Elevated vaginal pH at the time of cervical intraepithelial neoplasia 2 diagnosis may be a useful marker of CIN 2 persistence/progression, as well as the rate of persistence/progression in HIV-positive women, new research suggests.
“We analyzed data from the Women’s Interagency HIV Study [WIHS], an observational, longitudinal cohort of women with and without HIV to determine factors that may influence CIN 2 natural history,” said Kate Michel, PhD, MPH, of Georgetown University, Washington. She presented the results at the Conference on Retroviruses and Opportunistic Infections.
As previous data have shown a high incidence of CIN 2 progression among women with HIV, the researchers evaluated the role of human papillomavirus (HPV) type, local immune response, and markers of the cervicovaginal microbiome on the risk of CIN 2 persistence/progression.
Within the cohort, follow-up visits occur every 6 months, and clinical data is collected via questionnaires, physical and gynecologic exams, and biological samples. As no specific treatment is offered in the WIHS, treatment for cervical abnormalities is abstracted from medical records.
In the present study, Dr. Michel and colleagues selected up to four banked cervicovaginal lavage (CVL) samples per woman, with the first sample selected 6-12 months prior to CIN 2 diagnosis, the second at CIN 2 diagnosis, the third between CIN 2 diagnosis and outcome, and the fourth at the outcome visit.
The investigators performed HPV typing and muiltiplex immune mediator testing on each CVL sample. Lab results from WIHS core testing were also extracted, including plasma CD4+ T-cell count and HIV viral load, as well as vaginal pH and Nugent’s score.
Study outcomes included persistence/progression and regression, defined as a subsequent CIN 2 or CIN 3 diagnosis and subsequent CIN 1 or normal diagnosis, respectively. Logistic regression models were used to determine CIN 2 regression versus persistence/progression.
A total of 337 samples were obtained and 94 women were included in the analysis. Key demographic and behavioral factor were similar at CIN 2 diagnosis.
The majority of participants were African American (53.2%) and on antiretroviral therapy (66.0%). The most prevalent high-risk types were HPV-58 (18.4%) and HPV-16 (17.5%).
After a median 12.5 years of follow-up, 33 participants (35.1%) with incident CIN 2 had a subsequent CIN 2/CIN 3 diagnosis and those who regressed had a higher CD4 T-cell count at CIN 2 diagnosis (P = .02).
Each subsequent high-risk HPV type identified at the pre–CIN 2 visit was associated with higher odds of CIN2 persistence/progression (odds ratio, 2.27; 95% confidence interval, 1.15-4.50).
Bacterial vaginosis (adjusted OR, 5.08; 95% CI, 1.30-19.94) and vaginal pH (aOR, 2.27; 95% CI, 1.15-4.50) at the CIN 2 diagnosis visit were each associated with increased odds of CIN 2 persistence/progression.
Vaginal pH greater than 4.5 at CIN 2 diagnosis was also associated with unadjusted time to CIN 2 persistence/progression (log rank P = .002) and an increased rate of CIN 2 persistence/progression (adjusted hazard ratio, 3.37; 95% CI, 1.26-8.99).
Furthermore, among participants who did not receive CIN 2 treatment, vaginal pH remained associated with greater odds of CIN 2 persistence/progression (OR, 2.46; 95% CI, 1.19-5.13). Cervicovaginal immune mediator levels were not associated with CIN 2 persistence/progression.
“The most striking finding from this work was that vaginal pH was associated with higher odds of, quicker time to, and increased hazard of CIN 2 persistence/progression,” Dr. Michel said. “We postulate this effect is mediated by the cervical microbiome, but more work is needed to establish the exact mechanism.”
“It would be interesting to test whether this association might be explained by different vaginal cleaning techniques, such as douching,” said moderator, of the University of California, Los Angeles.
“We’re currently working on an analysis of cervicovaginal bacterial species to explore the microbiome in more detail,” Dr. Michel concluded.
Dr. Michel disclosed no conflicts of interest. The study was supported by multiple sources, including the National Institute of Allergy and Infectious Diseases, the National Cancer Institute, and the Georgetown-Howard Universities Center for Clinical and Translational Science.