Tuesday, March 18, 2008

A Natural History Model to Estimate the Clinical Impact of a Cervical Cancer Vaccine Candidate among Racial and Ethnic Populations in the United States

Vivek Pawar1, Douglas CA Taylor1, Denise Kruzikas2, Ankur Pandya1, Shalini Naik1, Kristen Gilmore1, David Thompson3, and Milton Weinstein4. (1) Health Economics and Outcomes Research, i3 Innovus, 10 Cabot Rd, Suite 304, Medford, MA, USA, (2) US Health Outcomes, GlaxoSmithKline, One Franklin Plaza, Philadelphia, PA, USA, (3) Global Health Economics, i3 Innovus, 10 Cabot Rd, Suite 304, Medford, MA, USA, (4) Harvard School of Public Health, Boston, MA, USA

Learning Objectives for this Presentation:
By the end of the presentation, participants will be able to understand how cervical cancer (CC) vaccination has the potential to reduce disparities between ethnic groups in the United States (US).

Despite widespread CC screening, variations in CC incidence across racial/ethnic populations persist.

To estimate the long-term clinical impact of a CC vaccine candidate and its potential to address these disparities.

A mathematical model simulated the lifetime natural history of human papillomavirus (HPV) infection in all 12-year-old White, Black, Asian, Native-American, and Hispanic (White and non-White), females. The model was calibrated using cohort-specific cervical screening patterns, and CC incidence and mortality. Assuming constant screening practices over time, the impact of the vaccine candidate, with efficacy against HPV 16/18 infection and preliminary evidence of cross-protection against other oncogenic types, was compared with no vaccination. Vaccination coverage ranged from 70 to 100%.

Without vaccination, the model predicted CC incidence rates of 8.4, 9.2, 5.9, 7.0, and 9.3 per 100,000 females in White, Black, Asian, Native-American, and Hispanic cohorts, respectively. Corresponding rates of CC mortality were 2.0, 2.3, 2.0, 2.0, and 2.4 per 100,000 females. With 100% coverage, 78-82% reduction in CC incidence and mortality was observed for each cohort compared to no vaccination. At 70% coverage, CC incidence and mortality rates were estimated to decrease across all racial/ethnic cohorts by 55-58%. Furthermore, with vaccination, the degree of disparity between the racial/ethnic groups was reduced by 57-100%.

The model estimated that vaccination may potentially reduce cervical cancer incidence and mortality for all females, and as a result, may also address disparities between racial/ethnic populations. Effective educational and outreach programs to ensure access to primary and secondary cervical cancer prevention methods may help improve cervical cancer outcomes for all women.