Supersensitive Viral Load Assay in Predicting CD4-Guided Treatment Failure

Abstract

In HIV patients who discontinue highly active antiretroviral therapy (HAART), the degree of HIV RNA suppression at the time of treatment interruption may predict success of re-treatment after the interruption (STI). A case-control substudy of the Staccato trial in Thailand included CD4-guided STI subjects with HIV RNA > 50 copies /ml (virological failure cases, n=11) and HIV RNA < 50 copies/ml (controls, n=22) after 12-24 weeks of HAART re-treatment following a median of 2 STI cycles. Controls were matched for age, gender and pre-ART CD4 count. HIV RNA with 5 copies/ml detection limit was determined on pre-virological failure samples. HIV RNA increased in cases compared to controls with each successive STI cycle (p-trend across time-points 0.004). The last HIV RNA below 50 copies/ml was significantly higher among cases compared to controls (p=.004). Measuring HIV RNA below 50 copies/ml may be useful in predicting virological failure to STI.

Fig. (1)

The study design. HAART (highly active antiretroviral therapy), STI (structured treatment interruption), CT (Continuos Treatment) virological failure cases were defined as patients who had HIV RNA > 50 copies/ml after 24 weeks of HAART re-treatment following CD4-guided STI, non-virological failure controls were defined as patients with HIV RNA ≤ 50 copies/ml after 12-24 weeks of HAART retreatment who were matched with virological failure cases by gender, age and pre-treatment CD4 count.