Increased incidence and improved prognosis of glomerulonephritis: a national 30-year study

While there are many cross-sectional studies of glomerulonephritis (GN) incidence, changes in incidence over time, particularly in the 21st century have received less attention. Similarly, little is known about temporal changes in GN prognosis. The presence in Denmark of comprehensive registries for renal biopsy results, end-stage renal disease (ESRD), comorbidity and mortality permit these questions to be addressed.

Data for all renal biopsies in Denmark between 1985 and 2014 were extracted from the Danish Renal Biopsy Registry and Patobank registries. The date of first dialysis or transplantation was extracted from the Danish Nephrology Registry for those patients developing ESRD. Dates of death and presence of chronic comorbid conditions at date of biopsy were extracted from the National Patient Registry. The incidence of GN, adjusted to the 2013 European standard population, was calculated. ESRD incidence and mortality were calculated, both in absolute terms and after correction for age, comorbidity and presence of renal tubulointerstitial fibrosis.

The incidence rose from 33.3 patients per million (ppm)/year in 1985-94 to 46.5 ppm in 2005-14. The increase could in part be related to changes in renal biopsy policy. Large increases in Anti-neutropil cytoplasmic antibody (ANCA) vasculitis (ANCAV) (3.1-7.7 ppm/year) and focal segmental glomerulosclerosis (FSGS) (1.5-5.7 ppm/year) incidence were noted. The biopsy-proven prevalence of GN in 2014 was 748 ppm of which 155 ppm were being treated with dialysis or transplantation. Adjusted ESRD incidence fell by 25% during the study period, mortality by 62% and combined ESRD/mortality by 46%. The fall in ESRD incidence was limited to minimal change GN, FSGS, membranous GN and lupus nephritis, while reductions in mortality, and the combination of ESRD and/or death, were seen for nearly all GN diagnoses.

This study suggests that the incidence of GN has generally increased between 1985 and 2014, but some of the increase may be related to changes in renal biopsy policy. Major increases in FSGS and ANCAV incidence have occurred. The prognosis of GN, both as regards ESRD and mortality, has improved.