Purpose:
To investigate the health effects of primary screening for human papillomavirus (HPV) as compared to primary cytology screening in uncontrolled screening situations.
Method:
The microsimulation screening analysis (MISCAN) model was used to determine the health effects of using the HPV test instead of cytology as the primary screening method, for a cohort of 10 million women. By varying both the age at which women are invited for the first time (20 to 30 years) and the interval length between two consecutive invitations (1 to 5 years), eight screening situations that are realistic for current practice in various regions in the world were constructed. The model was based on the Dutch situation, but important variables such as background risk, HPV prevalence and test characteristics of both cytology and the HPV test were varied to represent international ranges. Furthermore, threshold analyses were performed on the amount of utility lost due to a false positive result and due to both a screen test and a false positive result.
Result:
When women aged 30 to 60 years were invited every 5 years (i.e. the Dutch screening program), 24 deaths per 100,000 simulated women were prevented with primary HPV screening compared to primary cytology (Figure 1). Only 7 deaths were prevented when women aged 20 to 65 years were invited annually. Moreover, in the latter case the number of additional referrals for colposcopy was expected to be 3,5 times higher than in the former case (5,033 versus 1,404 per 100,000 simulated women). For the intensive screening schedule, quality adjusted life years (QALYs) were lost by switching from primary cytology to primary HPV screening. Primary HPV screening would in this case only incur health benefits if the utility loss resulting from a false positive result decreased from 22 hours (i.e. equivalent to the amount of utility loss per false positive result in the base case scenario) to at most 7 hours.
Conclusion:
Primary HPV screening should only be considered in situations where screening is well controlled. If primary HPV screening is used in settings with frequent screening at young age, it will most likely lead to a loss in QALYs.
