(HealthDay)—Proteinuria levels at 12 months are the best predictor of long-term renal outcome in patients with lupus nephritis, according to a study published in the May issue of Arthritis & Rheumatology.

Maria Dall'Era, M.D., from the University of California in San Francisco, and colleagues analyzed data from the Euro-Lupus Nephritis Trial to evaluate the performance of proteinuria, (Cr), and urinary red blood cells (RBCs) as predictors of good long-term renal outcome (defined as a serum Cr value ≤1.0 mg/dL) in patients with . Seventy-six were followed for a minimum of seven years.

The researchers found that a proteinuria value of <0.8 gm/day at 12 months after randomization was the single best predictor of good long-term renal function (sensitivity of 81 percent and specificity of 78 percent). The performance of the outcome measure was not improved with the addition of serum Cr to proteinuria. Sensitivity dropped to 47 percent with the addition of urinary RBCs.

The authors suggest "that urinary RBCs should not be included as a component of clinical trial response criteria in lupus nephritis."

One author disclosed financial ties to the pharmaceutical industry.