The prevalence of chronic kidney disease in a Flemish primary care morbidity register

SIR—Based on earlier research [1, 2], we know that the estimated glomerular filtration rate (eGFR) decreases with age, starting in the third decade, even in healthy, normotensive adults. The components of this decrease in eGFR that are due to normal ageing and those that are due to non-ageing-related damage, caused by diabetes, hypertension, atherosclerosis or glomerulonephritis, remain uncertain. In this study, the data from a large Flemish general practice-based morbidity registry, called Intego, were used to obtain a clear view of the prevalence of chronic kidney disease (CKD) in primary care patients aged 50 and older as well as the prevalence of severe CKD (eGFR <30 ml/min) Data were obtained from Intego, a Flemish general practice-based morbidity registration network at the Department of General Practice at the Catholic University of Leuven. Ninety GPs, all using the medical software program Medidoc®, are currently collaborating on the Intego project. These GPs work in 55 practices distributed throughout Flanders, the northern part of Belgium. GPs whose data were accepted for inclusion in the database were selected on the basis of their excellent registration skills.