Effects of mailed dissemination of the Royal College of Radiologists' guidelines on general practitioner referrals for radiography: a time series analysis.

Aim: To evaluate the effect of postal dissemination of the third edition of the Royal College of Radiologists' (RCR) guidelines on general practitioner referrals for radiography.

Materials And Methods: An interrupted time series using monthly data for 34 months before and 14 months after dissemination of the guidelines was employed. Data were abstracted for the period April 1994 to March 1998 from the computerized administrative systems of open access radiological services provided by two teaching hospitals in one region of Scotland. The time series results are contrasted with those obtained by using a simple before and after design.

Results: A total of 117 747 imaging requests from general practice were received in the two departments. There were no significant effects of disseminating the guidelines on the total number of requests, or on requests for individual examinations. If a simple before and after study had been used, then we would have erroneously concluded that significant changes had occurred in referral practice for 11 of the 18 procedures concerned.

Conclusion: Mailing of copies of the RCR guidelines had a small effect on general practitioners' use of X-ray investigations of uncertain clinical significance. Additional dissemination and implementation strategies appear necessary to promote the use of guidelines.