Patients not included in medical audit have a worse outcome than those included.

The aim of the present investigation was to analyse a clinical database in order to see how many patients were not included in medical audit and to see whether the outcome of the non-registered patients differed from that of the registered patients. Two independent surgeons studied the records of all infrainguinal bypass operations performed at six vascular surgical departments over a three-year period. A total of 684 bypass operations was reported to the register, of which 636 could be reviewed. One-hundred and twenty-eight cases that had not been reported were found from other sources. The outcome variables were mortality, amputation rate and patency. Sixteen per cent of eligible cases had not been reported. Mortality and amputation rate were twice as high among the missing cases as among the reported cases. There was no difference in patency. Overall judgement of the performance of an individual department may be impaired by cases not included in the register.