Candidate for the Lee B. Lusted Student Prize Competition
Purpose: Since 1991, the Norwegian Coordinated Cervical Cancer Screening Program has invited women to cytology-based screening every three years. Although a reduction in cervical cancer has been observed, it remains among the top three most frequent cancers for women aged 25-49 and may be further reduced by new screening technologies. In addition, vaccination against human papillomavirus, the necessary cause of cervical cancer, may impact optimal screening strategies. We evaluated the cost-effectiveness of alternative primary screening strategies for vaccinated and unvaccinated women to inform policy recommendations in Norway.
Method: We used likelihood-based methods to calibrate a first-order Monte Carlo simulation model to reflect the natural history of HPV-induced cervical cancer in Norway. The current screening strategy involving cytology only was compared to a strategy involving cytology at younger ages, followed by a switch to primary HPV-based screening, an option being actively considered by the Norwegian government. Pre-switch screening strategies included varying the management protocols for mildly abnormal results. Post-switch screening strategies included varying the age at which women switch to primary HPV testing (31 or 34 years), screening interval (3-6 years), and triage strategies for women with HPV-positive results. All costs were considered from the societal perspective. Additional sensitivity analysis included varying screening laboratory costs to reflect potential discrepancies between published reimbursement rates and true economic costs.
Result: Current cytology-only screening was less effective and more costly than proposed strategies that involve switching to primary HPV testing in older ages. For unvaccinated women, switching at age 31 to primary HPV testing every 4 years with cytology as a triage for HPV-positive results was most cost effective at 460,000NOK/YLS (≈$72,000/YLS) given a Norwegian cost-effectiveness threshold of approximately 500,000NOK/YLS (≈$78,000/YLS). For vaccinated women, the preferred screening strategy was the same, but with intervals widened to every 6-years after the switch age of 31. Strategies involving immediate diagnostic referral of young women with mildly abnormal cytology results were not cost-effective. By using published reimbursement rates for laboratory costs that were lower than our base-case estimates, we found that the optimal strategy for vaccinated women allowed for more intensive follow-up of HPV-positive women.
Conclusion: Strategies involving a switch to HPV testing for primary screening in older women is expected to be cost-effective, compared with current screening recommendations in Norway.