[Standardization criteria to ensure the uniformity of data collection by the Italian Registry of Dialysis and Transplantation].

The Italian Registry of Dialysis and Transplantation (RIDT) collects data concerning patients in renal replacement therapy (RRT) sent from Regional Registries. Until 2003, the data were sent in summary tables. From 2004, each region has been sending patient data as single non-summarized forms (i.e. one record for each patient). This paper summarizes the collection criteria and the ideal method to codify data ensuring that data sent to the RIDT are consistent. This standardization process is necessary to ensure the statistical analyzability of the data and their comparability with data from other registries. Moreover, the standardization process is the initial step in allowing the RIDT to obtain clinical data to transform the registry from an epidemiological registry to a clinical governance instrument.