Towards a simplified renal histopathological prognostic score in glomerular nephropathies

An important role of native kidney biopsy evaluation is to predict renal prognosis. We aimed to develop a simplified chronicity score based solely on pathological features that are easily recognisable and can be found in all glomerular nephropathies (GN). In this retrospective study, observational cohort study we included 625 patients with GN diagnosis after native kidney biopsy in a tertiary unit between 1 January 2010 and 31 December 2015.

Presence of global glomerulosclerosis (GG), tubular atrophy (TA), interstitial fibrosis (IF) and fibrocellular/fibrous crescents (FC) in any grade was scored with one point; a final score was between 0 and 4 (i.e. 'absent' 0 score, 'moderate' 1-2 score, 'severe' 3-4 score). The primary endpoint was renal replacement therapy (RRT) initiation. Mean baseline estimated glomerular filtration rate (eGFR) was 55.9 ± 29.6 ml/min; during the follow-up (median = 27 months), 78 patients started RRT. The total mean renal survival time was 60.1 (58.0-62.1) months. GG (41%) was the most frequent lesion, followed by IF (25%), TA (18%) and FC (17%). Patients with absent (65.7; 63.6-67.8 months) chronicity had better renal survival than those with moderate (59.1; 56.1-62.2 months) or severe (42.7; 35.6-49.7 months) chronicity. The score was associated with renal survival [hazard ratio (HR) = 1.33; 1.08-1.64)] independently of the classical prognostic factors. Patients with moderate and severe chronicity had a two- and threefold increase in risk of RRT initiation.

Our score was correlated with renal survival independently of the traditional risk factors, and could improve outcome prediction in patients with GN by reducing the interobserver variability.