Multicenter Comparison of Two Clinical Decision Rules for the Use of Radiography in Acute, High-Risk Knee Injuries,☆☆,

Presented at the Society for Academic Emergency Medicine Annual Meeting, Denver, CO, May 1996.
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Abstract

Study objective: Two separate clinical decision rules, one developed in Ottawa and the other in Pittsburgh, for the use of radiography in acute knee injuries have been previously validated and published. In this study, the rules were prospectively validated and compared in a new set of patients.

Methods: A prospective, blinded, multicenter trial was conducted in the emergency departments of three urban teaching hospitals. A convenience sample of 934 patients with knee pain requiring radiographs was enrolled. A standardized data form was completed for each patient, comprising the 10 clinical variables included in the two rules. Standard knee radiographs were then taken in each patient. The rules were interpreted by the primary investigator on the basis of the data sheet and the final radiologist radiograph reading.

Results: In the 745 patients in whom the Pittsburgh rules could be applied there were 91 fractures (12.2%). The use of the Pittsburgh rule missed one fracture, yielding a sensitivity of 99% (95% confidence interval [CI], 94% to 100%); the specificity was 60% (95% CI, 56% to 64%). The Ottawa inclusion criteria were met by 750 patients, with 87 fractures (11.6%). The Ottawa rule missed three fractures, for a sensitivity of 97% (95% CI, 90% to 99%); specificity was 27% (95% CI, 23% to 30%).

Conclusion: Prospective validation and comparison found the Pittsburgh rule for knee radiographs to be more specific without loss of sensitivity compared with the Ottawa rule.

[Seaberg DC, Yealy DM, Lukens T, Auble T, Mathias S: Multicenter comparison of two clinical decision rules for the use of radiography in acute, high-risk knee injuries. Ann Emerg Med July 1998; 32:8-13.]

Section snippets

INTRODUCTION

Patients with acute knee injuries are common in the ED, accounting for up to 1 million visits annually.1 Previous studies have shown that up to 85% of patients undergo radiography2; however, in only 6% to 12%3, 4, 5 are fractures actually identified. Despite this low incidence, it is common practice in many institutions to perform radiography in all traumatic knee injuries.

This conservative approach to the assessment of the knee results in many unnecessary radiographs, meaning potential excess

MATERIALS AND METHODS

We designed a prospective, blinded, multicenter validation-and-comparison trial in the EDs of three teaching hospitals: Mercy Hospital of Pittsburgh, the University of Pittsburgh Medical Center, and MetroHealth Medical Center in Cleveland. The study protocol was approved by the institutional review boards of all three hospitals. The requirement for written informed consent was waived because no intervention was performed and the data were kept confidential.

The study population was a convenience

RESULTS

Overall, 934 patients (ages range, 6 to 96 years) were enrolled into the study over an 18-month period. Table 1 lists the ED diagnoses of all patients. Contusions, sprains, and strains accounted for 77% of the total diagnoses. We noted 103 fractures (11%); tibial plateau and patellar fractures were the most common (Table 2).

. Knee fractures (N=103).

LocationNo. (%)
Tibial plateau41 (40)
Patella36 (34)
Femoral condyle11 (11)
Fibular head10 (10)
Tibial spine4 (4)
Salter II1 (1)

For the PGH rule, we

DISCUSSION

Clinical decision rules (prediction rules) reduce the uncertainty in patient care for both diagnostic and therapeutic decisionmaking. Methodologic standards for the development and testing of clinical decision rules are well-established.7, 10 Several clinical decision rules for the use of radiography in knee injuries have been developed in the last several years.3, 4, 5, 11, 12 The two rules with the largest validation cohorts were compared in our study. Both clinical decision rules were highly

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From the University of Florida Health Science Center, Jacksonville, FL*; the University of Pittsburgh Medical Center and Mercy Hospital,§ Pittsburgh, PA; and MetroHealth Medical Center, Cleveland, OH.II

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Reprint no. 47/1/90757

Address for reprints: David C Seaberg, MD, Division of Emergency Medicine, University of Florida Health Science Center, 655 West Eighth Street, Jacksonville, FL 32209

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