Clinical progression of severely immunosuppressed HIV-infected patients depends on virological and immunological improvement irrespective of baseline status.

<bold>Objectives: </bold>The aim of this study was to analyse factors associated with progression to AIDS/death in severely immunosuppressed HIV-infected patients receiving ART.<bold>Methods: </bold>This study included naive patients from the PISCIS Cohort with CD4 <200 cells/mm(3) at enrolment and who initiated ART consisting of two nucleoside analogues plus either a PI or an NNRTI between 1998 and 2011. The PISCIS Cohort is a multicentre, observational study of HIV-infected individuals aged >18 years followed at 14 participating hospitals in Catalonia and the Balearic Islands (Spain). Clinical and laboratory parameters were assessed every 3-4 months during follow-up. Cox regression models were used to assess the effect of CD4 and viral load on the risk of progression to AIDS/death, adjusting for baseline variables and confounders.<bold>Results: </bold>2295 patients were included and, after 5 years, 69.9% reached CD4 ≥200 cells/mm(3), 64.4% had an undetectable viral load and 482 (21%) progressed to AIDS/death. The lowest rate of disease progression was found in patients who reached both immunological and viral responses during follow-up, regardless of their baseline situation (1.9% in baseline CD4 >100 cells/mm(3) and viral load <5 log copies/mL; 2.3% in baseline CD4 ≤100 cells/mm(3) and/or viral load >5 log copies/mL). Achieving a CD4 count ≥200 cells/mm(3) was the main predictor of decreased progression to AIDS/death. In those not reaching this CD4 threshold, virological response reduced disease progression by half.<bold>Conclusions: </bold>Even in the worse baseline scenario of CD4 ≤100 cells/mm(3) and high baseline viral loads, positive virological and immunological responses were associated with dramatic decreases in progression. [ABSTRACT FROM AUTHOR]