This resulted in many misclassified patients and common use of the code “00/ chronic renal failure; aetiology uncertain”. Secondly, the system was said to fail to capture important features of many conditions. It is however easy to use. A new coding system should be compatible with the existing ERA-EDTA PRD codes.
At the meeting of national registries at the Stockholm Congress, the working group will present a completely revised system. It is simple, comprehensive, expandable and will map to other coding systems while remaining easy to use.
For the first time the terms used have been defined. The coding group has avoided the temptation to write a textbook. The definitions will guide the nephrologists in the selection of the most appropriate diagnosis code when they have completed their investigations but should not be used to guide those investigations. A key feature of the system is the ability to state when the diagnosis has been confirmed by a renal biopsy while allowing an alternative code when patients present with classical clinical features in the absence of a biopsy. The system mentions only key diagnostic features, which allows the selection of the correct code. It does not mention other non-discriminating features even where these are very common (e.g. the presence of proteinuria in biopsy proven glomerulonephritis). National and regional registries will be asked for their comments and the working group will then discuss the codes with international registries, expert groups on specific diseases and coding organizations (e.g. Snomed). We hope that the QUEST groups and the ERA-EDTA Registry Committee will accept the new coding system by the end of 2008 and that thereafter it will be quickly and widely adopted.

Keith Simpson, Working Group Chair and Paul van Dijk, ERA-EDTA Registry medical informatician