Decision Rules

Course of Action

A decision regarding referral or not for further testing is frequently required in clinical assessment. Referral may be to low-cost tests, as in the case of plain radiographs for identification of fracture, or to more expensive tests such as dual-energy X-ray absorptiometry to assess bone mineral density for osteoporosis screening. Clinical decision rules have demonstrated advantages over clinical judgment in these decisions. Further useful applications of clinical decision rules include guiding referral for cranial computed tomography for minor head injury and venous ultrasonography for lower-limb deep vein thrombosis.

Ankle and knee decision rules are examples of rules designed to explicitly suggest when to refer for radiography. The ankle and knee rules were developed to inform referral to radiography of patients with acute injury and potential fracture in primary care and emergency department settings. Impetus for development of ankle and knee decision rules arose from recognition that plain radiographs were commonly ordered for patients following ankle and knee blunt trauma from blows and falls, in the absence of fracture. High healthcare costs of unnecessary radiographs and patient time spent having the procedure were identified. Although the plain radiograph is relatively low cost, ankle and knee trauma are common, resulting in high volumes of ankle and knee radiographs and therefore substantial healthcare costs. Implementation of ankle and knee rules was intended to impact on these costs and lead to healthcare savings.

Concern of the clinician or, in some cases, the patient that a fracture may be missed can influence clinical decisions. Justification for these concerns is that if radiography is not ordered for a patient with a fracture, there could be serious consequences. Delayed or overlooked diagnosis of fracture can affect clinical outcome and may result in increased healthcare costs and lost productivity. A clinician who misses an ankle or knee fracture may be subject to claims of malpractice. For these reasons, acceptance of a rule by clinicians requires a [Page 300]guarantee that a rule will identify clinically important fractures.

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