title: The Berlin initiative study: the methodology of exploring kidney function in the elderly by combining a longitudinal and cross-sectional approach.
abstract: Epidemiologic data on incidence, prevalence and risk factors for chronic kidney disease (CKD) and its progression to kidney failure in people > or =70 years are scarce. This lack may have two reasons: First, the issue has only recently gained importance by the changing demographics characterized by an aging society. Secondly, a validated method for estimating kidney function in terms of glomerular filtration rate (GFR) in the elderly is still lacking. In this paper we describe the methodology of a combined longitudinal and cross-sectional approach of a population based study which will start in January 2010. The aims of the study are to identify prevalent and incident cases of CKD as well as co-morbidities and associated risk factors for progression of disease in this specific age-group. To assess prevalence, a new GFR estimation equation is to be developed. In a longitudinal approach a population based, age stratified sample of 2,000 subjects > or =70 years will be randomly drawn from a data base of a large health insurance company. Interview, physical examination, and preliminary estimation of GFR, based on serum creatinine will be performed. The entire cohort will be followed over the course of 2 years. In a cross-sectional approach a subsample of 600 subjects will be defined based on preliminary GFR values. Kidney function will be determined by measuring plasma clearance of an exogenous filtration marker (Iohexol). A new GFR-equation will be developed and validated using Iohexol clearance as gold standard to estimate GFR accurately and precisely. Data of 2,000 subjects will be used to estimate prevalence of CKD.
authors.affiliation: Division of Nephrology, Charité University Medicine, Campus Virchow, Augustenburger Platz 1, Berlin, Germany. elke.schaeffner@charite.de
authors.forename: Elke S
authors.initials: ES
authors.lastname: Schaeffner
authors.forename: Markus
authors.initials: M
authors.lastname: van der Giet
authors.forename: Jens
authors.initials: J
authors.lastname: Gaedeke
authors.forename: Markus
authors.initials: M
authors.lastname: Tölle
authors.forename: Natalie
authors.initials: N
authors.lastname: Ebert
authors.forename: Martin K
authors.initials: MK
authors.lastname: Kuhlmann
authors.forename: Peter
authors.initials: P
authors.lastname: Martus
mesh_terms: D000368:Aged; D001604:Berlin / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D005858:Germany; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D007676:Kidney Failure, Chronic / Q000453:epidemiology* / Q000209:etiology; D008137:Longitudinal Studies; D008297:Male; D011785:Quality Assurance, Health Care; D012307:Risk Factors