A Large Study Looks at Tenofovir and Kidney Health

Researchers in the United Kingdom recently conducted a large review of health records at two major HIV treating centres. Over a period of eight years their findings suggest that, for the most part, tenofovir (Viread) is a safe drug for the kidneys. However, tenofovir was associated with kidney damage among a subset of patients. The kidney damage cleared when the patients stopped taking the drug. Factors that placed tenofovir users at risk for kidney dysfunction are discussed later in this report.

Study Details

Over a period of eight years, data from 3,439 HIV positive people (28% female, 72% male) who sought care were collected at the study hospitals in London and Brighton. Below are the results from an analysis of that data.

Results

Among 843 people who took tenofovir during the study, 21 (or 2.5%) developed chronic kidney disease (CKD).

Although four tenofovir users died during the study period, this drug was not linked to their demise.

Risk Factors

Most people who take tenofovir do not develop any kidney problems, so the doctors were curious as to what factors these people might have had that made them susceptible to kidney disease. Among patients with pre-existing CKD (eGFR less than 60), tenofovir appeared to accelerate the decline of their kidneys. Among patients without pre-existing CKD, here is what the doctors found that likely played a role:

• being at least 50 years of age
• having mild kidney dysfunction (an eGFR greater than 60 but less than 90) before starting tenofovir
• having had prolonged HIV infection (for about 10 years)

This last point is interesting because it suggests the possibility that HIV itself may have played a role in affecting their kidney health prior to taking tenofovir.

The research team proposes that because the kidneys of these patients were not completely functional they could not rid the body of tenofovir, and so levels of this drug accumulated. In some cases, the doctors reduced the tenofovir dosage so that the eGFR could improve.

The study team noted that the results from this study "underscore" the need for monitoring kidney health, perhaps as soon as HIV positive people enter the medical health care system. Moreover, the researchers add that in people with certain features (such as diabetes, being 50 years or older, high blood pressure) perhaps frequent monitoring of eGFR and adjustment of tenofovir dosage may be necessary.

Reference

1. Campbell LJ, Ibrahim F, Fisher M, et al. Spectrum of chronic kidney disease in HIV-infected patients. HIV Medicine. 2009 Jul;10(6):329-36.

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