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.