Epidemiology of glomerulonephritis in Northern Germany

Abstract

Background: Knowledge of the exact numbers of patients suffering from chronic diseases, possibly requiring costly continuous treatment, is mandatory for future health care plans. Despite some regional biopsy registries, no valid data about the epidemiology of glomerulonephritis in Germany exist, because all publications are hampered by their retrospective character and lack of completeness.

Methods: In a unique cooperation of out-patient nephrologists with a single major teaching hospital serving a population of approx. 600,000 in the capital of Schwerin and surrounding counties, all patients with abnormal urine findings and/or decreasing renal function of unknown cause were referred for renal biopsy between October 2002 and December 2008. The drop-out rate is assumed to be less than 5%. All biopsies were analysed according to international standards and traditional epidemiological and clinical parameters were collected for comparison with the micro-census of Mecklenburg-Lower Pomerania region of the year 2008. We present the first valid estimations of incidence and 7 year prevalence of glomerulonephritis in Germany.

Results: In 222 patients, 251 renal biopsies were performed. The annual biopsy rate was 64 per million population (pmp; range 46.2-87.2). The incidence and prevalence of glomerulonephritis over 7 years was 52 and 285 pmp, respectively. The most frequent glomerulonephritis subtype was mesangioproliferative glomerulonephritis (20.9 pmp) followed by focal and segmental glomerulosclerosis (FSGS, 11.2 pmp) of which 43% had an etiologic underlying condition. The incidences of minimal change nephropathy (MCN), membranous nephropathy and necrotising glomerulonephritis (NGN) were 3.2, 5.2 and 4.9 pmp. In one third of all cases, the glomerulonephritis was secondary (incidence of secondary glomerulonephritis 17.5 pmp). Lupus nephritis and ANCA-associated glomerulonephritis were found in 2.9 and 5.4 cases pmp.