September 6, 2012 — Patients who present with normal renal function and little blood or protein leakage into urine on diagnosis with immunoglobulin A (IgA) nephropathy have an excellent long-term prognosis, according to an article published online September 6 in the Journal of the American Society of Nephrology.
Eduardo Gutiérrez, MD, from the Department of Nephrology, Hospital 12 de Octubre, Madrid, Spain, and colleagues analyzed the records of 141 patients with minor abnormalities who had renal biopsies and were diagnosed with IgA nephropathy (IgAN). All patients were white, 90 (63.8%) were male, and the mean age was 23.7 years. No patients were treated with immunosuppressive medications.
Because common practice for nephrologists has been to order biopsies for patients who exhibit higher levels of proteinuria (protein leakage, 1 - 2 g/day), little information has been published on patients who exhibit proteinuria levels lower than 0.5 g/day, the researchers write. However, their study population consisted of patients at 8 Spanish hospitals that had adopted a policy of renal biopsy for patients with minor abnormalities. "We present the largest series of biopsy-proven IgAN presenting with hematuria and minimal or negative proteinuria so far collected," they write.
The researchers reviewed the patient records using the Oxford classification, a relatively new system for evaluating patients based on 6 pathological variables. They found that 96.7% of the patients maintained serum creatinine values less than a 50% increase after 10 years of follow-up, and that 91.9% maintained that value level after 15 years, and again after 20 years. Only 5 patients exhibited a greater than 50% increase from baseline serum creatinine, and only 1 patient, a 38-year-old woman, had a doubling of serum creatinine. No patients developed end-stage renal disease.
Using univariate analysis, the authors found that time-average proteinuria levels greater than 0.5 g/24 hours and the presence of segmental glomerusclerosis, one of the Oxford pathological variables, were significantly associated with a serum creatinine increase of more than 50%. In a multivariable model, they found that only the presence of segmental glomerusclerosis (hazard ratio, 6.86; 95% confidence interval, 1.08 - 43.55; P = .04) remained significant.
"[A] significant proportion of our patients (53 patients; 37.5%) showed a clinical remission of the disease defined by a disappearance of microhematuria and proteinuria ≤0.2 g/ 24 h together with normal renal function and normal [blood pressure]," the researchers write.
Their results are contrary to a few previous studies in China and Japan that showed IgAN to be a progressive disease with few patients making improvements. The authors of the current study speculate that the difference in outcomes could be related to genetics, as their entire study population was white. They also note that overweight and obesity had no effects on the outcomes.
"The favorable renal outcome of our patients is particularly remarkable when considering that they did not receive immunosuppressive treatments (including corticosteroids) or fish oil," the researchers write. Some patients were treated with medications to lower high blood pressure.
"We demonstrate that the long-term prognosis of this type of patient is excellent and that no special treatments other than those needed to lower blood pressure or treat increasing proteinuria are indicated," Dr. Gutiérrez said in a news release. "Our reassuring data are important because some previous studies had suggested that [IgAN] is a progressive disease even in this type of patient with benign presentation."
This study was funded by grants from Fondo de Investigaciones Sanitarias and the Asociación para la Investigación y Tratamiento de la Enfermedad Renal. The authors have disclosed no relevant financial relationships.
J Am Soc Nephrol. Published online September 6, 2012.
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Cite this: Nephropathy Patients Often Have Excellent Prognosis - Medscape - Sep 06, 2012.