The influence of referral protocols on the utilization of magnetic resonance imaging: evidence from Manitoba.

The relative scarcity of magnetic resonance imaging (MRI) capacity in most Canadian jurisdictions has created pressures to develop guidelines on appropriate clinical indications for examination by this method. The objective of this study was to assess the influence of referral protocols on the utilization of MRI services. Three neuroradiologists and one radiologist reviewed the indications for MRI for 198 referrals to the facility at St. Boniface General Hospital in Winnipeg (99 from outside Manitoba and 99 from within the province), selected at random from patients seen between Jan. 1 and Dec. 31, 1991, for suspected disorder of the brain or the spine. Out-of-province referrals had not been subject to referral protocols, whereas those from within Manitoba had been subject to such protocols. At least three of the four radiologists agreed on whether an examination was appropriate in 175 of the 198 cases (88.4%). Out-of-province referrals were significantly more likely to be considered inappropriate for MRI: 24 (24%) of the referrals from outside Manitoba were judged inappropriate by three or more reviewers, whereas only 10 (10%) of the referrals from within Manitoba were judged inappropriate (chi 2, p < 0.01). Of the 19 cases that were judged inappropriate for MRI by three or more reviewers and that yielded abnormal findings, unique clinical information was derived from the examination in only 1 (5%); in contrast, of the 85 cases that were judged appropriate for MRI by three or more reviewers and that yielded abnormal findings, unique information was found in 47 (55%).(ABSTRACT TRUNCATED AT 250 WORDS)