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Association between intravaginal practices and HIV acquisition in women: individual patient data meta-analysis of cohort studies in sub-Saharan Africa
Presented by Matthew Francis Chersich (South Africa).
M.F. Chersich1,2, A. Martin Hilber3, K. Schmidlin3, M. Egger3, S. Francis4, J. Baeten5, J. Brown6, S. Delany-Moretlwe1, R. Hayes4, R. Kaul7, S. Luchters8, N. McGrath4,9, L. Myer10, H. Rees1, M. Temmerman8, A. Van der Straten11, J. Van de Wijgert12, D. Watson-Jones4, M. Zwahlen3, N. Low3
1Reproductive Health and HIV Research Unit, University of the Witwatersrand, Department of Obstetrics and Gynaecology, Johannesburg, South Africa, 2International Centre for Reproductive Health, Mombasa, Kenya, 3Institute of Social & Preventive Medicine, Bern, Switzerland, 4London School of Hygiene & Tropical Medicine, London, United Kingdom, 5University of Washington, Departments of Global Health and Medicine, Seattle, United States, 6University of North Carolina, North Carolina, United States, 7University of Toronto, Toronto, Canada, 8International Centre for Reproductive Health, Gent, Belgium, 9Africa Centre for Health and Population Studies, University of KwaZulu-Natal, Durban, South Africa, 10University of Cape Town, Cape Town, South Africa, 11Women's Global Health Imperative, UCSF, RTI International and Department of Medicine, California, United States, 12Center for Poverty-related Communicable Diseases, Academic Medical Center, Amsterdam, Netherlands
Background: It is still not clear whether practices such as internal (intravaginal) cleansing and practices used around sexual intercourse, increase women's risk of acquiring HIV infection. Individual studies lack statistical power and direct comparison between studies is hampered by variation in exposure definitions and statistical methods.
Methods: A systematic review identified 14 cohort studies in sub-Saharan Africa that measured HIV as an outcome and collected data on vaginal practices; 11 provided individual patient data, and 9 have been analysed to date. We recoded data using standardised definitions of any vaginal practice, intravaginal cleansing, insertion of solid products, and use of products to dry or tighten the vagina. We used univariable Cox proportional hazards models, stratified by study, to examine the association between the use of practices as reported at study baseline and HIV acquisition.
Results: A total of 14,766 women contributed 24,587 woman years, with 798 newly-acquired HIV infections. The prevalence of any vaginal practice across cohorts ranged from 18% to 95% (median 76%); intravaginal cleansing was reported by a median of 70% of women (range 7-94%). In univariable analysis, women reporting any vaginal practice had a 1.27 fold higher rate of HIV acquisition (95%CI 0.91-1.77) than never-users, with moderate between-study heterogeneity (I246%). Compared with never-users, hazard ratios for incident HIV in women with different practices were: water only, 1.07 (95%CI 0.83-1.38); other products for intravaginal cleansing, 1.44 (95%CI 1.16-1.79); and practices other than intravaginal cleansing, 1.88 (95%CI 1.25-2.82)
Conclusions: Intravaginal practices are common in sub-Saharan Africa. These may increase women's risk of acquiring HIV, particularly practices other than cleansing with water. Additional analyses will clarify the role of confounding in these associations. Common practices that increase HIV risk may also reduce the effectiveness of vaginal microbicides. Interventions to alter potentially harmful intravaginal practices might contribute to combination HIV prevention.
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