Powerful morphometric indicator of prognosis in lupus nephritis

Background: Changes in renal biopsies in lupus nephritis have been analysed in many ways, but few have had prognostic value. Aim: To see whether a morphometric measure of chronic renal damage that was a prognostic indicator in other conditions had similar value in lupus nephritis. Design: Retrospective analysis of biopsies and study of outcome. Methods: On sections of 260 biopsies from 182 consecutive patients with systemic lupus erythematosus, an image analysis system measured chronic damage as a proportion of cortical area, to give the index of chronic damage. This was related to survival (until death or onset of dialysis). Patients were followed for up to 20 years. Results: The index of chronic damage ranged from 0 to 93%. Twenty-three patients (13%) died before dialysis, many from infection or myocardial infarction, and 40 (22%) went onto permanent dialysis. There were strong correlations between the index and time until death or dialysis (log rank test: chi(2) = 51.08, three degrees of freedom [df], p<0:001) and time to dialysis (log rank test: chi(2) = 72.88, 3df, p<0.001), but there was no correlation with time until death before dialysis (log rank test: chi(2) =0.36, 3df, p>0.9). WHO class of nephritis had no major relation to outcome after the index was taken into account and after appropriate treatment of the different classes. Discussion: The index was a strong indicator of risk of progression to renal failure in lupus nephritis, but not of risk of death before dialysis. This will be useful in clinical management and treatment trials.