Crescent subtype distribution and tubulointerstitial injury as predictors of renal function and renal replacement therapy in patients with crescent formation on renal biopsy: a single-centre retrospective cohort study

Aims: Crescent formation on renal biopsy, encompassing the histopathological spectrum of crescentic glomerulonephritis (CrGN), represents one of the most aggressive patterns of glomerular injury and is characterised by rapid decline in kidney function. The prognostic significance of different crescent subtypes and tubulointerstitial lesions remains incompletely understood. This study aimed to evaluate the association between crescent subtype distribution, tubulointerstitial pathology, and renal function parameters (eGFR, serum creatinine) and clinical outcomes (renal replacement therapy [RRT], mortality) in patients with crescent formation on renal biopsy. Methods: This retrospective observational study included patients with crescent formation on renal biopsy who underwent kidney biopsy at Bakırköy Dr. Sadi Konuk Training and Research Hospital. Clinical, laboratory, and histopathological data were obtained from hospital records. Crescent subtypes (cellular, fibrocellular, and fibrous), interstitial fibrosis, and tubular atrophy were recorded. Associations between histopathological findings and renal function parameters (eGFR and serum creatinine) and clinical outcomes (RRT and mortality) were analysed. Results: A total of 78 patients with complete histopathological and clinical data were included. Fibrocellular crescents demonstrated the strongest association with renal dysfunction, showing a significant negative correlation with eGFR and a positive correlation with serum creatinine. Fibrous crescents were significantly associated with lower eGFR and higher creatinine levels. Interstitial fibrosis and tubular atrophy were also associated with worse renal function at presentation. During follow-up, RRT was required in 12 patients (15.4%) and 5 patients (6.4%) died. Fibrous crescent percentage was significantly higher in patients requiring RRT. Conclusion: Crescent subtype distribution and tubulointerstitial injury are important determinants of renal function in patients with crescent formation on renal biopsy. In multivariable analysis, cellular crescent percentage and tubular atrophy were independently associated with lower eGFR, while cellular and fibrocellular crescents were independently associated with higher serum creatinine. Fibrous crescents were associated with the need for RRT in this exploratory analysis and warrant evaluation in larger prospective cohorts.