Epidemiology and temporal changes in the prognosis of rapidly progressive glomerulonephritis in Japan: a nationwide 1989–2015 survey

Background: Rapidly progressive glomerulonephritis (RPGN) can progress to end-stage kidney disease within a short period. This study is a continuation of the chronological nationwide survey conducted by the Japan-RPGN working group. Methods: We examined a total of 2793 RPGN cases registered during four periods (1989–1998, 1999–2001, 2002–2008, 2009–2011) plus 1386 cases in 2012–2015. As potential prognostic determinants, we investigated the onset period, the clinical severity (CS) grade [classified according to age, serum creatinine (sCr) and C-reactive protein levels, and presence/absence of lung lesions], and causative disease. Results: The cumulative overall RPGN patient survival at 24 months kept improving over the five periods (72.0%, 72.9%, 77.7%, 83.0%, 84.9%, p < 0.001 for trend). The cumulative renal survival also improved in the latest period (68.7%, 75.4%, 76.7%, 73.4%, 78.2%, p < 0.001 for trend). The CS grade was well stratified to predict both life and renal prognoses. Anti-glomerular basement membrane disease (aGBMD)-RPGN had a poorer renal prognosis than other diseases. In anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV-RPGN, accounting for > 70% of the overall RPGN), the prognostic results were similar to that for overall RPGN. There was a much better renal prognosis for the latest period under the condition of sCr < 3 mg/dL (the 24-month cumulative renal survival: 97.9%), but not for sCr ≥ 3 mg/dL (61.5%). Conclusions: In overall RPGN as well as AAV-RPGN, both life and renal prognoses tended to improve, but the favorable renal result was substantially limited to mild cases. There was no improvement of the renal prognosis in aGBMD-RPGN.