Temporal changes of the life and renal prognoses of patients with rapidly progressive glomerulonephritis in Japan, 1989-2019.

Background: This study is a continuation of the Japan Rapidly Progressive GlomeruloNephritis (RPGN) Working Group's chronological nationwide survey.

Methods: We analyzed 1,660 RPGN cases from 2016-2019 and compared them to 4,179 cases from five earlier periods (1989-1998, 1999-2001, 2002-2008, 2009-2011, 2012-2015). Data on causative diseases, clinical severity, 24-month life and renal survival, and treatment details were collected and compared.

Results: The most recent cohort showed an older median age at onset (median age 74 years), with improved serum creatinine levels (median 2.5 mg/dL). Cumulative survival at 24 months remained stable (periods 1989-1998, 1999-2001, 2002-2008, 2009-2011, 2012-2015, 2016-2019 were each 72.0%, 72.9%, 77.7%, 83.0%, 84.9%, 83.5%, p < 0.01), while renal survival showed a favorable trend in the most recent periods (there were each 68.7%, 75.4%, 76.7%, 73.4%, 78.2%, 78.4%, p < 0.01). Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV)-RPGN had similar outcomes to the overall cohort. Increased rituximab use was observed, with no significant differences in life and renal prognosis between rituximab (RIX) and cyclophosphamide (CY). In severe renal impairment (Cre ≥ 6), renal prognosis was better in the CY or RIX use group than in the non-use group (p = 0.035, 0.025). Anti-glomerular basement membrane disease had a poorer renal prognosis compared to other causes.

Conclusions: Despite an increasingly older age of onset, both life and renal prognoses for new-onset AAV-RPGN from 2016 to 2019 remain comparable to the best in previous surveys, due to the impact of constant improvements in early diagnosis and changes in treatment.