Abstract
BACKGROUND.
Studies in women have shown an increased risk of HIV acquisition with prior HPV infection; however, few studies have been conducted among men. Our objective was to assess whether HPV-related external genital lesions (EGLs) increase risk of HIV seroconversion among men.
METHODS.
A total of 1379 HIV-negative men aged 18-70 years from the US, Mexico, and Brazil were followed for up to seven years and underwent clinical examination for EGLs and blood draws every six-months. HIV seroconversion was assessed in archived serum. Cox proportional hazards and marginal structural models assessed the association between EGL status and time to HIV seroconversion.
RESULTS.
29 participants HIV seroconverted during follow-up. Older age was associated with a lower hazard of HIV seroconversion. We found no significant difference in the risk of HIV seroconversion between men with and without EGLs (adjusted hazard ratio [HR]=0.94, 95%CI 0.32-2.74). Stratified analyses focusing on men that have sex with men found no association between EGLs and HIV seroconversion risk (HR=0.63, 95%CI 0.00-1.86).
CONCLUSION.
EGLs were not associated with higher risk for HIV seroconversion in this multinational population, although statistical power was limited as there were few HIV seroconversions. Results may differ in populations at higher risk for HIV.
Keywords: Genital Warts, HIM Study, HIV, EGL, HPV
Short Summary:
Studies have shown an increased risk of HIV acquisition with prior HPV infection HPV-related external genital lesions were not associated with higher risk for HIV seroconversion in this multinational population
Introduction
HIV and human papillomavirus (HPV) share acquisition risk factors. It is well known that HIV causes immune suppression, which increases the risk of HPV infection and progression to HPV-related disease, such as cervical cancers. A growing literature suggests that HPV infection may increase the risk for HIV acquisition.(1–5) Studies conducted among women (6–9) and men (10–12) consistently demonstrate an increased risk of HIV seroconversion with prior HPV infection. Understanding the role of other infectious diseases in the natural history of HIV infection can help improve HIV prevention efforts through a multifactorial approach.
HPV causes external genital lesions (EGLs) in men, most commonly genital warts. These lesions are associated with increases in CD4+ and CD8+ T-cells at the lesion. This increased number of HIV CD4+/CD8+ target T-cells is the presumed mechanism of elevated HIV susceptibility among those with HPV infection.(12–16) Immune cells are recruited to remove the lesion; if an individual is exposed to HIV at this same time, it may provide HIV more target cells to infect in the epidermis that may otherwise not reside there. Our objective was to assess whether HPV-related EGLs increase risk of HIV seroconversion among men.
Material and Methods
Study Population
The HPV infection in men (HIM) Study enrolled 4123 men aged 18-70 years living in Tampa, Florida, US; Cuernavaca, Mexico; and São Paulo, Brazil between July 2005 and June 2009. A full description of the study procedures has been published.(17, 18) Participants returned for study visits every six months for a physical exam and biospecimens were obtained.
All participants provided written informed consent. Study protocols were approved by the Institutional Review Boards at the University of South Florida (Tampa, FL, US), the Ludwig Institute for Cancer Research, the Centro de Referencia e Treinamento em Doencas Sexualmente Transmissiveis e AIDS (São Paulo, Brazil), and the Instituto Nacional de Salud Pública (Cuernavaca, Mexico).
HIV Sub-cohort
The HIM Study did not include HIV testing at enrollment or during follow-up. All HIM Study participants self-disclosed as HIV-negative at baseline. HIM Study participants had a serum sample collected at each study visit. At their follow-up visits in 2015, HIM Study participants were approached and asked for consent to test their stored serum for HIV; only men with at least three completed HIM Study visits were approached. HIV test results were disclosed to participants and to their respective health department. Those who tested HIV-positive were referred for care following local standard of care protocols.
Specimen Collection and laboratory testing
Archived sera samples were tested for HIV using the HIV ½ AG/AB 4TH GEN W/ REFLEXES.(19, 20) Men that were found to be HIV seropositive at their baseline visit were excluded from all analyses.
A full description of EGL specimen collection procedures has been published.(21, 22) Briefly, at each clinic visit, the genitals were examined under 3x light magnification by a trained clinician for the presence of EGLs. Lesions found within the perianal region were not included. For each EGL that appeared to be HPV-related or had an unknown etiology based on visual inspection, a tissue sample was obtained and confirmed to be HPV-related by a pathologist.
Blood and urine specimens were collected on a yearly basis. The sera were used to test for herpes simplex virus 2 (HSV2) and syphilis. The urine specimen was used to test for C. trachomatis and N. gonorrhea. A full description of laboratory testing has been published.(23)
Statistical methods
Sex was defined as oral, vaginal or anal sex. Using responses to questions at baseline and throughout follow-up, we defined men who have sex with men (MSM) as men having sex with a men irrespective of sex with women, and men who have sex with women (MSW) as men having sex with women only during their lifetime. One participant with no sexual intercourse throughout follow-up was excluded from analyses.
The exposure of interest was EGLs and prevalent and incident EGLs were included in the analysis up until the most recent archived visit with a collected blood sample. Follow-up time was from the baseline visit until either HIV seroconversion or the participant’s last archived blood specimen that was assessed for HIV.
We compared baseline demographic and behavioral characteristics between men with and without an EGL during follow-up using chi-squared tests for categorical variables and two-sample unpaired t-tests for continuous variables. Wilcoxon Rank Sum test was used to compare self-reported numbers of lifetime sexual partners because of outliers. Missing values for race for 20 participants were imputed based on the modal race for the participant’s clinic site. For questions about number of sexual partners, missing responses are interpreted as “none reported.”
Cox proportional hazards (PH) models assessed the association between EGLs and time to HIV seroconversion. Univariate models with hazard ratios (HR) and 95% confidence intervals (CI) were calculated. Due to the small number of observed HIV seroconversions, two propensity score models were used to calculate adjusted associations between EGLs and HIV seroconversion. For the first propensity score model, we fit a logistic regression model for EGL status during follow-up (ever EGL-positive or never EGL-positive) on time-independent covariates, computed the propensity for EGL, and then fit a Cox PH model assessing the association between EGL status (time-varying) and time to HIV seroconversion while directly adjusting for the propensity score as a covariate. Because the distribution of self-reported lifetime numbers of male and female sexual partners were skewed, these variables were square root transformed. This model allowed patients to switch from EGL-negative to EGL-positive, but EGL-positive status carried forward. For the second propensity score model among MSM, we fit a marginal structural model to allow for time-varying confounding by self-reported anal sexual positions between visits.(24) We first fit a pooled logistic regression for EGLs on time-independent, baseline covariates and time-dependent, reported sexual positions; patient-specific propensity scores for EGLs at each visit were then constructed. Propensity scores from a reduced logistic regression model (baseline covariates only) were used to create stabilized inverse probability weights that were used to weight a pooled logistic regression for HIV seroconversion based on time-varying EGL status. Confidence intervals were constructed using bootstrap quantiles. Sexual positions were categorized as reported both receptive and insertive, insertive only, receptive (with or without insertive), no anal sex, or missing anal sex information.
Results
Among the 1390 men that consented to having their archived serum specimens tested for HIV, 40 (3%) tested HIV-positive. Of those, 11 men were HIV seropositive at their enrollment visit and were excluded from analyses. Of the 1379 men included in analyses, 281 (20.4%) men were from USA, 584 (42.3%) from Brazil, and 514 (37.3%) from Mexico (Table 1). Compared to men without an EGL during follow-up, men with an EGL tended to have been followed for a slightly shorter period of time, were more likely to be MSW, have more lifetime female and more lifetime male sexual partners, and were more likely to be from Mexico. Among the 29 men that HIV seroconverted during follow-up, one was MSW and 28 were MSM. Participants that were positive for HSV-2 or Syphilis were significantly more likely to HIV seroconvert than participants that were negative. Only three participants had a gonorrhea infection and 79 had a chlamydia infection during follow-up; none of these participants HIV seroconverted.
Table 1.
Patient demographics by external genital lesion (EGL) status and HIV status (n=1379).
| EGL status | HIV status | |||||
|---|---|---|---|---|---|---|
| EGL-negative (n=974) |
EGL-positive (n=405) |
P* | HIV-negative (n=1350) |
HIV-positive (n=29) |
P* | |
| Age at baseline (mean, sd) | 35.54 (11.05) | 35.52 (10.45) | 0.97 | 35.64 (10.90) | 30.83 (8.64) | <0.01 |
| Days of follow up (mean, sd) | 2789 (676) | 2676 (759) | 0.01 | 2781 (673) | 1569 (995) | <0.01 |
| Clinic | <0.01 | <0.01 | ||||
| USA | 214 (22.0) | 67 (16.5) | 281 (20.8) | 0 (0.0) | ||
| Brazil | 464 (47.6) | 120 (29.6) | 560 (41.5) | 24 (82.8) | ||
| Mexico | 296 (30.4) | 218 (53.8) | 509 (37.7) | 5 (17.2) | ||
| Race | <0.01 | <0.01 | ||||
| White | 450 (46.2) | 126 (31.1) | 555 (41.1) | 21 (72.4) | ||
| Black | 185 (19.0) | 52 (12.8) | 235 (17.4) | 2 (6.9) | ||
| Other | 339 (34.8) | 227 (56.0) | 560 (41.5) | 6 (20.7) | ||
| Sexual orientation | <0.01 | <0.01 | ||||
| MSM | 394 (40.5) | 110 (27.2) | 476 (35.3) | 28 (96.6) | ||
| MSW | 580 (59.5) | 295 (72.8) | 874 (64.7) | 1 (3.4) | ||
| Lifetime sexual partners at baseline (median, IQR) | ||||||
| Female | 5 (1-15) | 8 (3-16) | <0.01 | 6 (2-15) | 1 (0-5) | <0.01 |
| Male | 0 (0-1) | 0 (0-0) | <0.01 | 0 (0-0) | 15 (1-30) | <0.01 |
| Anal sex position a,b | <0.01 | <0.01 | ||||
| No anal sex | 716 (73.5) | 333 (82.2) | 1046 (77.5) | 3 (10.3) | ||
| Insertive only | 124 (12.7) | 41 (10.1) | 156 (11.6) | 9 (31.0) | ||
| Receptive only | 18 (1.8) | 3 (0.7) | 19 (1.4) | 2 (6.9) | ||
| Insertive and receptive | 52 (5.3) | 13 (3.2) | 58 (4.3) | 7 (24.1) | ||
| Missing anal sex information | 64 (6.6) | 15 (3.7) | 71 (5.3) | 8 (27.6) | ||
| Syphilis b | 0.13 | <0.01 | ||||
| Negative | 954 (97.9) | 402 (99.3) | 1331 (98.6) | 25 (86.2) | ||
| Positive | 20 (2.1) | 3 (0.7) | 19 (1.4) | 4 (13.8) | ||
| HSV b | <0.01 | 0.51 | ||||
| Negative | 717 (73.6) | 330 (81.5) | 1027 (76.1) | 20 (69.0) | ||
| Positive | 257 (26.4) | 75 (18.5) | 323 (23.9) | 9 (31.0) | ||
| HIV seroconverted | 25 (2.6) | 4 (1.0) | 0.10 | |||
| EGL | 0.10 | |||||
| Negative | 949 (70.3) | 25 (86.2) | ||||
| Positive | 401 (29.7) | 4 (13.8) | ||||
Abbreviations: MSW: Men who have sex with only women; MSM: Men who have sex with men irrespective of sex with women
P values for categorical variables are from Pearson’s chi-squared tests and for continuous variables (excluding lifetime sexual partners) are from two-sample unpaired t-tests. Due to the skewed distribution of lifetime sexual partners at baseline, the P values for this variable are from Wilcoxon Rank-Sum tests.
Anal sex position and number of lifetime male partners for MSM only.
Baseline characteristic
After adjusting for race, age, sexual orientation, and lifetime numbers of female and male sexual partners at baseline in a propensity score analysis, participants with an EGL still had a non-significant lower hazard of HIV seroconversion compared to participants without an EGL (HR=0.94, 95%CI 0.32-2.74). When we restricted the analysis to MSM and further adjusted for reported anal sex position, results were largely similar (HR=0.63, 95%CI 0.00-1.86).
Discussion
We assessed the role of EGLs in HIV seroconversion risk among 1379 men living in USA, Brazil and Mexico with 2% of the participants seroconverting to HIV during follow-up. We found no significant difference in the risk of HIV seroconversion between men with and without EGLs in unadjusted or adjusted models, although the number of HIV seroconversions was low thereby limiting the power of our analyses. Stratified analyses among MSM also did not detect an association between EGLs and HIV seroconversion. While HPV infections in men appear to increase the risk for HIV acquisition, we did not find that HPV-related EGLs increased the risk for HIV.(10–12)
A cohort of 1427 MSM from Sydney, Australia, found that self-reported EGLs significantly increased the risk for HIV seroconversion among MSM in univariate analysis, but this association did not remain significant after adjusting for sexually transmitted infections and serodiscordant unprotected anal intercourse.(25) In their cohort, there were 74 (5%) men that self-reported EGLs and only three HIV seroconverted during follow-up.(25) We examined men every six-months for EGLs and removed the lesion entirely or provided topical treatment. Many of the EGLs were identified while the lesions were very small, and it is possible that because of the early treatment, and reduced time to self-resolve the EGLs, an association between EGLs and risk for HIV seroconversion was not detected.
The few studies conducted among women and men consistently demonstrate increased risk of HIV with prior anogenital HPV infection. Results from a meta-analysis among women in Africa (6–9) demonstrated that HPV infection increases risk of HIV acquisition twofold.(3) Anal HPV infection was associated with a two- to threefold increase in HIV acquisition among U.S. MSM,(10) and genital HPV infection was associated with a similarly elevated HIV risk among African men.(11, 12) While HPV infection may predispose women and men to HIV, an effective immune response to HPV infection (i.e., clearance of the infection) may confer the greatest risk of HIV acquisition, (6–12) with genital HPV clearance shown to be associated with increased risk of HIV seroconversion.(11, 12) These results are compelling and suggest that elimination of HPV through vaccination may decrease HIV risk.
This study has several strengths including the large sample size, duration of follow-up, and data collection from three international clinical sites. Data collection and specimen processing were consistent across the three clinical sites. Participants’ genitals were examined at every 6-month visit and any EGL suspicious for HPV was removed and reviewed by pathology. EGLs included in this analysis were all HPV-related and histologically confirmed. HIV seroconversion was also measured from archived serum specimens that provided a six-month time window for when HIV seroconversion occurred. We adjusted for baseline lifetime partners, but recent sexual behavior could also be associated with HIV risk. We were limited in our analyses based on the small number of men that HIV seroconverted: only one MSW and 28 MSM seroconversions.
In conclusion, we did not find any difference in HIV seroconversion between men with and without EGL in a multinational cohort. Our statistical power was limited as few men HIV seroconverted. Results may differ in populations at higher risk for HIV.
Acknowledgements
This research was supported in part by research funding from Merck Sharp & Dohme Corp. The opinions expressed in this paper are those of the authors and do not necessarily represent those of Merck Sharp & Dohme Corp.
Special thanks to the men who provided personal information and biological specimens for the study. Thanks to the HPV Infection in Men (HIM) Study Team in São Paulo, Cuernavaca, and Tampa.
Funding:
The HIM Study infrastructure was supported by the National Cancer Institute, National Institutes of Health [R01 CA098803 to A.R.G.]. Dr. Sudenga (K07 CA225404) is supported by the National Cancer Institute. National Institute of Allergy and Infectious Disease [R03 AI127205 to S.L.S] and Merck Investigator Initiated Studies Program (IISP53280 to S.L.S.) provided funding for this project.
Conflicts of Interest:
A.R.G., L.L.V., and E.L.P. are members of the Merck Advisory Board. S.L.S. received a grant (IISP53280) from Merck Investigator Initiated Studies Program. No conflicts of interest were declared for any of the remaining authors.
Footnotes
Presentation in part: 31st International Papillomavirus Conference, Cape Town, South Africa, March 2017.
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