Validation of data and indicators in the Danish Cholecystectomy Database

In The Danish Cholecystectomy Database (DCD), quality indicators are derived from clinical data in combination with administrative data from the National Patient Registry. The indicators 'Length of postoperative stay <= 1 day and no readmission', 'Length of stay (LOS) > 3 days and/or readmission', 'Additional procedures within 30 days', 'Reconstructive bile duct surgery', 'Other surgery of the bile duct' and 'Death within 30 days' are all derived from administrative data. This study investigates the validity of the administrative data and evaluates the association between these indicators and postoperative complications. Data from 1360 medical records of patients undergoing cholecystectomy were compared with the relevant administrative data from the National Patient Registry. The medical records served as the 'gold standard'. The association between the individual indicators and the occurrence of a postoperative complication was assessed. Validation of administrative data against the gold standard was done by the calculation of per cent agreement (including kappa-values) sensitivity/specificity and predictive values. The association between indicators and complications was analysed with crude event rates and odds ratios. The validity of the administrative data was excellent (97.1-100% agreement, kappa = 0.73-1.00). All of the indicators except 'Other bile duct surgery' were significantly associated with postoperative complications. A subdivision of some indicators strengthened the associations. The DCD is a valid method for monitoring the quality of cholecystectomy in Denmark.