A urine dipstick test used to detect abnormal levels of protein in people with HIV and kidney disease was found to be largely inaccurate, according to new data from a study published in the February 1 issue of the Journal of Acquired Immune Deficiency (JAIDS) and reported by AIDSmap. The authors suggest that a slightly more detailed analysis of urine samples, called the protein-to-creatinine ratio (P/C), may yield more accurate results.
These new results are potentially significant, as the Infectious Disease Society of America, in its health care management guidelines for HIV-positive people living with chronic kidney disease, recommends regular dipstick testing to monitor for abnormal levels of protein in urine, called proteinuria. Proteinuria can be a sign of serious kidney dysfunction, and early detection and treatment are recommended.
Mark Siedner, MD, MPH, from the Johns Hopkins University School of Medicine in Baltimore, and his colleagues compared the results of two competing tests, the urine dipstick and a P/C ratio test, in 166 people with HIV receiving care at the university’s kidney disease clinic.
Siedner’s team compared samples only if a person’s dipstick test and P/C ratio were taken no more than 48 hours apart, in order to ensure that the comparison was valid. They also placed emphasis on test results in people with mild proteinuria—a result of ≥ +1 for the dipstick test or a range of 0.30 to 0.99 for the P/C ratio—as early detection of proteinuria is a central goal of dipstick testing.
The team found that the dipstick test gave false results a significant percent of the time. A false-positive result—where the dipstick test read ≥ +1, but the P/C ratio was less than 0.30—occurred in 12.5 percent of participants. More disturbing, a false-negative result—where the dipstick test showed no abnormal protein, but the P/C ratio was greater than 0.30—occurred in 21 percent of the participants.
Given that several other studies have found the dipstick test to give inaccurate results, the authors assert that guidelines recommending its routine use be revisited and that more research to determine the most accurate measure of mild proteinuria should be conducted.
