Modern health care involves the routine collection of administrative data primarily for management and accounting purposes. Such databases include some clinical data (such as type of surgery, diagnosis, length of stay) that might be useful in monitoring quality of care.1 2 3 4 In this week's BMJ, Aylin and colleagues5 have used hospital episode statistics (HES) data, which are routinely collected by the UK National Health Service, to develop statistical models for predicting hospital mortality adjusted for case mix in three well defined clinical areas—cardiac surgery, aortic aneurysm repair, and colorectal cancer.

Previous comparisons of administrative databases and clinical databases or medical notes (chart review) have found administrative databases to be lacking in three important ways—scope (the relevant data not available), data quality, and ability to adjust for factors relating to patient case mix.1 2 3 4 5 6 This has led to the credibility of administrative databases being questioned, but as a result of …