Age- and time-dependent increases in incident anti-glomerular basement membrane disease: a nationwide cohort study.

Background: Epidemiologic assessments of anti-glomerular basement membrane (GBM) disease have been challenging due to its rare occurrence. We examined changes in the incidence and outcomes from 1998 to 2018 using nationwide healthcare registries.

Methods: All patients with incident anti-GBM disease were identified using the International Classification of Diseases, 10th Revision code DM31.0A. Controls were matched 4:1 on birthyear and sex using exposure density sampling. Log link regression adjusted for time, age and sex was applied to model survival.

Results: We identified 97 patients with incident anti-GBM disease, corresponding to an incidence of 0.91 cases/million/year [standard deviation (SD) 0.6]. The incidence increased over time [1998-2004: 0.50 (SD 0.2), 2005-2011: 0.80 (SD 0.4), 2012-2018: 1.4 (SD 0.5);  = .02] and with age [0.76 (SD 0.4), 1.5 (SD 1.04) and 4.9 (SD 2.6) for patients <45, 45-75 and >75 years]. The median age was 56 years (interquartile range 46) and 51.6% were female. Dialysis was required in 58.4%, 61.9% and 62.9% of patients at day 30, 180 and 360, respectively. The 1-year kidney survival probability was 0.38 (SD 0.05) and exhibited time-dependent changes [1998-2004: 0.47 (SD 0.13), 2005-2011: 0.16 (SD 0.07), 2012-2018: 0.46 (SD 0.07);  = .035]. The 5-year mortality was 26.8% and mortality remained stable over time ( = .228). The risk of death was greater than that of the matched background population {absolute risk ratio [ARR] 5.27 [confidence interval (CI) 2.45-11.3],  < .001}, however, it was comparable to that of patients with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) requiring renal dialysis at presentation [ARR 0.82 (CI 0.48-1.41),  = .50].

Conclusion: The incidence of anti-GBM disease increased over time, possibly related to temporal demographic changes. Mortality remained high and was comparable with an age- and sex-matched cohort of dialysis-dependent AAV patients.