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Session 80 Poster Abstracts
Antiretroviral Therapy: Predictors of Response and Virologic Failure
Monday, 1:30 - 3:30 pm
Poster Hall


557
Low Baseline CD4 T-cell Count and Higher Age Predict Poor CD4 T-cell Recovery in Treated HIV-1 Infected Individuals Suppressing HIV-1 RNA to Levels <1000 copies/mL for 5 Years
G Kaufmann*1, H Furrer2, L Perrin3, C Ungsedhapand1, M Opravil4, M Egger5, M Cavassini6, P Vernazza7, E Bernasconi8, M Rickenbach9, B Hirschel10, M Battegay1, and the Swiss HIV Cohort Study
1Univ. Hosp. Basel, Switzerland; 2Univ. Hosp. Berne, Switzerland; 3Lab. of Virology, Univ. Hosp. Geneva, Switzerland; 4Univ. Hosp. Zurich, Switzerland; 5Univ. of Berne, Switzerland; 6CHUV, Switzerland; 7Cantonal Hosp. St.Gallen, Switzerland; 8Regional Hosp., Lugano, Switzerland; 9Data Ctr. of the SHCS, CHUV, Switzerland; and 10Univ. Hosp. Geneva, Switzerland

Background: Antiretroviral therapy (ART) for HIV-1 infection results in variable recovery of CD4 T-lymphocytes. Few studies have explored the characteristics and predictors of poor CD4 T-cell responses to long-term ART.

Methods: Longitudinal CD4 T-cell count was analyzed in 326 participants of the Swiss HIV Cohort Study (75% male, mean age 37.5y) who continuously suppressed plasma HIV-1 RNA to levels <1000 copies/mL during a median observation period of 5.7 years (range: 5.0-6.4 years). Poor CD4 responders were defined as individuals who did not reach CD4 T-cell counts >500 cells/mL at 5 years. Potential predictors of poor CD4 T-cell responses including age, gender, transmission group, duration of HIV infection, CDC stage, HCV and HBV co-infection, baseline CD4 and CD8 T-cell counts, and baseline viral load were evaluated using logistic regression. Patterns of CD4 T-cell recovery were analyzed by a non-linear regression model.

Results: Median CD4 T-cell count increased from 211 to 609 cells/mL at 5 years. Median annual CD4 T-cell rises declined over time and were in the first to fifth year 168 cells/mL, 83 cells/mL, 62 cells/mL, 29 cells/mL and 30 cells/mL, respectively. At 5 years, 98.2% reached >200, 84.0% >350 and 62.5% >500 CD4 T-cells/mL. Of 37.5% with poor CD4 T-cell responses, CD4 T-cell count either reached a plateau (no further increase in CD4 T-cell count; 41%) or continued to increase slowly (59%). Risk factors of failing to reach CD4 T-cell counts >500 cells/mL at 5 years included higher age (odds ratio (OR) 3.04/10 years increase; p = 0.001) and lower baseline CD4 T-cell count (OR: 2.6/100 cells increase; p <0.001). The same factors increased the risk of reaching a CD4 T-cell plateau <500 cells/mL (age: odds ratio 2.6/10 years increase; p = 0.007; lower baseline CD4 T-cell count: odds ratio 0.54/100 cells increase; p = 0.010). CD4 T-cell increases did not depend on baseline CD4 T-lymphocyte levels.

Conclusions: At 5 years, 37.5% of patients with well-suppressed plasma HIV-1 RNA levels met the criteria of poor CD4 T-cell responders. These individuals were characterized by higher age and lower baseline CD4 T-cell count. However, the percentage of poor responders who reached a CD4 T-cell plateau below 500 cells/mL was small.

Keywords: long-term immunologic recovery; CD4 T-lymphocytes; CD8 T-lymphocytes