Longitudinal community plasma HIV-1 RNA concentrations and incidence of HIV-1 among injecting drug users: prospective cohort study

doi:10.1136/bmj.b1649

Published 30 April 2009, doi:10.1136/bmj.b1649
Cite this as: BMJ 2009;338:b1649

Research

Longitudinal community plasma HIV-1 RNA concentrations and incidence of HIV-1 among injecting drug users: prospective cohort study

Evan Wood, research scientist¹, Thomas Kerr, research scientist¹, Brandon D L Marshall, PhD candidate², Kathy Li, senior statistician¹, Ruth Zhang, statistician¹, Robert S Hogg, director, HIV/AIDS drug treatment program¹, P Richard Harrigan, director, research laboratories¹, Julio S G Montaner, head³

¹ British Columbia Centre for Excellence in HIV/AIDS, Vancouver, Canada, ² School of Population and Public Health, University of British Columbia, Vancouver, ³ Division of AIDS, Department of Medicine, University of British Columbia, Vancouver

Correspondence to: E Wood uhri-ew{at}cfenet.ubc.ca

Objective To examine the relation between plasma HIV-1 RNA concentrationsin the community and HIV incidence among injecting drug users.

Design Prospective cohort study.

Setting Inner city community in Vancouver, Canada.

Participants Injecting drug users, with and without HIV, followedup every six months between 1 May 1996 and 30 June 2007.

Main outcome measures Estimated community plasma HIV-1 RNA inthe six months before each HIV negative participant’sfollow-up visit. Associated HIV incidence.

Results Among 622 injecting drug users with HIV, 12 435 measurementsof plasma HIV-1 RNA were obtained. Among 1429 injecting drugusers without HIV, there were 155 HIV seroconversions, resultingin an incidence density of 2.49 (95% confidence interval 2.09to 2.88) per 100 person years. In a Cox model that adjustedfor unsafe sexual behaviours and sharing used syringes, theestimated community plasma HIV-1 RNA concentration remainedindependently associated with the time to HIV seroconversion(hazard ratio 3.32 (1.82 to 6.08, P<0.001), per log₁₀ increase).When the follow-up period was limited to observations after1 January 1988 (when the median plasma HIV RNA concentrationwas <20 000 copies/ml), the median viral load was no longerstatistically associated with HIV incidence (1.70 (0.79 to 3.67,P=0.175), per log₁₀ increase).

Conclusions A longitudinal measure of community plasma HIV-1RNA concentration was correlated with the community HIV incidencerate and predicted HIV incidence independent of unsafe sexualbehaviours and sharing used syringes. If these findings areconfirmed, they could help to inform both HIV prevention andtreatment interventions.

© Wood et al 2009
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Add to CiteULike CiteULike Add to Complore Complore Add to Connotea Connotea Add to Del.icio.us Del.icio.us Add to Digg Digg Add to Reddit Reddit Add to StumbleUpon StumbleUpon Add to Technorati Technorati What's this?

This article has been cited by other articles:

Fauci, A. S., Folkers, G. K. (2009). Investing To Meet The Scientific Challenges Of HIV/AIDS. Health Aff (Millwood) 28: 1629-1641 [Abstract] [Full text]
DeBeck, K., Kerr, T., Li, K., Fischer, B., Buxton, J., Montaner, J., Wood, E. (2009). Smoking of crack cocaine as a risk factor for HIV infection among people who use injection drugs. CMAJ 181: 585-589 [Abstract] [Full text]