Kidney damage unlikely with TDF monotherapy in chronic HBV patients

By Shreeya Nanda, Senior medwireNews Reporter

In patients with chronic hepatitis B virus (HBV) infection, treatment with tenofovir disoproxil fumarate (TDF) does not significantly increase the risk of developing renal dysfunction compared with entecavir treatment, a US team reports.

The study included 103 TDF-treated chronic HBV patients with unimpaired or mildly impaired renal function, as defined by an estimated glomerular filtration rate (eGFR) of at least 80 mL/min per 1.73 m² or above 50 but lower than 80 mL/min per 1.73 m², respectively. Of these 15.5% were reclassified into a more severe category of renal impairment during treatment.

This proportion did not vary significantly from the 17.5% rate of reclassification observed in the 103 HBV patients – matched for age, gender and baseline eGFR classification – who were treated with entecavir, which the researchers explain is not known to be associated with renal dysfunction.

The TDF and entecavir groups also did not differ significantly in the proportion of patients who experienced a decrease in eGFR of 20% or more. Nor with regard to the incidence of reclassification to a more severe category, with an incidence density of 7.4 versus 11.5 cases per 100 person–years.

The relative risk of developing renal dysfunction as a result of exposure to TDF compared with nonexposure was 0.64, the team reports in the Journal of Clinical Gastroenterology.

And multivariate analysis showed that TDF exposure was not a significant factor predicting either reclassification to a more severe renal impairment category or a reduction in eGFR of at least 20%. By contrast, older age and pre-existing mild renal impairment were significantly associated with reclassification.

Researcher Mindie Nguyen, from Stanford University Medical Center in Palo Alto, California, and colleagues report that during the course of treatment four TDF-treated patients were moved from the mildly impaired to the moderately impaired (eGFR ≥30, <50 mL/min per 1.73 m²) category.

But they point out that as all four were older than 65 years of age with mildly impaired renal function at baseline, they cannot conclusively attribute the reclassification to TDF therapy.

The team concludes that although TDF is not a significant predictor of worsening renal function in this patient population, renal function should nonetheless be monitored closely during TDF treatment, especially in those who are older or have pre-existing renal dysfunction.

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