To examine the incremental effectiveness and cost-effectiveness of switching from cytology-based routine screening to primary HPV testing in Quebec (Canada), assuming 9-valent HPV vaccination.
We used HPV-ADVISE, an individual-based transmission-dynamic model of 18 HPV types and related diseases calibrated to Canadian-specific data. We compared cytology-based screening vs. switching to primary HPV-testing (Cobas 4800 test & triage of HPV-positive women by cytology) in 2018. For vaccination impact predictions, we modelled Quebec’s vaccination program: vaccination coverage=80%, start of vaccination=2008, gender-neutral 9-valent vaccination. For our base-case Cytology screening scenario, we used Quebec’s proportion of women who ever had a cytology test, and current age distribution of first screening and adherence to screening intervals. For HPV testing scenarios, we varied age at start of screening and screening intervals. We used a health care provider perspective, 3% discount rate, 2018-2050 time horizon, and $40,000/QALY-gained cost-effectiveness threshold. Predictions are annual averages for a population of 10 million.
In Quebec, switching to HPV screening was predicted to result in substantial cost savings vs. Cytology screening (savings of $27-38 million/year on average), under scenarios where age at start of screening was 25-35 years old, and intervals between tests were between 5-10 years. However, the only HPV screening strategy investigated with equal or lower rates of cervical cancer was when assuming age at start is 25 years and interval between tests is 5 years. Older age at start or wider intervals led to a predicted increase in cervical cancer cases. In terms of cost-effectiveness, HPV screening every 10 years initiated at age 30 years was predicted to be the optimal scenario. Although this scenario could lead to a small increase in cervical cancers, it would also result in a substantial decrease in false positives that are referred to colposcopy. Consequently, the model predicts that the gains in Quality-Adjusted Life-Years (QALY) related to screening outcomes outweigh the QALY loss related to the increase in cancer cases.
In Quebec, switching from Cytology to HPV screening is predicted to produce substantial cost savings and important reductions in false positive rates, if there is good adherence to the recommended screening intervals. However, the only scenario predicted to decrease cervical cancer rates is 5-yearly HPV screening initiated at age 25 years. Finally, HPV-screening every 10 years initiated at age 30 is likely the most cost-effective scenario, although it could lead to a slight increase in the number cervical cancers.