MULTICENTER COMPARISON OF 2 CLINICAL DECISION RULES FOR THE USE OF RADIOGRAPHY IN ACUTE, HIGH-RISK KNEE INJURIES

Study objective: Two separate clinical decision rules, one developed i n Ottawa and the other in Pittsburgh, for the use of radiography in ac ute knee injuries have been previously validated and published. In thi s study, the rules were prospectively validated and compared in a new set of patients. Methods: A prospective, blinded, multicenter trial wa s conducted in the emergency departments of three urban teaching hospi tals. A convenience sample of 934 patients with knee pain requiring ra diographs was enrolled. A standardized data form was completed for eac h patient, comprising the 10 clinical variables included in the two ru les. Standard knee radiographs were then taken in each patient. The ru les were interpreted by the primary investigator on the basis of the d ata sheet and the final radiologist radiograph reading. Results: In th e 745 patients in whom he Pittsburgh rules could be applied there were 91 fractures (12.2%). The use of the Pittsburgh rule missed one fract ure, yielding a sensitivity of 99% (95% confidence interval [CI], 94% to 100%); the specificity was 60% (95% CI, 56% to 64%). The Ottawa inc lusion criteria were met by 750 patients, with 87 fractures (11.6%). T he Ottawa rule missed three fractures, for a sensitivity of 97% (95% C I, 90% to 99%); specificity was 27% (95% Cl, 23% to 30%). Conclusion: Prospective Validation and comparison found the Pittsburgh rule for kn ee radiographs to be more specific without loss of sensitivity compare d with the Ottawa rule.