title: Intravaginal practices, bacterial vaginosis, and HIV infection in women: individual participant data meta-analysis.
abstract: BACKGROUND
  Identifying modifiable factors that increase women's vulnerability to HIV is a critical step in developing effective female-initiated prevention interventions. The primary objective of this study was to pool individual participant data from prospective longitudinal studies to investigate the association between intravaginal practices and acquisition of HIV infection among women in sub-Saharan Africa. Secondary objectives were to investigate associations between intravaginal practices and disrupted vaginal flora; and between disrupted vaginal flora and HIV acquisition.
  
  
  RESULTS
  We conducted a meta-analysis of individual participant data from 13 prospective cohort studies involving 14,874 women, of whom 791 acquired HIV infection during 21,218 woman years of follow-up. Data were pooled using random-effects meta-analysis. The level of between-study heterogeneity was low in all analyses (I(2) values 0.0%-16.1%). Intravaginal use of cloth or paper (pooled adjusted hazard ratio [aHR] 1.47, 95% confidence interval [CI] 1.18-1.83), insertion of products to dry or tighten the vagina (aHR 1.31, 95% CI 1.00-1.71), and intravaginal cleaning with soap (aHR 1.24, 95% CI 1.01-1.53) remained associated with HIV acquisition after controlling for age, marital status, and number of sex partners in the past 3 months. Intravaginal cleaning with soap was also associated with the development of intermediate vaginal flora and bacterial vaginosis in women with normal vaginal flora at baseline (pooled adjusted odds ratio [OR] 1.24, 95% CI 1.04-1.47). Use of cloth or paper was not associated with the development of disrupted vaginal flora. Intermediate vaginal flora and bacterial vaginosis were each associated with HIV acquisition in multivariable models when measured at baseline (aHR 1.54 and 1.69, p<0.001) or at the visit before the estimated date of HIV infection (aHR 1.41 and 1.53, p<0.001), respectively.
  
  
  CONCLUSIONS
  This study provides evidence to suggest that some intravaginal practices increase the risk of HIV acquisition but a direct causal pathway linking intravaginal cleaning with soap, disruption of vaginal flora, and HIV acquisition has not yet been demonstrated. More consistency in the definition and measurement of specific intravaginal practices is warranted so that the effects of specific intravaginal practices and products can be further elucidated. Please see later in the article for the Editors' Summary.
authors.affiliation: Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland. low@ispm.unibe.ch
authors.forename: Nicola
authors.initials: N
authors.lastname: Low
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Chersich
authors.forename: Kurt
authors.initials: K
authors.lastname: Schmidlin
authors.forename: Matthias
authors.initials: M
authors.lastname: Egger
authors.forename: Suzanna C
authors.initials: SC
authors.lastname: Francis
authors.forename: Janneke H H M
authors.initials: JH
authors.lastname: van de Wijgert
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Hayes
authors.forename: Jared M
authors.initials: JM
authors.lastname: Baeten
authors.forename: Joelle
authors.initials: J
authors.lastname: Brown
authors.forename: Sinead
authors.initials: S
authors.lastname: Delany-Moretlwe
authors.forename: Rupert
authors.initials: R
authors.lastname: Kaul
authors.forename: Nuala
authors.initials: N
authors.lastname: McGrath
authors.forename: Charles
authors.initials: C
authors.lastname: Morrison
authors.forename: Landon
authors.initials: L
authors.lastname: Myer
authors.forename: Marleen
authors.initials: M
authors.lastname: Temmerman
authors.forename: Ariane
authors.initials: A
authors.lastname: van der Straten
authors.forename: Deborah
authors.initials: D
authors.lastname: Watson-Jones
authors.forename: Marcel
authors.initials: M
authors.lastname: Zwahlen
authors.forename: Adriane Martin
authors.initials: AM
authors.lastname: Hilber
mesh_terms: D017954:Africa South of the Sahara / Q000453:epidemiology; D005260:Female; D015658:HIV Infections / Q000453:epidemiology*; D006801:Humans; D044364:Vaginal Douching / Q000009:adverse effects; D016585:Vaginosis, Bacterial / Q000453:epidemiology*