Validation of the Danish Colorectal Cancer Group (DCCG.dk) database - on behalf of the Danish Colorectal Cancer Group.

AIM The aim of this study was to validate the clinical quality database of the Danish Colorectal Cancer Group. The validation is meant to focus on core data regarding staging of the disease, treatment provided, patient related factors and key complications. METHOD Database validation study assessing completeness of the database and the accuracy of data by re-entering of core variables into an online module in a blinded fashion and comparing re-entered data with the original database data. A sample of 5 % of patients from the years 2014 through 2017 was randomly selected. RESULTS The samples of 936 patients were identified, and data re-entered. Completeness of data retrieved was median 96%, 100% and 99% for preoperative, intraoperative and postoperative variables, respectively. Overall accuracy was median 95%. The least accurate variable was date of diagnosis (50% perfect agreement), with agreement rising to 96% when near-matches defined as correct date +/- 30 days were included. Intraoperative variables were of high quality, as were data on surgical complications including anastomotic leakage, where agreement was 97 %. CONCLUSION This was the first major validation of the Danish Colorectal Cancer Group's Database. Overall, the completeness and quality of data was high, but the validation process also identified weaknesses, which can be crucial for future users to acknowledge and consider. WHAT DOES THIS PAPER ADD TO THE LITERATURE?: Many studies as well as clinical and political decisions are based on data from clinical databases. It is therefore crucial that these are valid. In this study, a nationwide clinical quality database is validated, which contributes to the precision and impact of further studies based on data from the database.