Human papillomavirus (HPV) infection doubles the risk of HIV acquisition for women, results of a systematic review and meta-analysis published in the online edition of AIDS suggest.
The infection also increased the risk of HIV acquisition for heterosexual and gay men, but only two studies examining the association in these populations could be identified.
Between a fifth and a third of all HIV transmissions were attributed to prevalent HPV infection. A number of descriptive studies have pointed to an association between prevalent HPV infection and an increased risk of acquisition of HIV. An international team of investigators therefore conducted a systematic literature review and meta-analysis to determine the association between this common infection and HIV acquisition in three populations: heterosexual women; gay and other men who have sex with men; and heterosexual men. They also wished to see how many HIV transmissions could be attributed to the presence of HPV infection.
Nested case-controlled and cohort studies published in a peer-reviewed journal or presented to a major conference before July 2011 were eligible for inclusion in the analysis.
Only eight studies met the investigators’ criteria: six in women and one each in gay and heterosexual men. A total of 12,750 patients were included in these studies. None of the studies had as its primary aim assessment of the association between the presence of HPV and infection with HIV.
The investigators combined the results of the six studies conducted with women. They did not consider it appropriate to add the two studies conducted with men to this analysis.
The presence of HPV infection doubled the risk of HIV acquisition for women (aHR = 2.06; 95% CI, 1.44-2.94). The risk was similar for HPV genotypes associated with a high risk of cervical cell changes and cancer (aHR = 1.99; 95% CI, 1.54-2.46) and low-risk strains of the virus (aHR = 2.01; 95% CI, 1.27-3.20).
Vaccines that provide a high level of protection against incident infection with the HPV strains most associated with cervical cancer have recently been approved for use in the UK. The meta-analysis showed that infection with the genotypes covered by the quadrivalent vaccine (Gardasil) doubled the risk of acquisition of HIV (aHR = 2.00; 95% CI, 1.00-3.99).
“Clarification of the findings presented in this study through well-conducted research is needed in high HPV/HIV settings, in order to assess whether HPV vaccination might have an effect on HIV incidence,” comment the researchers.
For gay men, infection with two or more HPV genotypes more than tripled the risk of HIV acquisition (aHR = 3.5; 95% CI, 1.2-10.6). For heterosexual men, the presence of any HPV in the glans/coronal sulcus of the penis was associated with an increased risk (aHR = 1.8; 95% CI, 1.1-2.9).
“Combining the studies in women revealed a near doubling of risks when an HPV genotype was identified prior to HIV acquisition, with similar associations seen in the two studies in men,” comment the authors.
Neither the cervical nor the anal cell abnormalities that can be caused by HPV increased the risk of infection with HIV.
They calculated that between 21 and 37% of all HIV infections could be attributed to the presence of HPV.
However, the authors had concerns about the quality of all the studies included in their analysis. Two of the studies involving women did not adjust for sexual behaviour, whereas others did not record data on transactional sex. “It is particularly difficult to collect sufficiently detailed, rigorous, sexual behaviour data and for this reason, residual confounding may affect all studies,” emphasise the researchers.
Houlihan CF et al. HPV infection and increased risk of HIV acquisition. A systematic review and meta-analysis. AIDS 26: online edition. DOI: 10.1097/QAD.0b013e328358d908, 2012.