In Thailand, cervical cancer is a leading cause of death among women. The Ministry of Public Health is focused on reducing cervical cancer with national screening efforts, one of which has increased access to pap tests. The burden of cervical cancer remains high, however. This study seeks to evaluate the clinical and cost-effectiveness of HPV DNA primary screening as compared to pap primary algorithms, from a payor perspective, with several triage strategies, including p16/Ki-67 dual-stain cytology and colposcopy.
A Markov model was used to compare 4 strategies for women ages 30-65 (per country recommendations), across a 100-yr horizon, assuming a 5-yr primary screening interval for the strategies evaluated: 1) HPV DNA primary testing every 5 yrs with pooled high-risk positive results sent to colposcopy;2) HPV primary testing with pooled high-risk positive results triaged with p16/Ki-67 dual-stain cytology;3) pap primary with ≥ASCUS results to colposcopy;4) pap primary with ≥ASCUS results triaged with p16/Ki-67 dual-stain cytology. Values for HPV DNA testing and pap screening sensitivity and specificity were obtained from the Addressing THE Need for Advanced HPV Diagnostics (ATHENA) trial. Dual-stain cytology data are from the Primary ASCUS LSIL Marker Study (PALMS) and ATHENA trials. Costs were derived from a national tertiary care hospital in Bangkok. Costs and quality adjusted life-years (QALYs) were discounted at 3.5% annually. Sensitivity analyses were conducted to assess impact of cost and clinical inputs on incremental cost-effectiveness ratios and outcomes.
HPV DNA primary screening with colposcopy triage offers comparable cost-effectiveness to HPV DNA primary screening with dual-stain cytology triage. For pap primary testing, colposcopy triage was dominant to dual-stain triage due to the low cost of colposcopy and pap in Thailand. All HPV strategies were cost-effective ($20,000 US threshold), but in Thailand, the convention is to use a GDP threshold closer to $6000, thus testing more than every 5 yrs, though cost-effective, may not be acceptable. Because HPV primary testing offers greater sensitivity than pap, such strategies may provide greater value when longer screening intervals cannot be avoided. Notably, HPV DNA primary testing with dual-stain cytology triage represents the optimal strategy to reduce cervical cancer, though this would require investment in tests and triage. All HPV primary strategies modeled allow for early detection of cervical precancer and cancer, reduction in mortality, and lower treatment costs. These factors will grow even more important as Thailand works to implement a sustainable national screening program.