Information derived from hospital coded data is inaccurate: the Birmingham Women's Hospital experience.

We tested the accuracy of coded hospital information on the Patient Administration System (PAS), a major component of the Hospital Information Support System (HISS). This is the main electronic database used for healthcare research, audit, and planning in National Health Service hospitals in the UK. The accuracy of electronic records of diagnoses, interventions and diagnosis-intervention pairs was low. (Kappa agreement statistics [k] were 0.39, 0.30, and 0.21 respectively). A major source of error arose because the databases of maternities and surgical operations were not seamlessly linked to the PAS.