Developing priority criteria for magnetic resonance imaging: results from the Western Canada Waiting List Project.

OBJECTIVE The Western Canada Waiting List (WCWL) Project is a federally funded partnership of 19 organizations, including medical associations, health authorities, ministries of health and research organizations, that was created to develop tools to assist in assessing the relative urgency and priority of patients on waiting lists. The WCWL panel on magnetic resonance imaging (MRI) was 1 of 5 panels constituted under this project. METHODS The panel developed and tested a set of standardized clinical criteria for setting priorities among patients awaiting MRI. The criteria were applied to 407 patients in the 4 western provinces. Regression analysis was used to determine the set of criteria weights that collectively best predicted clinicians' overall ratings of patients' urgency for MRI. Reliability was assessed using clinicians' ratings of 6 hypothetical paper cases. RESULTS The resulting weighted criteria accounted for about two-fifths of the observed variance in overall urgency ratings (R2 = 39.9%). The panel then modified the criteria on the basis of regression results and clinical judgment. Most of the revised criteria items showed poor inter-rater reliability, but test-retest reliability (over a 2-month interval) was relatively good. CONCLUSION Criteria items requiring probability judgments were a challenge for clinicians. Further development and testing of the tool appears warranted, although considerable question remains concerning the utility of priority criteria for MRI and other diagnostic services.