Renal dysfunction was more likely in patients who had taken tenofovir (Truvada, TDF) longer, were older, or also had diabetes or hypertension, according to a study presented at IDWeek 2014.
The study, a retrospective chart review presented by Jasmine Riviere Marcelin, M.D., investigated different methods for assessing kidney function in patients on tenofovir and found that serum creatinine was still the best way to monitor that population for potential kidney problems.
Study authors reviewed the charts of 177 HIV-positive adults on tenofovir-containing antiretroviral therapy who were treated at the Mayo Clinic in Rochester, Minn., between 2010 and 2013. There was no non-tenofovir control group because the majority of clinic patients' antiretroviral therapy regimens contained that drug. The study population did not include patients who had chronic kidney disease or proteinuria (excessive protein in urine) before starting tenofovir, nor those who also took other medications that could impair kidney function.
Study participants were between 33 and 57 years old (mean age 45), mostly male (81%), and mainly white. African Americans, who are at greater risk of kidney disease, constituted 19% of the study population. Participants had been taking tenofovir for a median of 3.3 years. Eleven people (9%) also had diabetes mellitus and 28 (24%) had hypertension. Other conditions included hyperlipidemia (39 participants, 33%), hepatitis C infection (16, 14%) and hepatitis B infection (14, 12%). Mean viral load at study start was 62 copies/mL, although 47 participants (40%) had a viral load above 1000 copies/mL.
Three renal function indicators were evaluated:
- eGFR, or estimated glomerular filtration rate
- urine protein-osmolality ratio (P:O ratio)
- predicted 24-hr proteinuria
An increased risk of abnormal eGFR was not associated with an abnormal P:O ratio or abnormal predicted 24-hour proteinuria (P = .334 and .213, respectively), leading study authors to conclude that, "serum creatinine remains the gold standard for monitoring of renal function while on tenofovir."
The age-adjusted risk of an abnormal P:O ratio was almost four times greater in patients who had taken tenofovir for more than 5 years compared to those who had taken it for less than 1 year (P = .024).
Other risk factors for abnormal kidney function included:
- Greater age: Those 54 years old had double the risk of abnormal eGFR readings (defined as < 60ml/min/1.73m2) compared to those 10 years younger (P = .048). Abnormal P:O ratios (P = .048) and abnormal 24-hr proteinuria (P = .01) were also more likely in older patients.
- Being diabetic: All 11 patients with that condition had abnormal P:O ratios.
- Having hypertension: Patients with hypertension were almost four times as likely to have an abnormal eGFR than those without that condition (P =.026).
Therefore, the study authors advise clinicians to, "use caution when prescribing TDF in older patients or patients with hypertension or diabetes."