Quality control of validity of data collected in clinical trials. EORTC Study Group on Data Management (SGDM).

In a study initiated by the EORTC Study Group on Data Management, 15 site visits to main participating centers in ongoing cancer clinical trials have been carried out over a 1 year period. The aim was to evaluate the quality level of EORTC clinical trial data, to find out the order of magnitude of possible problems encountered and to test a technique to objectively assess the quality of data. The process of data collection and the quality of data transfer from hospital charts to EORTC case report forms (CRF) were checked. The data quality was scored and the causes of incorrectness were evaluated. Percentages of correct data ranged from 78% up to 98%; 11/15 centers had greater than 90% correct data. The median rate of error encountered in key data was 2.8% (range 0.5-7%). The main source of error was incorrect transfer of the information recorded in the patient chart to the CRF. Equally good overall results have been observed in the centers where data managers fill in the forms (DM) and those centers without an administrative trial structure (PH). The mean percentage of correct data for both types of centers is 91.4%. The wider range in percentage for incorrect data (DM mean value 3.0%, range 0.5-7%; PH mean value 2.3%, range 1.4-3.1) suggests the important impact of the knowledge and experience of the people involved in data management. The data quality evaluation was hampered by the impossibility of checking part of the data present on the CRF, 0.4-14.5%. Besides knowledge and experience, the main aspects influencing good data quality appeared to be the efficacy of the internal organization and good local data monitoring. The importance of the design of CRFs was also highlighted. As this study was run for on-going protocols, the site visiting team had the opportunity to point out and report to the trial coordinator all shortcomings and controversial points that could thus be corrected during the course of the trial.