Effect of type-specific human papillomavirus incidence on screening performance and cost.

BACKGROUND: Implementation of human papillomavirus (HPV) vaccination is expected to change the epidemiology of HPV infection. METHODS: Using age-dependent (inhomogeneous) Markov chains, we tested the effect of type-specific (ie, HPV-16/HPV-18 and other high-risk HPV types) HPV incidence on 3 screening strategies in a cohort of 100,000 women, starting screening at the age of 25 years and continuing until the age of 34 years. All the strategies started with an HPV test; if the result was positive, the next step was triage with cytology (strategy 1), cytology and colposcopy together (strategy 2), or colposcopy only (strategy 3). Published background data were used for the models. RESULTS: Strategy 2 had the highest sensitivity; the absolute number of missed cervical intraepithelial neoplasia (CIN)3+ cases was associated with HPV incidence in all the strategies, but their relative sensitivity remained unaffected. Strategy 2 was cheaper per diagnosed CIN3+ for very low HPV incidence rates, but this changed for higher incidence rates. For any given pair of HPV-16/HPV-18 and other high-risk-type incidence, the cost of the triage and the total cost of screening was highest in screening 2 and lowest in screening 1. For each screening strategy, the cost per diagnosed CIN3+ was mainly determined by the incidence of HPV-16/HPV-18, and the cost of the triage and the total screening cost by the incidence of other high-risk types. CONCLUSIONS: Type-specific HPV incidence affects the absolute number of missed CIN3+ cases and the cost of screening in a mathematically describable way and can be used for prediction of changes in these outcomes with changing HPV epidemiology.

Prevalence and distribution of high-risk human papillomavirus in Greece.

As knowledge of regional human papillomavirus (HPV) type distribution is essential for the optimization of prevention strategies, this study was carried out to explore the prevalence and type distribution of high-risk HPV in a screening population across Greece. Cervical samples were collected by local physicians and nurses in hospitals and health centers across the country from 4139 women attending for cervical cancer screening. High-risk HPV-DNA was detected by using Hybrid Capture-2 (HC2) and positive samples with adequate cellular content were further typed by restriction fragment length polymorphism-polymerase chain reaction. Almost six percent (5.9%) of women tested positive in HC2. The most common type was HPV16 (1.4% in the whole sample and 32.4% of the typed samples), followed by HPV53 (0.6 and 14.0%, respectively), HPV31 (0.6 and 12.9%, respectively), HPV35 (0.5 and 12.3%, respectively), HPV51 (0.4 and 7.8%, respectively), HPV18 (0.3 and 7.3%, respectively) and 22 more types. Almost 15% of the typed samples showed a coinfection with two HPV types and 2.1% with three types. There was a bimodal distribution by age, with the highest peak in women 20-29 years old and a lower peak in women 50-59 years old. Apart from the types originally included in HC2 cocktail, PCR analysis identified 15 more types (HPV6, HPV11, HPV34, HPV37, HPV38, HPV42, HPV53, HPV54, HPV55, HPV61, HPV62, HPV66, HPV73, HPV82, HPV83). Eleven percent of HC2-positive results arose from single-type infections with HPV53 (10%) and HPV66 (1%), which are potentially high-risk types. In conclusion, HPV16 is the most common type in the largest Greek screening sample used to date and, together with its related types, accounts for more than half of high-risk HPV infections. Approximately 10% of positive HC2 results arise from HPV53, which is not normally detected by the test, but may be clinically significant.