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      Intravaginal Practices, Bacterial Vaginosis, and HIV Infection in Women: Individual Participant Data Meta-analysis

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          Pooling of data from 14,874 women in an individual participant data meta-analysis by Nicola Low and colleagues reveals that some intravaginal practices increase the risk of HIV acquisition.



          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.

          Methods and Findings

          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.


          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

          Editors' Summary


          Since the first reported case of acquired immunodeficiency syndrome (AIDS) in 1981, the number of people infected with the human immunodeficiency virus (HIV), which causes AIDS, has risen steadily. By the end of 2009, an estimated 33.3 million people were living with HIV/AIDS. At the beginning of the epidemic, more men than women were infected with HIV but now, globally, more than half of all adults living with HIV/AIDS are women, and HIV/AIDS is the leading cause of death among women of child-bearing age. In sub-Saharan Africa, where more than two-thirds of HIV-positive people live, the situation for women is particularly bad. About 12 million women live with HIV/AIDS in this region compared with about 8 million men; among 15–24 year-olds, women are eight times more likely than men to be HIV-positive. This pattern of infection has developed because in sub-Saharan Africa most people contract HIV through heterosexual sex.

          Why Was This Study Done?

          If modifiable factors that increase women's vulnerability to HIV infection could be identified, it might be possible to develop effective female-initiated prevention interventions. Some experts think that intravaginal practices such as cleaning the vagina with soap or a cloth increase the risk of HIV infection by damaging the vagina's lining or by increasing bacterial vaginosis (a condition in which harmful bacteria disrupt the healthy vaginal flora) but the evidence for such an association is inconclusive. In this meta-analysis, the researchers pool individual participant data from several prospective longitudinal cohort studies to assess the association between intravaginal practices and HIV acquisition among women in sub-Saharan Africa. Meta-analysis is a statistical method that combines data from several studies to get a clearer view of the factors associated with of a disease than is possible from individual studies. In a prospective longitudinal cohort study, groups of participants with different baseline characteristics (here, women who did or did not use intravaginal practices), who do not have the outcome of interest at the start of the study (here, HIV infection) are followed to see whether these characteristics affect disease development.

          What Did the Researchers Do and Find?

          The researchers pooled individual participant data from 13 prospective cohort studies in sub-Saharan Africa involving nearly 15,000 women, 791 of whom acquired HIV, and asked whether HIV infection within 2 years of study enrollment was associated with self-reported intravaginal practices. That is, were women who used specific intravaginal practices more likely to become infected with HIV than women who did not use these practices? After controlling for age, marital status, and the number of recent sex partners, women who used cloth or paper to clean their vagina were nearly one and half times more likely to have acquired HIV infection as women who did not use this practice (a pooled adjusted hazard ratio [aHR] of 1.47). The insertion of products to dry or tighten the vagina and intravaginal cleaning with soap also increased women's chances of acquiring HIV (aHRs of 1.31 and 1.24, respectively). Moreover, intravaginal cleaning with soap was associated with the development of bacterial vaginosis, and disrupted vaginal flora and bacterial vaginosis were both associated with an increased risk of HIV acquisition.

          What Do These Findings Mean?

          These findings suggest that some intravaginal practices increase the risk of HIV acquisition but they do not prove that there is a causal link between any intravaginal practice, disruption of vaginal flora, and HIV acquisition. It could be that the women who use intravaginal practices share other unknown characteristics that affect their vulnerability to HIV infection. The accuracy of these findings is also likely to be affected by the use of self-reported data and inconsistent definitions of intravaginal practices. Nevertheless, given the widespread use of intravaginal practices in some sub-Saharan countries (95% of female sex workers in Kenya use such practices, for example), these findings suggest that encouraging women to use less harmful intravaginal practices (for example, washing with water alone) should be included in female-initiated HIV prevention research strategies in sub-Saharan Africa and other regions where intravaginal practices are common.

          Additional Information

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          Most cited references 36

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          Nonspecific vaginitis. Diagnostic criteria and microbial and epidemiologic associations.

          Numerous previous studies of nonspecific vaginitis have yielded contradictory results regarding its cause and clinical manifestations, due to a lack of uniform case definition and laboratory methods. We studied 397 consecutive unselected female university students and applied sets of well defined criteria to distinguish nonspecific vaginitis from other forms of vaginitis and from normal findings. Using such criteria, we diagnosed nonspecific vaginitis in up to 25 percent of our study population; asymptomatic disease was recognized in more than 50 percent of those with nonspecific vaginitis. A clinical diagnosis of nonspecific vaginitis, based on simple office procedures, was correlated with both the presence and the concentration of Gardnerella vaginalis (Hemophilus vaginalis) in vaginal discharge, and with characteristic biochemical findings in vaginal discharge. Nonspecific vaginitis was also correlated with a history of sexual activity, a history of previous trichomoniasis, current use of nonbarrier contraceptive methods, and, particularly, use of an intrauterine device. G. vaginalis was isolated from 51.3 percent of the total population using a highly selective medium that detected the organism in lower concentration in vaginal discharge than did previously used media. Practical diagnostic criteria for standard clinical use are proposed. Application of such criteria should assist in clinical management of nonspecific vaginitis and in further study of the microbiologic and biochemical correlates and the pathogenesis of this mild but quite prevalent disease.
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            Bacterial vaginosis and disturbances of vaginal flora: association with increased acquisition of HIV.

            Cross-sectional studies suggest an association between bacterial vaginosis (BV) and HIV-1 infection. However, an assessment of a temporal effect was not possible. To determine the association of BV and other disturbances of vaginal flora with HIV seroconversion among pregnant and postnatal women in Malawi, Africa. Longitudinal follow-up of pregnant and postpartum women. Women attending their first antenatal care visit were screened for HIV after counselling and obtaining informed consent. HIV-seronegative women were enrolled and followed during pregnancy and after delivery. These women were again tested for HIV at delivery and at 6-monthly visits postnatally. Clinical examinations and collection of laboratory specimens (for BV and sexually transmitted diseases) were conducted at screening and at the postnatal 6-monthly visits. The diagnosis of BV was based on clinical criteria. Associations of BV and other risk factors with HIV seroconversion, were examined using contingency tables and multiple logistic regression analyses on antenatal data, and Kaplan-Meier proportional hazards analyses on postnatal data. Among 1196 HIV-seronegative women who were followed antenatally for a median of 3.4 months, 27 women seroconverted by time of delivery. Postnatally, 97 seroconversions occurred among 1169 seronegative women who were followed for a median of 2.5 years. Bacterial vaginosis was significantly associated with antenatal HIV seroconversion (adjusted odds ratio = 3.7) and postnatal HIV seroconversion (adjusted rate ratio = 2.3). There was a significant trend of increased risk of HIV seroconversion with increasing severity of vaginal disturbance among both antenatal and postnatal women. The approximate attributable risk of BV alone was 23% for antenatal HIV seroconversions and 14% for postnatal seroconversions. This prospective study suggests that progressively greater disturbances of vaginal flora, increase HIV acquisition during pregnancy and postnatally. The screening and treating of women with BV could restore normal flora and reduce their susceptibility to HIV.
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              Meta-analysis of individual patient data from randomized trials: a review of methods used in practice.

              Meta-analyses based on individual patient data (IPD) are regarded as the gold standard for systematic reviews. However, the methods used for analysing and presenting results from IPD meta-analyses have received little discussion. We review 44 IPD meta-analyses published during the years 1999-2001. We summarize whether they obtained all the data they sought, what types of approaches were used in the analysis, including assumptions of common or random effects, and how they examined the effects of covariates. Twenty-four out of 44 analyses focused on time-to-event outcomes, and most analyses (28) estimated treatment effects within each trial and then combined the results assuming a common treatment effect across trials. Three analyses failed to stratify by trial, analysing the data is if they came from a single mega-trial. Only nine analyses used random effects methods. Covariate-treatment interactions were generally investigated by subgrouping patients. Seven of the meta-analyses included data from less than 80% of the randomized patients sought, but did not address the resulting potential biases. Although IPD meta-analyses have many advantages in assessing the effects of health care, there are several aspects that could be further developed to make fuller use of the potential of these time-consuming projects. In particular, IPD could be used to more fully investigate the influence of covariates on heterogeneity of treatment effects, both within and between trials. The impact of heterogeneity, or use of random effects, are seldom discussed. There is thus considerable scope for enhancing the methods of analysis and presentation of IPD meta-analysis.

                Author and article information

                Role: Academic Editor
                PLoS Med
                PLoS Medicine
                Public Library of Science (San Francisco, USA )
                February 2011
                February 2011
                15 February 2011
                : 8
                : 2
                [1 ]Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
                [2 ]Centre for Health Policy, School of Public Health, University of Witwatersrand, Johannesburg, South Africa
                [3 ]International Centre for Reproductive Health, Department of Obstetrics and Gynaecology, Ghent University, Ghent, Belgium
                [4 ]Department of Infectious Disease Epidemiology and Clinical Research, London School of Hygiene and Tropical Medicine, London, United Kingdom
                [5 ]Academic Medical Center of the University of Amsterdam and Amsterdam Institute for Global Health and Development, Amsterdam, The Netherlands
                [6 ]Departments of Global Health, Medicine, and Epidemiology, University of Washington, Seattle, Washington, United States of America
                [7 ]Department of Epidemiology, University of California, Los Angeles, California, United States of America
                [8 ]Reproductive Health and HIV Research Unit, University of Witwatersrand, Hillbrow, South Africa
                [9 ]Department of Medicine, University of Toronto, Toronto, Canada
                [10 ]Africa Centre for Health and Population Studies, University of Kwa-Zulu Natal, Somkhele, South Africa
                [11 ]Clinical Sciences Department, FHI, Research Triangle Park, North Carolina, United States of America
                [12 ]Centre for Infectious Diseases Epidemiology and Research, School of Public Health & Family Medicine, University of Cape Town, Cape Town, South Africa
                [13 ]Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, United States of America
                [14 ]Women's Global Health Imperative, RTI International, San Francisco, California, United States of America
                National Institute of Child Health and Human Development, United States of America
                Author notes

                ICMJE criteria for authorship read and met: NL MFC KS ME SCF JHHMvdW RJH JMB JB SDM RK NM CM LM MT AvdS DWJ MZ AMH. Agree with the manuscript's results and conclusions: NL MFC KS ME SCF JHHMvdW RJH JMB JB SDM RK NM CM LM MT AvdS DWJ MZ AMH. Designed the experiments/the study: NL MFC ME SCF RJH DWJ AMH. Analyzed the data: NL KS RJH AMH. Collected data/did experiments for the study: MFC JHHMvdW RJH JMB JB SDM RK NM CM LM MT AvdS DWJ AMH. Enrolled patients: JMB JB SDM RK NM CM LM DWJ. Wrote the first draft of the paper: NL. Contributed to the writing of the paper: ME SCF JHHMvdW RJH JMB JB RK NM CM LM MT AvdS DWJ MZ AMH. The contributions to the study of these authors was equivalent. Data management, deriving of study variables: MFC. Contributed data to the individual participant data analysis: SCF. Helped to develop the statistical models and reviewed analysis output: JHHMvdW. Contributed to data and analysis interpretation: JMB. Was the Principal Investigator on one of the component studies in the meta-analysis: CM. Advised on how to conduct the statistical analysis: MZ. Coordinated the colloboration between all included partners and was a PI on the project; contributed to the intrepreptation of results with the analytical team: AMH.

                ¶ These authors are joint first authors on this work.

                Low et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
                Page count
                Pages: 14
                Research Article
                Infectious Diseases/HIV Infection and AIDS
                Public Health and Epidemiology/Epidemiology
                Public Health and Epidemiology/Infectious Diseases
                Women's Health/Gynecologic Inflammation and Infections
                Women's Health/Sexually Transmitted Diseases



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