IDENTIFYING RESOURCE USE AND CAPACITY CONSTRAINT TRADEOFFS ASSOCIATED WITH IMPLEMENTING NEW SCREENING GUIDELINES IN NORWAY

Purpose: New screening strategies that involve primary human papillomavirus (HPV) DNA testing are actively being considered by the Norwegian government, but capacity constraints (e.g., number of gynecologists to perform colposcopies), and uncertainty around resource tradeoffs, remains a challenge for implementation. We aimed to assess the tradeoffs of health benefits and resource use associated with alternative ages to switch to primary HPV testing, routine screening frequency (i.e., interval) and the follow-up intensity of HPV-positive women with no cytologic abnormalities (HPV+/Cyt-). 

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 alternative strategies that switch women to primary HPV-based screening at age 25, 28, 31 or 34 for alternative routine screening frequencies (every 3-10 years). For HPV+/Cyt- women, we varied the follow-up interval (6, 12 or 18 months), and the number of persistent HPV+/Cyt- results (1, 2 or 3) required before prompting referral to diagnostic colposcopy. Model outcomes included the number of colposcopy referrals and the reduction in lifetime cancer risk compared to the current cytology-only screening strategy. 

Result: Changing the frequency of the routine screening interval or the age to initiate primary HPV-based screening resulted in the largest variations in cancer risk reduction compared to changing the follow-up management of HPV+/Cyt- women. Conversely, colposcopy referral rates can more than triple when strategies involving screening every 3-5 years are paired with more intensive follow-up management strategies for HPV+/Cyt- women, particularly for younger switch ages. Strategies that simultaneously improve health benefits and control colposcopy referral rates (i.e., <15% increase compared to current levels) involve screening every 5 years with less intensive follow-up management of HPV+/Cyt- women (i.e., 2 persistent results 12 months apart), while strategies that involve screening every 4 years or more frequently require the health system to accept increases in colposcopy referral rates. 

Conclusion: Strategies involving primary HPV-based screening may improve health benefits with respect to cancer reduction, but may also increase colposcopy utilization. When faced with capacity constraints, more frequent routine screening intervals at younger primary initiation ages should be paired with the least intensive follow-up strategies in order to control colposcopy referral rates.