25 February 2013
Taking the antiretroviral tenofovir was associated with loss of kidney function in a 10-year study of 1043 HIV-positive people in Canada. But most of the kidney function loss attributable to tenofovir occurred in the first year of treatment.
Tenofovir has become a widely prescribed antiretroviral; its use in multidrug pills is expanding; and it is seeing wider use in low- and middle-income countries. A link between tenofovir and declining kidney function has been appreciated since early development of this reverse transcriptase inhibitor, but the long-term magnitude and clinical impact of this loss remain uncertain.
To provide a long-term perspective on tenofovir use and kidney function, researchers in Montreal evaluated the impact of tenofovir use in 1043 HIV-positive people monitored for several years. The investigators defined kidney dysfunction as an estimated glomerular filtration rate (eGFR) below 90 mL/min/1.73 m(2). They estimated average loss of eGFR attributable to tenofovir over several years by linear regression analysis.
Median follow-up time was 7.9 years, median age at the start of follow-up was 39.3 years, and men made up 96% of the study group.
Compared with people who did not take tenofovir, those who did had a 63% higher risk of kidney dysfunction (hazard ratio 1.63, 95% confidence interval [CI] 1.26 to 2.10).
Cumulative eGFR loss directly attributable to tenofovir was −3.05 mL/min/1.73 m(2) after 1 year of treatment (P = 0 .017), −4.05 after 2 years (P = 0.000), −2.42 after 3 years (P = 0.023), and −3.09 after 4 years (P = 0.119). These rates indicated that most kidney function loss due to tenofovir occurs in the first year of therapy.
“In this cohort,” the researchers conclude, “tenofovir exposure was associated with reduced kidney function, but the loss in eGFR attributable to tenofovir is relatively mild in a long-term perspective.”
The authors note that the clinical impact of tenofovir-associated eGFR decline remains to be analyzed, “but it is highly plausible that tenofovir exposure, although associated with reduced kidney function, has no severe adverse effects over the long term for most HIV-positive patients.”
Source: Claudie Laprise, Jean-Guy Baril, Serge Dufresne, Helen Trottier. Association between tenofovir exposure and reduced kidney function in a cohort of HIV-positive patients: results from 10 years of follow-up. Clinical Infectious Diseases. 2013; 56: 567-575.
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