Do current standards for determining lupus kidney flares need revision?
What is the topic?
Experts generally agree that excessive protein in the urine, known as “proteinuria,” is the most common symptom of a moderate or severe flare of lupus involving small blood vessels in the kidney. However, there is little agreement about how much of an increase in urinary protein indicates a flare. Establishing agreement on what constitutes a flare of lupus kidney disease could help identify the true status of the kidney in people with lupus.
What did the researchers hope to learn?
The researchers aimed to define normal fluctuations in levels of urinary protein in people with lupus kidney disease who are not experiencing a flare.
Who was studied?
The patients in this study were part of the Ohio SLE Study, which has a database of 106 typical people with active lupus. The study included data from 58 people having lupus kidney involvement. These patients provided 894 consecutive urine samples over the course of four to six months. All patients were receiving standard of care for lupus and their kidney involvement.
How was the study conducted?
The researchers determined levels of protein in the urine for all study participants by measuring, at 24-hour intervals, the ratio of proteins in the urine to a common urinary chemical called “creatinine.” Patients who experienced a kidney flare within the past four months were excluded from the study.
What did the researchers find?
Based on this analysis, patients experiencing the most common types of kidney flares would have delayed treatment for these flares. Conversely, for those with relatively high levels of proteinuria (in the absence of kidney flares), treatment may be initiated even before there is conclusive evidence that the degree of proteinuria has changed.
What were the limitations of the study?
Race is known to influence kidney flares identified by the methods used in this study. However, the researchers did not examine possible race-related differences in kidney flares in their analyses.
What do the results means for you?
The researchers suggest that current standards for lupus kidney flares may be set too low or too high. The results of this study may one day be used to help better guide treatment strategies for lupus kidney disease. However, this would first require a clinical trial to determine whether changing standards for identifying kidney flares would result in faster remission, a need for less drugs, and/or less long-term kidney disease.
An approach to validate criteria for proteinuric flare in systemic lupus erythematosus glomerulonephritis.
Ardoin S, Birmingham DJ, Hebert PL, Yu CY, Rovin BH, and Hebert LA. (2011).
Arthritis & Rheumatism 63: 2031-2037.