Background: A simple method of measurement of chronic damage in renal biopsy specimens would be useful in clinical management, prognosis, comparisons between different centres and trials.
Methods: An interactive image analysis system was used to outline and measure areas of chronic damage in 247 renal biopsy specimens to give an index of chronic damage, expressed as a percentage of cortical cross-sectional area. Prognostic value was analysed by the Kaplan-Meier method to study time between biopsy and onset of permanent dialysis.
Results: There was no significant bias between measurements by the same observer or different observers. The index of chronic damage ranged from 0 to 90%. Increasing severity of chronic damage was associated with shortened renal survival. Each increase of 10% in the index increased the hazard ratio of risk of permanent dialysis by 1.5 times (95% confidence interval 1.4-1.7, P<0.001).
Conclusions: A simple measure of chronic damage was a powerful indicator of prognosis. This is likely to be clinically useful in routine practice and trials.