varied in sensitivity analyses. Assuming 70% coverage, mean reduction in lifetime cancer risk was 44% (range, 28-57%) with HPV 16,18 vaccination alone, and 21-33% with screening three times per lifetime. Combining vaccination and screening three times per lifetime provided a mean reduction of 56% (vaccination plus 3-visit conventional cytology) to 63% (vaccination plus 2-visit HPV DNA testing). At a cost per vaccinated girl of I$10 (per dose cost of $2), pre-adolescent vaccination followed by screening three times per lifetime using either VIA or HPV DNA testing, would be considered cost-effective using the country's per capita gross domestic product (I$3452) as a threshold. In India, if high coverage of pre-adolescent girls with a low-cost HPV vaccine that provides long-term protection is achievable, vaccination followed by screening three times per lifetime is expected to reduce cancer deaths by half, and be cost-effective.

Figure 1

Model calibration. Selected model output from a random sample of good-fitting parameter sets are compared with the 95% confidence intervals of the empirical data (solid black lines) including HPV type distribution in cervical disease (upper panel) and age-specific cancer incidence rates (lower panel). Additional calibration results can be found in the Supplementary Appendix.

Figure 2

Reduction in lifetime risk of cervical cancer. The mean reduction in lifetime risk of cervical cancer is shown with strategies using either vaccination or screening (upper panel), and strategies combining both vaccination and screening (lower panel). The range represents the minimum and maximum reductions achieved for each strategy across the good-fitting parameter sets.

Figure 3

Impact of vaccination coverage, screening coverage, and vaccine efficacy on clinical benefits. This figure depicts how cancer reduction is influenced by different levels of vaccination and screening coverage with a combined strategy of vaccination plus screening three times per lifetime using two-visit HPV DNA testing. Cancer reduction is on the y axis, and vaccination coverage on the x axis. The coloured bars represent different coverage levels for screening (pale yellow, 20%; gold, 40%; green, 60%; orange, 80%; blue, 100%). The lines represent a strategy of vaccination alone at different levels of vaccine efficacy (white, 70%; light grey, 80%; dark grey, 90%; black, 100%). The dashed red line represents a threshold of 50% cancer reduction.