DIFFERENTIATION STAGE, ACTIVATION AND APOPTOSIS OF T CELLS IN A COHORT OF LONG-TERM NON-PROGRESSORS WITH DIVERGENT CD4 OUTCOME

OBJECTIVES: With the addition of tenofovir to antiretroviral therapy renal safety became a concern. Estimation of the glomerular filtration rate (GFR) based on serum creatinine and formula calculations are easy to perform, but less sensitive and may be affected by weight changes (MDRD formula). A recent marker of GFR is serum cystatin C which is not affected by weight changes and may be more sensitive than formula calculations based on serum creatinine. METHODS: Caucasian HIV-positive patients starting antiretroviral therapy (n=99) were followed prospectively and GFR was estimated using MDRD and Cockcroft-Gault (CG) formula. Cystatin C was measured in serum. GFR normal >90 mL/min, mild reduction 60-90 mL/min, moderate 30-60 ml/ min, severe 15-30 mL/min, renal failure <15 ml/min. RESULTS: Percentage of patients with mild/moderate impairment at baseline/24 weeks of therapy was 22%/25% with MDRD, 19%/23% with CG and 83%/53% with cystatin C. No severe impairment or renal failure was observed. The median GFR / median change in mL/min after 24 weeks on therapy was 103/-4 with MDRD, 117/-4 with CG and 77/+12 with cystatin C (all changes p<0.01). Patients on tenofovir (n=66) showed a slight reduction in GFR over 24 weeks of -8 mL/min based on MDRD or CG whereas an 11 mL/min increase in GFR was observed with cystatin C (all changes p<0.001). No change of GFR was observed for patients on non-TDF regimen (n=33) based on MDRD/CG and a non significant increase with cystatin of 12 mL/min. CONCLUSIONS: Marked differences were observed between calculations of GFR based on serum creatinine or serum cystatin C. With cystatin significantly more patients had mild impairment of renal function. The effect of antiretrovirals on GFR was subclinical, but differed in direction between