Oral HPV Infection among Indigenous Australians; Incidence, Persistence, and Clearance at 12-Month Follow-up.

BACKGROUND: Persistent oral human papillomavirus (HPV) infection is a risk factor for oropharyngeal squamous cell carcinoma (OPSCC). Indigenous Australians have a higher rate of OPSCC than non-Indigenous Australians. Risk factors for oral HPV persistence among Indigenous Australians are poorly understood. METHODS: Participants provided information on sociodemographic characteristics, health-related behaviors including tobacco and alcohol use, and sexual history. Participants additionally provided saliva samples for microbial genotyping. Negative log binomial regression models were used to evaluate associations of sociodemographic, health behavior, and sexual behavior indicators on incident, persistent, and cleared oral HPV infection at 12-month follow-up. Estimates were quantified as rate ratios (RR). RESULTS: Of the 1,011 participants recruited at baseline, 911 provided saliva samples that were beta-globin positive (a DNA integrity check), with 321 (35.3%) testing positive for any oral HPV infection. At 12-month follow up, saliva samples were obtained from 743 of the original 1,011 participants (73.5%). Among the 584 participants who provided beta-globin-positive saliva samples at baseline and 12-month follow-up, 24 (42.6%) had no oral HPV infection at both time points, 130 (22.2%) had new (incident) oral HPV infection at 12 months, 130 (22.2%) had persistent oral HPV infection (i.e., present at both baseline and 12 months), and 75 (12.8%) had oral HPV infection clearance from baseline to 12 months. Age of first giving oral sex and unsafe (unprotected) oral sexual behaviors were significantly associated with incidence; rural location of residence and ever received oral sex were significantly associated with persistence; and, rural location of residence and ever received oral sex were significantly associated with clearance of oral HPV infection. CONCLUSIONS: The incidence of oral HPV infection at both baseline and 12-month follow-up was high. Factors associated with persistence and clearance of oral HPV infections included location of residence and unsafe oral sexual behaviors. IMPACT: There are currently no studies available which have assessed oral HPV infection incidence, persistence, and clearance amongst Indigenous populations in Australia or even at a global level. The study has been able to identify risk factors associated with potential malignant changes in the oropharynx among Indigenous Australians.