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  Conference on Retroviruses
and Opportunistic Infections (CROI)
February 22-25, 2016, Boston MA
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Under Half in US Analysis Get Resistance Testing at Linkage to Care
  Conference on Retroviruses and Opportunistic Infections (CROI), February 22-25, 2016, Boston
Mark Mascolini
Only 45% of HIV-positive people linked to care in a US study got resistance testing within a month of linkage, as recommended by the Department of Health and Human Services [1]. This Centers for Disease Control and Prevention (CDC) analysis found that men who inject drugs have a significantly lower chance of getting tested for resistance mutations, as do women infected heterosexually.
US HIV care guidelines stipulate that everyone should get tested for resistance mutations when they enter care. Because little is known about whether US providers follow that advice, and which factors may favor or disfavor resistance testing, they conducted this analysis of 11,351 adults and adolescents diagnosed with HIV infection in 2013. In that group, 9481 people (83.5%) got linked to care within 3 months of diagnosis. The CDC team calculated both proportions who received resistance testing at any point and, among those tested, the proportion tested at linkage to care.
Among the 9481 people linked to care, 6181 (65%) got a resistance test at some point. Among those 6181, only 4270 get tested within 1 month of entering care (69% of the 6181 tested, 45% of the 9481 linked to care, and 38% of the 11,351 diagnosed with HIV). Neither age nor race had a big impact on rates of any resistance testing or resistance testing at linkage to care. But HIV transmission risk did make a difference. Among men infected while injecting drugs, only 58% had any resistance testing and only 62% got tested at linkage. For comparison, among men who have sex with men (MSM), rates of any testing and testing at linkage were 67% and 70%.
Among the jurisdictions analyzed, resistance testing at linkage proved less frequent in Los Angeles County (64%), Washington State (62%), and South Carolina (45%) than in Michigan, New York, or Texas (all 70% or higher). Any resistance testing was less frequent in areas with fewer than 0.5 million people (57%) than in regions with 0.5 to 2.5 million people (62%) or more than 2.5 million people (68%).
Multivariate analysis identified four factors that independently predicted a lower chance of any resistance testing, at the following adjusted prevalence ratios (aPR) (and 95% confidence intervals):
-- Men who inject drugs (compared with MSM): aPR 0.87 (0.80 to 0.96)
-- Heterosexually infected women (compared with MSM): aPR 0.92 (0.88 to 0.96)
-- Area with <0.5 million people (vs >2.5 million): aPR 0.89 (0.84 to 0.93)
-- Area with 0.5 to 2.5 million people (vs >2.5 million): aPR 0.95 (0.91 to 0.99)
Compared with living in Michigan, living in South Carolina, Washington, Los Angeles County, New York, or Texas lowered chances of any resistance testing.
Among people who had resistance testing, chances of getting tested within 1 month of linkage were lower in South Carolina and Washington (than in Michigan) and higher in New York. Men who inject drugs had a 13% lower chance of resistance testing at linkage than MSM (aPR 0.87, 95% CI 0.78 to 0.97).
The CDC researchers suggested that less resistance testing of men who inject drugs could reflect a lower chance that these men are considered candidates for antiretroviral therapy. They stressed that "increasing testing at linkage to care would help identify and address drug resistance early on."
1. Dasgupta S, Hall IH, Hernandez AL, et al. Receipt and timing of genotypic HIV drug resistance testing in the United States. Conference on Retroviruses and Opportunistic Infections (CROI), February 22-25, 2016, Boston. Abstract 500.