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. 2009 Apr 30:338:b1649.
doi: 10.1136/bmj.b1649.

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

Evan Wood  1 , Thomas Kerr, Brandon D L Marshall, Kathy Li, Ruth Zhang, Robert S Hogg, P Richard Harrigan, Julio S G Montaner
Affiliations

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

Evan Wood et al. BMJ. .

Abstract

Objective: To examine the relation between plasma HIV-1 RNA concentrations in 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, followed up every six months between 1 May 1996 and 30 June 2007.

Main outcome measures: Estimated community plasma HIV-1 RNA in the six months before each HIV negative participant's follow-up visit. Associated HIV incidence.

Results: Among 622 injecting drug users with HIV, 12 435 measurements of plasma HIV-1 RNA were obtained. Among 1429 injecting drug users without HIV, there were 155 HIV seroconversions, resulting in an incidence density of 2.49 (95% confidence interval 2.09 to 2.88) per 100 person years. In a Cox model that adjusted for unsafe sexual behaviours and sharing used syringes, the estimated community plasma HIV-1 RNA concentration remained independently associated with the time to HIV seroconversion (hazard ratio 3.32 (1.82 to 6.08, P<0.001), per log(10) increase). When the follow-up period was limited to observations after 1 January 1988 (when the median plasma HIV RNA concentration was <20 000 copies/ml), the median viral load was no longer statistically associated with HIV incidence (1.70 (0.79 to 3.67, P=0.175), per log(10) increase).

Conclusions: A longitudinal measure of community plasma HIV-1 RNA concentration was correlated with the community HIV incidence rate and predicted HIV incidence independent of unsafe sexual behaviours and sharing used syringes. If these findings are confirmed, they could help to inform both HIV prevention and treatment interventions.

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Conflict of interest statement

Competing interests: RSH has received funding for research and continuing medical education programmes from pharmaceutical companies, including Abbott, Boehringer Ingelheim, and GlaxoSmithKline. JSGM has received educational grants from, served as an ad hoc adviser to, or spoken at various events sponsored by Abbott Laboratories, Agouron Pharmaceuticals, Boehringer Ingelheim Pharmaceuticals, Borean Pharma AS, Bristol-Myers Squibb, DuPont Pharma, Gilead Sciences, GlaxoSmithKline, Hoffmann-La Roche, Immune Response Corporation, Incyte, Janssen-Ortho, Kucera Pharmaceutical Company, Merck Frosst Laboratories, Pfizer Canada, Sanofi Pasteur, Shire Biochem, Tibotec Pharmaceuticals, and Trimeris.

Ethical approval: The research was approved by the University of British Columbia’s research ethics board at St Paul’s Hospital.

Figures

None
Estimated community plasma HIV-1 RNA concentrations and HIV incidence density, with 95% confidence intervals, among two parallel cohorts of injecting drug users. HIV incidence first estimated in second half of 1996 as enrolment started in May 1996 and repeat HIV tests to assess incidence were available only after six months of follow-up
See this image and copyright information in PMC

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