NATIONAL HARBOR, MD. – De novo dipstick proteinuria accurately predicted acute kidney injury among 328 critically ill septic patients, a retrospective chart study has shown.
With sepsis, inflammation results in increased capillary permeability to plasma proteins, manifesting in an increased excretion of albumin into the urine. Because the production of creatinine from the muscle is reduced in septic patients, relying on changes in serum creatinine could delay the diagnosis of this acute kidney injury (AKI), according to Dr. Javier Neyra.
"It is highly important to identify biomarkers that are sensitive, specific, and provide timely and early diagnosis of acute kidney injury before substantial damage has already been done. ... De novo dipstick proteinuria represents a simple, inexpensive biomarker in sepsis with predictive power for AKI," said Dr. Neyra of the Henry Ford Hospital, Detroit.
Charts from a total of 2,252 patients admitted to the intensive care unit for severe sepsis between January 2004 and July 2011 were analyzed retrospectively. Patients with a baseline serum creatinine level greater than 1.5 mg/dL, the presence of dipstick proteinuria within 3 months of the admission date, or common causes of false-positive dipstick tests such as urinary tract infection or gross hematuria were excluded. Of the remaining 470 patients, 328 had undergone dipstick testing on admission. Of those, 46% (152) had dipstick proteinuria.
Serum creatinine increased by at least 0.3 mg/dL in 210 (64%) patients within the first 72 hours of admission, signifying the first stage of acute kidney injury. In this group, new-onset dipstick proteinuria was found in 114 (54%) patients, for a positive predictive value of 75%. Dipstick proteinuria was found in 91 (55%) of 166 patients who met the Acute Kidney Injury Network criteria for AKI, for a positive predictive value of 60%.
Photo courtesy Dr. Javier Neyra
"De novo dipstick proteinuria represents a simple, inexpensive biomarker in sepsis with predictive power for acute kidney injury," said Dr. Javier Neyra of the Henry Ford Hospital, Detroit.
After adjustment for age, sex, race, comorbidities, hemodynamic status, and other variables, de novo dipstick proteinuria at the time of admission independently predicted AKI with an odds ratio of 2.3 (95% confidence interval, 1.4-3.8), Dr. Neyra reported in a poster at a meeting sponsored by the National Kidney Foundation.
In an interview, Dr. Neyra explained that such information identifies septic patients who would benefit from more careful monitoring of kidney function and hemodynamic stability. In addition, in those patients it would be important to avoid nephrotoxic agents such as aminoglycoside antibiotics and nonsteroidal anti-inflammatory agents, as well as exposure to contrast material unless it was absolutely necessary.
"The dipstick is a test that you already have in your hospital that you can utilize. It’s simple, inexpensive, and it’s already there," he said.
Dr. Neyra stated that he had no relevant financial disclosures.