Assessment of data quality in an international multi-centre randomised trial of coronary artery surgery

The analysis was based on the 2-page CRF completed at the 6 week follow-up. CRF pages were categorised into "clean" (no edit query) and "dirty" (any incomplete, inconsistent or illegible data). The timelines were assessed on the basis of the time interval from the visit and receipt of complete CRF. Data quality was defined as the number of data queries (in percent) and time delay (in days) between visit and receipt of correct data. Analyses were stratified according to the World Bank definitions into: "Developing" countries (Poland, Brazil and India) and "Developed" (Italy, UK, Austria and Australia).There were 18 centres in the "Developed" and 10 centres in the "Developing" countries. The rate of enrolment did not differ significantly by economic level ("Developing":4.1 persons/month, "Developed":3.7 persons/month). The time interval for the receipt of data was longer for "Developing" countries (median:37 days) compared to "Developed" ones (median:11 days) (p < 0.001). The median number of data queries was 23% in "Developed" countries compared to 19% in "Developing" ones (p = ns).In this study we showed that data quality was comparable between centres from "Developed" and "Developing" countries. Data was received in a less timely fashion from Developing countries and appropriate systems should be instigated to minimize any delays. Close attention should be paid to the training of centres and to the central management of data quality.ISRCTN46552265International multi-centre randomised trials are widely used to evaluate new investigational medicinal products or treatment strategies. It is essential that only accurate and verified data are collected in these trials in order that the results are reliable particularly as this may be used to inform guidance and recommendations for everyday clinical practise. However the collection of high quality data in these trials can be challenging because of several potential difficulties e.g. the inclusion of multiple centres with