Epidemiology of autosomal-dominant polycystic kidney disease: an in-depth clinical study for south-western Germany

As we emerge into the genomic medicine era, the epidemiology of diseases is taken for granted. Accurate prevalence figures, especially of rare diseases (RDs, 50/100 000), will become even more important for purposes of health care and societal planning. We noticed that the numbers of affected individuals in regionally established registries for mainly hereditary RDs do not align with published estimated and expected prevalence figures. We therefore hypothesized that such non-population-based means overestimate RDs and sought to address this by recalculating prevalence for an important common hereditary disease, autosomal-dominant polycystic kidney disease (ADPKD) whereby presumed-prevalence is 100250/100 000 The Else-Kroener-Fresenius-ADPKD-Study in south-west Germany with a population of 2 727 351 inhabitants was established with the cooperation of all nephrology centres. Furthermore, general practitioners, internists, urologists, human geneticists and neurosurgery centres were contacted with questionnaires for demographic, family and kidney function data. Germline-mutation screening of susceptibility genes PKD1 and PKD2 was offered. Official population data for 2010 were used for overall and kidney function-adjusted prevalence estimations. A total of 891 subjects, 658 index-cases and 233 relatives, aged 1089 (mean 52), were registered, with 90 response rate, 398 by nephrologists and 493 by non-nephrologists. Moleculargenetic analyses contributed to confirmation of the diagnosis in 57. The overall prevalence of ADPKD was 32.7/100 000 reaching a maximum of 57.3/100 000 in the 6th decade of life. Prevalence of ADPKD is overestimated by 2- to 5-fold and close to the limit of RDs which may be of broad clinical, logistic and policy implications.