Lupus classification system too complicated

People with the autoimmune disease systemic lupus erythematosus (lupus) can experience a number of medical complications, including lupus nephritis, an inflammatory kidney disorder. Lupus nephritis affects approximately 3 out of every 10,000 people, and it can be serious and lead to kidney failure.

Classifying the severity of patients' lupus nephritis can help physicians choose appropriate therapies. The World Health Organization created a classification system that divided cases into six classes based on severity, and in 2003, the International Society of Nephrology and the Renal Pathology Society proposed some revisions. One of the most important changes subdivided class IV (when 50% or more of the kidney is diseased) into a segmental form and a global form depending on exactly how much of the kidney is affected.

This new classification of class IV lupus nephritis resulted from a study of 86 patients that suggested a difference in health outcomes, such as kidney failure, between those with segmental and global forms of the disease.

After the new classification system was published, various studies came to contradictory conclusions about differences in the health outcomes of patients in the two class IV groups. To provide some insight, Jo Berden, MD, PhD, Catharina Haring, MD (Radboud University Nijmegen Medical Center, in Nijmegen, The Netherlands), and their colleagues searched the medical literature and analyzed all of the studies and clinical trials that used the 2003 International Society of Nephrology and Renal Pathology Society classification of lupus nephritis in adult patients.

In the eight studies included in the final analysis, the incidence of kidney failure varied between 0% and 67%. The analysis did not support a significant difference in kidney outcomes between the segmental and global subclasses.

The results suggest the current classification system is too detailed. "This research is important because it could make the categorization of lupus nephritis easier and more comprehensive," said Dr. Berden.

More information: The article, entitled "Segmental and Global Subclasses of Class IV Lupus Nephritis Have Similar Renal Outcomes," will appear online on Thursday, October 27, 2011, doi:10.1681/ASN.2011060558

Provided by American Society of Nephrology