Abstracts Health Sciences

Identifying risk factors for anal human papillomavirus type 16 infection and assessing the acceptability of screening for anal cancer and its precursors in women living with HIV

by Elaina Kaufman

Background: Anal infection with oncogenic human papillomavirus (HPV) can lead to anal cancer. HPV type 16 is both highly oncogenic and highly prevalent. Given the high rate of anal cancer in women living with HIV (WLHIV), routine screening is being considered. Decisions regarding screening and prevention require knowledge of the risk factors at each step in the development of anal cancer, and confirmation of the acceptability of screening tests. Objectives: The first manuscript aims to elucidate the risk factors for prevalent anal HPV 16 infection in WLHIV. The second manuscript aims to assess the acceptability of 3 anal cancer screening procedures (anal swabs for cytology or HPV testing, high-resolution anoscopy with biopsies, and digital anorectal examination) in WLHIV. Methods: This manuscript-based thesis is based in the EVVA study ('Evaluation of HIV, HPV, and Anal Intraepithelial Neoplasia in women'), an epidemiological cohort study in 151 WLHIV. Risk factors for anal HPV 16 were identified using logistic regression. Acceptability questionnaires were analyzed using descriptive and inferential statistics. Results: In age-adjusted multivariable analyses, factors associated with prevalent anal HPV 16 infection were past anogenital herpes (Odds Ratio[OR]=6.6; 95% Confidence Interval [CI]: 1.8-23.9; p=0.004), nadir CD4 count ≤200 cells/μL (OR=5.9; 95% CI: 1.6-21.2; p=0.007), current smoking (OR=5.1; 95% CI: 1.4-18.9; p=0.014), and concurrent cervical HPV 16 infection (OR=27.7; 95% CI: 2.3-326.7; p=0.008). Effect modification was observed between past anogenital herpes and lifetime number of anal sex partners (OR for interaction = 0.045; 95% CI: 0.003-0.773 p=0.003). All 3 screening procedures were considered necessary and very acceptable by the majority of women. Screening intervals of 2 years for digital anorectal examinations and anal swabs, and 5 years for high-resolution anoscopy, were considered acceptable by over 90% of women. Pain accounted for most low acceptability responses. Conclusions: Our results can help identify women at greatest risk of anal HPV 16 infection. These women are more likely to benefit from screening, through either anal HPV testing or cytology. If screening programs were to be considered, currently available anal cancer screening procedures would be acceptable for most WLHIV, particularly with improvements to pain management. Contexte: Une infection anale par un virus du papillome humain (VPH) de type oncogène peut mener au cancer anal. Le VPH 16 est hautement oncogène et très prévalent. Compte tenu du taux élevé de cancer anal chez les femmes vivant avec le VIH (FVVIH), le dépistage systématique est envisagé. Les décisions concernant le dépistage et la prévention exigent la connaissance des facteurs de risque pour chaque étape du développement du cancer anal et la confirmation de l'acceptabilité des procédures de dépistage. Objectifs: Le premier manuscrit vise à identifier les facteurs de risque pour l'infection prévalente anale du VPH 16 chez les FVVIH. Le deuxième… Advisors/Committee Members: Alexandra De Pokomandy (Internal/Supervisor), Tyler Williamson (Internal/Cosupervisor2).