Human Papillomavirus (HPV) Prevalence, Temporal Dynamics and Association with Abnormal Cervical Cytology Findings in Women from Croatia: Is there a Compounding Effect of Low-Risk/High-Risk HPV Co-Infection?

Background Human papillomavirus (HPV) is a major risk factor for cervical dysplasia and invasive cervical cancer; therefore, regular screening by cervical smear cytology or HPV testing is recommended. We aimed to determine the overall and risk group-specific HPV prevalence, age distribution, and temporal trends and to appraise the correlation of HPV positivity with abnormal cervical cytological findings. Methods This retrospective, single-center study involved a total of 751 women (aged 18 - 67) concurrently subjected to HPV DNA testing and cervical cytology evaluation over a 10-year period in Zagreb, Croatia. Digene HC2 HPV DNA test (Qiagen Corporation, USA) was employed in screening specimens for both low-risk and high-risk HPV risk groups. The cytology was reported using the Bethesda system and in accordance with uniform classification of uterine cervix cytological findings in Croatia Zagreb 2002. Statistical significance was set at p Results The overall HPV prevalence in our study population was 48.6%, and the 18 - 30 age group presented with the highest infection burden (p = 0.046). A decrease in low-risk and high-risk mono-positivity has been observed over the 10-year period; conversely, there was a significant increase in low-risk/high-risk co-positivity (p = 0.007). Low-risk/high-risk HPV co-infection resulted in a compounding effect which increased the occurrence of abnormal cells, HPV-associated changes and low grade squamous intraepithelial lesions (LSIL/cervical intraepithelial neoplasia grade I) in cervical cytology when compared to mono-infection with either low-risk or high-risk HPV. On the other hand, such effect has not been demonstrated for high grade squamous intraepithelial lesions (HSIL/ cervical intraepithelial neoplasia grades II and III). Conclusions The overall HPV prevalence in female outpatients was high, underscored with rising co-positivity rates. Such co-infection with both low-risk and high-risk HPV (predominantly seen in women younger than 30) can exhibit a compounding effect in the occurrence of cytological abnormalities and low grade squamous intra-epithelial lesions (LSIL), which has to be considered in future diagnostic and screening algorithms.