Estimating the age distribution of disease-causal HPV infection in women with high-grade cervical intraepithelial neoplasia in Denmark, Estonia, Norway, Slovenia, and Sweden: A modeling study.

The age distribution of disease-causal human papillomavirus (HPV) infections that lead to high-grade cervical intraepithelial neoplasia (CIN2+) is not well understood in Europe. The objective of this study was to estimate the age at acquisition of disease-causal HPV infection in women diagnosed with CIN2+ in Denmark, Estonia, Norway, Slovenia, and Sweden. A previously published discrete event simulation model was modified to estimate the age of disease-causal HPV infection for females diagnosed with CIN2+ by comparing predicted and observed age distributions of CIN2+ diagnoses using a chi-square goodness-of-fit test. Scenario and sensitivity analyses were also performed. The predicted median age (years) of disease-causal HPV infection was 23.69 in Denmark, 26.73 (narrow case definition for CIN2+ diagnosis) and 28.34 (broad definition) in Estonia, 29.32 in Norway, 32.03 in Slovenia, and 26.33 in Sweden. The percentage of women aged over 26 and 45 years with a predicted causal HPV infection was 42.7%/8.1% (26/45 years) in Denmark, 52.8%/9.0% (narrow definition) and 57.9%/12.7% (broad definition) in Estonia, 64.7%/11.9% in Norway, 72.3%/21.4% in Slovenia, and 51.2%/9.4% in Sweden. Model results were robust to variations in inputs and parametrization tested in scenario and sensitivity analyses. A considerable proportion (42.7-72.3%) of causal HPV infections are projected to occur in women over age 26, while 8.1%-21.4% are projected to occur in women over the age of 45. These findings highlight a need to consider HPV vaccination for previously unvaccinated women to reduce the burden of CIN2+ and cervical cancer.