Treatment News

Compiled by Gus Cairns

Resistance tests still not being performed

Despite the BHIVA guidelines recommending that patients get tested for HIV drug resistance both when diagnosed and before starting HIV therapy for the first time, a study has found that pre-treatment resistance tests are still only being performed on 50% of patients.

The researchers from the UK CHIC Cohort Study found that one in ten of those given pre-treatment tests turned out to have HIV resistant to at least one drug and one in 22 patients had fewer than three HIV drugs they could respond to, leaving them open to treatment failure. For every drug patients were resistant to, their chances of achieving an undetectable viral load was cut by one third.
There were some signs of progress. The proportion of patients given a pre-treatment resistance test increased from13% in 1999-2001 to 37% in 2002-3 and 50% in 2004-6. Alongside this treatment success rates improved. The overall treatment success rate was 82% but patients were over twice as likely to fail therapy in 1999-2001 compared with 2004-6.

This reflects the refining of effective drug regimes. Patients taking the now old-fashioned unboosted protease inhibitor drugs were 60% less likely to achieve an undetectable viral load and patients taking triple-NRTI therapy such as Trizivir® (abacavir/3TC/AZT) were 50% less likely.

Patients were also more likely to fail therapy if they were younger, had a high pre-treatment viral load and had a higher than average CD4 count.

The UK CHIC researchers comment: “Selection of first-line HIV therapy should take into account the presence of transmitted drug resistance.”

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