Prevalence, Incidence and Predictors of Anal HPV Infection and HPV-Related Squamous Intraepithelial Lesions in a Cohort of People Living with HIV

<b>Background:</b> Anal HPV infection can cause squamous intraepithelial lesions (SILs), which are precursors of anal squamous cell carcinoma (SCC). The early detection of HPV infections and improvement of effective screening programmes are, therefore, essential to prevent progression from pre-cancerous lesions to SCC, especially in people living with HIV (PLWH), who represent a population at higher risk of HPV infection and associated lesions. Among prevention strategies, HPV vaccination is relevant too, but its efficacy in persons already infected by HPV is still debated. <b>Methods</b>: This is a retrospective single-center study on a cohort of PLWH who performed longitudinal screening for anal dysplasia and HPV infection. The screening included cytological and molecular analyses. <b>Results</b>: A total of 110 PLWH performed at least one anal HPV screening, with an overall prevalence of HPV infection of 86.4% [23.6% low risk (LR)-HPV and 62.7% high risk (HR)-HPV genotypes]. Abnormal cytology was demonstrated in 39.1% of subjects, of whom ASCUS 6.4%, LSIL 30.9% and HSIL 1.8%. In total, 80 patients (72.7%) had an available longitudinal screening. No patient developed SCC during follow-up. However, a high incidence of new cytological abnormalities and new HPV infections was observed. On the other side, clearance of some HPV genotypes was also frequent, confirming that HPV infection is a dynamic process. A CD4 cell count > 500/mmc was an independent predictor of HPV clearance. HPV vaccination was performed on 30.9% of patients. A trend toward an increased clearance of HPV genotypes included in 9-valent vaccine was observed in vaccinated patients (40.6% versus 30.8% in unvaccinated, <i>p</i> = 0.079). <b>Conclusions</b>: A high prevalence of HPV infection and SILs was observed in our cohort of PLWH. A high incidence of new HPV infections and HPV-associated lesions was also observed in the longitudinal cohort, highlighting the need of strengthening immunization programs and continuous screening for anal HPV infection. Whether HPV vaccination may be efficacious in patients already infected by HPV remains to be determined.