Nephrotoxicity associated with antiretroviral therapy in HIV-infected patients

HIV associated kidney diseases: Clarifying concordance between renal failure in HIV infection and histopathologic manifestations at kidney biopsy

Patients with HIV infection have a wide spectrum of renal diseases. Some are known to be the direct effect of the viral infection while others are renal diseases that also occur in uninfected populations. HIV associated nephropathy (HIVAN) is considered to be a subtype of primary focal and segmental glomerulosclerosis that is distinct in HIV infected patients. It is more frequent in the African-American population and associated with mutations of the apolipoprotein L1 (APOL1) gene. HIV associated immune complex kidney disease (HIVICD) encompasses a spectrum of HIV associated renal diseases characterized by the presence of immune complex deposition within glomeruli. Thrombotic microangiopathy (TMA) is a complication of HIV infection that presents with hemolytic anemia, thrombocytopenia, and renal failure. TMA in HIV patients is associated with very high mortality. Lastly, the multitude of antiretroviral drugs used for treatment of HIV infections can result in nephrotoxicity. Although a kidney biopsy may not be the first line study for renal disease, knowledge of the different histopathologic features of HIV-associated and unassociated diseases is of paramount importance in the treatment and subsequent outcome of renal function in HIV infected patients. In this review we will describe the histopathologic features and discuss the pathophysiology of the entities previously named.

Prevalence and significance of proximal renal tubular abnormalities in HIV-infected patients receiving tenofovir

OBJECTIVES

Patients receiving tenofovir, disoproxil, fumarate (TDF) had an increased prevalence of proximal renal tubular dysfunction (PRTD), but contributing factors and its clinical significance remain controversial.

DESIGN AND METHODS

Cross-sectional evaluation of different urinary parameters (proteinuria, albuminuria, phosphaturia, uricosuria, glycosuria) in 200 HIV-infected patients receiving TDF, 26 following TDF discontinuation, and 22 never treated with TDF, included in a prospective cohort study. PRTD was defined as two or more tubular abnormalities.

RESULTS

After a median of 65 months (interquartile range, 42.7-84.7), at least one tubular alteration was found in 72% of patients, mostly proteinuria (42, 50, and 14% in current, previous and never TDF use; P=0.02) and phosphaturia (46, 42, and 14%; respectively, P < 0.01). PRTD was found in 63 patients (32%) receiving TDF, ranging from 14 to 46% according to concomitant hepatitis C virus coinfection, diabetes mellitus or hypertension arterial, in contrast with six (23%) following TDF discontinuation, and zero cases in no TDF-treated patients. The use of TDF [odds ratio (OR) 13.2; 95% confidence interval (CI) 1.4-22.7; P = 0.01], cumulative time on combination antiretroviral therapy (OR 1.011; 95% CI 1.07-1.019 per month; P = 0.01), and baseline estimated glomerular filtration rate (eGFR, OR 0.97; 95% CI 0.94-0.99 per ml/min per 1.73 m higher; P = 0.04) were associated with PRTD. The number of tubular abnormalities was linearly associated with eGFR decline since TDF initiation (β-coefficient -0.15, P = 0.02), together with age (-0.18; P = 0.01), baseline eGFR (0.49, P = 0.01), diabetes mellitus (-0.19, P = 0.02), and time on TDF (-0.23; P = 0.01).

CONCLUSION

The use of TDF leads to an increased rate of tubular dysfunction, and modulated by age, baseline eGFR, and classical factors, is associated with kidney function decline.

Antiretroviral therapy, immune suppression and renal impairment in HIV-positive persons

PURPOSE OF REVIEW

The purpose of this article is to review recent literature on antiretroviral treatment (ART) and immune suppression as risk factors for renal impairment in HIV-positive persons, and to discuss pending research questions within this field.

RECENT FINDINGS

Several individual antiretroviral agents (ARVs) including tenofovir and several protease inhibitors have, in diverse study settings, been associated with renal impairment. Traditional renal risk factors are common among those experiencing adverse renal impairment to ARVs, but do not fully explain why only some develop these effects. Discontinuation of nephrotoxic ARVs is common with declining renal function, but has unknown long-term consequences. Immune suppression is a strong independent risk factor for renal impairment, and ongoing investigations will clarify whether initiating ARVs with nephrotoxic properties at higher CD4 cell counts will have net beneficial effects on renal function.

SUMMARY

With improvements in survival, multiple risk factors have emerged for renal impairment in HIV-positive persons. Although certain ARVs may cause moderate renal impairment, effects on more severe renal impairment remain unresolved. Regular renal function monitoring allow for switching away from nephrotoxic ARVs in case of decreasing function. If such actions prove beneficial higher prevalence of ARV-associated severe renal impairment may emerge in populations without access to regular monitoring.

Renal dysfunction among HIV-infected patients starting antiretroviral therapy

OBJECTIVE

HIV-related renal dysfunction is associated with high mortality. Data on the prevalence of renal dysfunction among HIV-infected outpatients starting antiretroviral therapy (ART) in sub-Saharan Africa are limited. Recent recommendations to include the nephrotoxic drug tenofovir in first-line ART regimens make clarification of this issue urgent.

METHODS

We screened for renal dysfunction by measuring serum creatinine, proteinuria, and microalbuminuria in HIV-positive outpatients initiating ART in Mwanza, Tanzania. We excluded patients with pre-existing renal disease, hypertension, diabetes, or hepatitis C virus co-infection. Estimated glomerular filtration rates (eGFRs) were calculated by Cockroft-Gault and Modification of Diet in Renal Disease equations.

RESULTS

Only 129 (36%) of 355 enrolled patients had normal eGFRs (grade 0 or 1) above 90 ml/min per 1.73 m. Grade 2 renal dysfunction (eGFR between 60 and 89 ml/min per 1.73 m) was present in 137 patients (38.6%), and 87 patients (25%) had grade 3 dysfunction (eGFR between 30 and 59 ml/min per 1.73 m). Microalbuminuria and proteinuria were detected in 72 and 36% of patients, respectively. Factors predictive of renal dysfunction in multivariate analysis included female sex [odds ratio (OR) 3.0, 95% confidence interval (1.8-5.1), P < 0.0001], BMI less than 18.5 [OR 2.3 (1.3-4.1), P = 0.004], CD4 T-cell count below 200 cells/μl [OR 2.3 (1.1-4.8), P = 0.04], and WHO clinical stage II or above [OR 1.6 (1.2-2.3), P = 0.001].

CONCLUSION

Renal dysfunction was highly prevalent in this population of HIV-positive outpatients initiating first ART in Tanzania. This highlights the critical and underappreciated need to monitor renal function in HIV-positive patients in sub-Saharan Africa, particularly given the increasing use of tenofovir in first-line ART.

The nephrotoxic effects of HAART

With significant reductions in mortality and risk of progression to AIDS in the era of highly active antiretroviral therapy (HAART), complications of long-standing HIV infection and treatment have become increasingly important. Such complications include the nephrotoxic effects of HAART, which are the subject of this Review. The most common nephrotoxic effects associated with HAART include crystal-induced obstruction secondary to use of protease inhibitors (mainly indinavir and atazanavir), and proximal tubule damage related to the nucleotide analog reverse transcriptase inhibitor tenofovir. Acute kidney injury (AKI) can occur following tenofovir-induced tubule dysfunction or as a result of severe mitochondrial dysfunction and lactic acidosis induced by nucleoside reverse transcriptase inhibitors. The potential insidious long-term renal toxicity of antiretroviral treatment is probably underappreciated in patients with HIV: a proportion of patients with treatment-related AKI did not recover their baseline renal function at 2-year follow-up, suggesting the possibility of permanent renal damage. Finally, nonspecific metabolic complications might increase the risk of vascular chronic kidney disease in patients on HAART. However, given the benefits of HAART, fear of nephrotoxic effects is never a valid reason to withhold antiretroviral therapy. Identification of patients with pre-existing chronic kidney disease, who are at increased risk of renal damage, enables appropriate dose modification, close monitoring, and avoidance or cautious use of potentially nephrotoxic medications.