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Transmission of HIV drug resistance increases among illegal drug users in Vancouver
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The prevalence of transmitted drug resistance in people with HIV who were using illegal drugs increased significantly over a 20-year period in Vancouver, British Columbia, researchers wrote in Clinical Infectious Diseases.
“Our findings support baseline resistance testing early in the course of HIV infection to guide ART selection among people who use illegal drugs (PWUD) in our setting,” they wrote.
The researchers gathered data from two prospective cohorts of PWUD in the area — the AIDS Care Cohort to Evaluate Exposure to Survival Services (ACCESS), which involved patients without HIV; and the Vancouver Injection Drug Users Study (VIDUS), which included those with the virus. The data spanned the period of 1996 to 2015.
Participants in both studies were recruited via street outreach and snowball sampling in the Vancouver area, and researchers focused on the city’s downtown Eastside neighborhood, because of the prevalence of drug use, poverty and HIV infection there. VIDUS participants who seroconverted during follow-up became candidates for the current study.
The study included 573 PWUD with HIV who had undergone at least one genotypic test for drug resistance before starting ART.
The median patient age was 37 years, 370 (64.6%) patients were male, 545 (95.1%) had a history of injection drug use and 101 (17.6%) had a documented recent HIV infection, the researchers wrote.
Overall, 56 (9.8%) patients had transmitted drug resistance (TDR), and three (0.5%) had dual-class TDR. The prevalence of TDR was significantly lower among PWUD recently infected with HIV (adjusted OR = 0.39; 95% CI, 0.15-0.87) and among those with a viral load of more than 5 log10 copies/mL (aOR = 0.47; 95% CI, 0.25-0.83).
Over the entire 20-year study period, the prevalence of TDR initially decreased, but then sharply increased. It dropped from 8.5% in 1996 to 1999 to 4.8% in 2000 to 2005, then rose to 10.6% in 2006 to 2009, and again to 21.1% in 2010 to 2015 (P = .003).
Increases in TDR to nonnucleoside reverse transcriptase inhibitors (NNRTIs) were the main drivers of the overall TDR increase over time, the researchers wrote. NNRTI TDR prevalence rose from 1.6% in 1996 to 1999, to 14.1% in 2010 to 2015 (P < .001). The prevalence of TDR to protease inhibitors and nucleoside reverse transcriptase inhibitors had no statistically significant changes.
Although they stressed a need for baseline TDR testing, the researchers also recommended broadening outreach beyond known HIV cases.
“Our findings underscore the importance of universal HIV testing and rapid linkage to care and ART initiation among newly diagnosed HIV-positive PWUD to limit the spread of TDR,” they wrote. – by Joe Green
Disclosure: Please see the full study for a list of all other authors’ relevant financial disclosures.
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