Putting confidence into audit: Using confidence intervals to set objective standards in primary care audits

Aim: To develop an objective method of setting audit standards in primary care. Design: Three audits of adult health surveillance were conducted using information taken from patients' records. Both audits recorded the proportions of notes containing a smoking history, alcohol consumption and blood pressure screening. Setting: A mixed urban/rural, non-fundholding practice of four GPs and one GP registrar with a list size of 7100 patients. Results: Confidence intervals were calculated on the data taken from the first audit. These were used as a standard by which to compare the performance levels measured in the subsequent audit. Conclusion: Using confidence intervals as a means of setting objective, evolving targets in audit is a more useful way of measuring the performance of individual general practices than using arbitrary standards.