Sep. 01, 2011

Comparison of Lupus Nephritis Classifications of Two International Organizations

Outcome of reclassification of World Health Organization (WHO) class III under International Society of Nephrology-Renal Pathology Society (ISN-RPS) classification: retrospective observational study. 
Hwang J, Kim HJ, Oh JM, Ahn JK, Lee YS, Lee J, Kim YG, Huh WS, Seo J, Koh EM, and Cha HS. (2011). Rheumatology International, epub ahead of print.

What is the topic?

Kidney involvement occurs in about 60% of people with lupus and is a major determinant of long-term disease outcome. Classes III and IV of lupus nephritis indicate the extent and pattern of damage to the kidney caused by inflammation due to lupus disease activity. This inflammation can affect parts of the kidney called “glomeruli,” which act as filters to remove waste products from the blood. In class III nephritis, there is damage to less than half of the total number of glomeruli, while in class IV, there is damage to more than half of the total number of glomeruli. 

The World Health Organization (WHO) published multiple versions of their classifications for lupus nephritis from 1975-2001, but they had several limitations. In 2004, the International Society of Nephrology-Renal Pathology Society (ISN-RPS) revised the WHO classifications for lupus nephritis. The major changes in the classifications included the addition of two sub-categories of lupus nephritis. Little is known about patient outcomes based on these revised classifications. 

What did the researchers hope to learn?

The researchers aimed to determine the effects of the ISN-RPS re-classifications for lupus nephritis on patient outcomes. 

Who was studied?

From 1995 to 2007, three pathologists at Samsung Medical Center in Seoul, Korea examined 43 kidney biopsy specimens from patients diagnosed with class III lupus nephritis based on the WHO criteria. 

How was the study conducted?

Forty-three kidney biopsy specimens were initially studied, but one patient could not be followed up. The final analysis thus included biopsies from 42 lupus nephritis patients. These kidney specimens were scored by microscopic analysis for severity of lupus nephritis. Clinical information and laboratory data were obtained from patients every 6-12 months. Clinical outcomes were assessed based on assessment of treatment regimens following kidney biopsy, changes in levels of protein in the urine, dose of cyclophosphamide or prednisone, and kidney response rate to treatment after one year. 

Based on several parameters, kidney response rate at the first year of follow-up was assigned to one of three groups: complete response, partial response, and no response. 

What did the researchers find?

All of the lupus nephritis patients were taking prednisone and most of them were women. The average time of follow-up did not differ depending on classification of lupus nephritis severity. Of the 43 patients with lupus nephritis, 12 (28%) of them were re-classified from WHO class III nephritis to ISN-RPS class IV nephritis, a more severe type of nephritis. 

Of the patients re-classified as ISN-RPS class IV, their activity index (which describes how inflamed the kidneys are) was greater than in those remaining in class III. Most of these did not achieve complete response after one year of treatment (75%) and 67% of them did not show a response to treatment. However, 53% of patients remaining in class III achieved complete response and only 23% were non-responders. 

Of the patients re-classified as class IV, 67% received immune-suppressing drugs whereas 60% of those remaining in class III did. 

About 22% of patients re-classified as class IV showed decreased levels of protein in the urine after one year of treatment, whereas 52% of those in class III did. 

About 25% of those in class IV experienced a clinical flare, whereas 40% of those in class III did. 

What were the limitations of the study?

This was a retrospective study, meaning that charts from previous patient assessments were studied. In such studies, some information may be missing from patient records. Also, a relatively small number of patients were studied here. Finally, other subclasses of lupus nephritis were not studied. 

What do the results means for you?

Overall, the patients re-classified as class IV (previously in class III) had increased activity indices, as well as reduced responses after one year of treatment, and worse kidney outcomes during follow-up. These results suggest that use of the ISN-RPS classification system is more useful than the WHO classifications in predicting kidney-related outcomes in people with lupus. This may provide better assistance in making decisions about treatments for lupus nephritis.

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