A new study finds “substantial” variation in oral diuretic use, dosing, and monitoring in real-world hemodialysis practice in the US.

According to 2017 data from the US Renal Data System (USRDS), only 22,296 of 176,448 patients (13%) on maintenance hemodialysis were taking a diuretic, Jennifer E. Flythe, MD, MPH, and Magdalene M. Assimon, PharmD, PhD, of the University of North Carolina Kidney Center at Chapel Hill, reported in Kidney Medicine. In contrast, 45% of European and 48% of Japanese patients continue diuretics after hemodialysis initiation.

Diuretic users were more likely than nonusers to be older and White. They had a higher prevalence of heart failure and hypertension. They also tended to have a shorter dialysis vintage.

The majority of diuretic users (90%) were taking a loop diuretic, whereas 8% were taking a thiazide/thiazide-like diuretic, 6% were taking a potassium-sparing diuretic, and less than 1% were taking a carbonic anhydrase inhibitor, according to the investigators.

Furosemide was the most commonly used loop diuretic (83%). Fewer used bumetanide (9%), torsemide (7%), and ethacrynic acid (less than 1%). Furosemide-equivalent dosing ranged widely from 20mg or less (8%) to more than 320mg (1%) daily. Dosing did not differ among groups receiving hemodialysis for less than 1 year, 1 to 2.9 years, or 3 years or more.

Only 28% of loop diuretic users were taking doses exceeding 80mg furosemide-equivalents per day, Drs Flyth and Assimon reported. Thiazide/thiazide-like diuretics and aldosterone antagonists were frequently taken without concomitant loop diuretic therapy.

In secondary analyses, the investigators compared 24-hour urine measurement results from 6659 (11%) diuretic users and 51,420 (89%) non-users. Just 3% of diuretic users and 2% of non-users underwent a 24-hour urine volume measurement in the prior 180 days, they reported.

Diuretic users vs nonusers had a larger median urine volume: 700 vs 200mL per 24 hours, respectively. Urine volumes did not correspond to dosing, however. Among 176 loop diuretic users, median urine volume was 700mL per 24 hours whether the furosemide-equivalent dose per day was 80mg or less or more than 80mg.

“Our analysis reveals substantial variation in diuretic use, dosing, and monitoring in US hemodialysis practice,” Dr Flythe and Dr Assimon wrote. “We found that diuretic dosing was particularly variable, with the majority of patients prescribed loop diuretics at furosemide-equivalent doses lower than what is recommended in non-dialysis-dependent chronic kidney disease.”

Variations in diuretic prescribing likely reflect clinician uncertainty over the risks vs benefits of diuretic therapy in patients receiving hemodialysis, Dr Flythe and Dr Assimon observed. Higher loop diuretic dosing is necessary for efficacy, but kidney function decline can prolong drug elimination. When a loop diuretic dose is too high, tinnitus, ototoxicity, and other side effects may occur. Loop diuretics also compete for protein-binding sites, increasing the risk of drug-drug interactions.

According to findings from a 2019 study published in the Clinical Journal of the American Society, staying on loop diuretics during the dialysis transition may lead to less interdialytic weight gain, intradialytic hypotension, and hospitalization. The study could not account for residual kidney function, however.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

Reference

Flythe JE, Assimon MM. Diuretic use among hemodialysis patients in the United States. Kidney Med. Published online July 21, 2022. doi:10.1016/j.xkme.2022.100520

This article originally appeared on Renal and Urology News