Longer Use of Combination Antiretroviral Therapy Associated with Reduced Risk Of Cervical HPV

Abstract

Women infected with HIV may have a lower risk of testing positive for cervical human papillomavirus (HPV) if they have been taking combination antiretroviral therapy (cART) for a longer period of time, according to a prospective cohort study conducted in South Africa. (1) Relative to peers who were not receiving this therapy, study participants who were receiving cART had a reduction of two-thirds in the unadjusted odds of HPV types associated with a high risk of cervical cancer and a reduction of one-half in the unadjusted odds of HPV 16, one of the main cancer-causing types. Although these associations were no longer statistically significant after adjustment for covariates, duration of therapy remained an important indicator of risk: With each additional month that a woman used cART, the adjusted likelihood of testing positive fell by 5% and 6%, respectively, for high-risk types and for HPV 16. Between November 2009 and October 2011, investigators enrolled in the study non-pregnant, cancer-free South African women who were infected with HIV and had never taken cART. During twice-yearly follow-up visits, the women provided clinical, obstetric and sexual behavior data; underwent a Pap test; and gave blood samples for assessment of CD4 cell count and HIV viral load, and cervical samples for HIV and HPV DNA testing. The investigators used bivariate analyses to compare baseline characteristics between women who did and did not initiate cART, and modeled the probability of detection of HPV using multivariate logistic regression analysis as a function of whether women were on cART at a given visit and of the length of time they had been on this therapy. The 300 women studied were 35 years old, on average. Overall, 68% initiated cART after meeting the criteria in government guidelines; all were started on a regimen containing a non-nucleoside analogue reverse transcriptase inhibitor, standard practice at the time. About 46% of women who initiated cART and 65% of those who did not were black, and the majority (69% and 80%, respectively) had a partner. Mean duration of follow-up was 19 months among those who initiated cART and 12 months among those who did not. On average, the women who started cART stayed on this therapy for 16 months. Results showed that 94% of women tested positive for at least one high-risk type of HPV (type 16, 18, 31, 33, 35, 39, 45, 52 or 58) at some time during follow-up, and 42% specifically tested positive for HPV 16. In unadjusted analyses, relative to peers who were not using cART, women who were had a roughly 80% reduction in the odds of testing positive for any type of HPV (odds ratio, 0. …