The effect of tenofovir on renal function and immunological response in HIV-positive patients in Lesotho

Abstract

INTRODUCTION: The renal effects of Tenofovir Disoproxil Fumarate (TDF) and antiretroviral treatment (ART) outcomes remain under-reported in African settings. The study sought to assess immunological outcomes and to compare renal function outcomes between patients exposed to TDF and unexposed patient group. METHODS: Phase 1 of the study was a retrospective case control analysis of serum creatinine data for 312 ART naïve adult patients exposed to TDF and 173 unexposed patients enrolled on ART between Dec 2006 and Jan 2011 at Roma Health Service Area in Lesotho. Sub-optimal renal function outcomes were serum creatinine clearance values <50 ml/min calculated using the Cockcroft-Gault equation. Phase 2 was based on re-sampling of the study population and analysis of CD4 counts of 516 adult naïve HIV-positive patients. Univariate logistic regression (p<0.1) and multivariate analyses (p<0.05) were performed using STATA® version 11 software. RESULTS: Overall, 153 (31.5%) patients had moderate baseline (30-60 ml/min) renal insufficiency. Renal function improved by +2 ml/min at 24 months. Almost 18% (n=312) of the patients on TDF were erroneously put on TDF. The use of TDF was a marginally significant factor (p=0.054) associated with CrCl<50 ml/min outcomes in univariate analysis but was insignificant (p=0.122) in multivariate analysis. Female gender (p=0.016), high blood pressure (p=0.009), ages over 60 (p=0.004), and underweight (p<0.001) were significantly associated with CrCl<50 ml/min outcomes. The proportion of patients who developed immunological failure in this study was low (6.8%, n=516). The mean CD4 count increased significantly after treatment (p<0.001). Baseline CD4 count below 50 cells/mm3 (p=0.049) and male gender (p=0.005) were significantly associated with sub-optimal immunological outcomes. CONCLUSIONS: TDF is a weak contributing factor associated with renal impairment outcomes compared to other variables such as hypertension, older age, underweight and female gender. More research on long term effects of TDF is recommended. Baseline renal function screening should be improved to minimise leakages of patients contraindicated of TDF. Although the patients’ immunological status generally improved, males and patients with low baseline CD4 counts should be monitored closely while on ART.