Accurate Diagnosis of Lupus May Be Close

Researchers have found that comparing the ratios of erythrocyte-C4d and complement receptor 1 (CR1) proteins in blood samples allowed them to diagnose patients suffering from systemic lupus erythematosus (SLE) with a high level of reproducibility.

Investigators at the University of Pittsburgh (PA, USA) conducted a cross-sectional study of 100 patients with SLE, 133 patients with other diseases, and 84 healthy controls. Levels of C4d and CR1 on erythrocytes were determined by indirect immunofluorescence and by flow cytometry.

Results published in the November 2004 issue of Arthritis & Rheumatism showed that patients with SLE had higher levels of C4d and lower levels of CR1 than did patients with other diseases or healthy controls. The test was 81% sensitive and 91% specific for SLE versus healthy controls, and 72% sensitive and 79% specific for SLE versus other diseases, with an overall negative predictive value of 92%.

"Lupus is the prototypical autoimmune disease and arguably the greatest diagnostic challenge among rheumatologic diseases,” explained senior author Dr. Joseph Ahearn, associate professor of medicine at the University of Pittsburgh School of Medicine. "The spectrum of disease among patients with SLE is broad and ranges from subtle or vague symptoms to life-threatening multi-organ failure, and the manifestations of lupus often mimic those of other diseases, making it difficult to diagnose. Today we are one step closer to providing patients with an immediate and accurate diagnosis, one step closer to providing physicians with the ability to offer better treatment options and one step closer to providing incentives to lower the cost of health care for patients suffering from lupus.”




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