Diagnosis of Occult Scaphoid Fractures: A Cost-Effectiveness Analysis.

BACKGROUND Scaphoid fractures are common but may be missed on initial radiographs. Advanced imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI) have improved diagnostic accuracy, but at an increased initial cost. The purpose of this study was to evaluate the cost-effectiveness of immediate advanced imaging for suspected occult scaphoid fractures. METHODS A decision analysis model was created to evaluate three diagnostic strategies for patients with concerning history and examination but negative radiographs: (1) empiric cast immobilization with orthopaedic follow-up and repeat radiography at two weeks post-injury, (2) immediate CT scanning, or (3) immediate MRI. Prevalence of occult scaphoid fracture, sensitivity and specificity of CT and MRI, and risks and outcomes of a missed fracture were derived from published clinical trials. Costs of imaging, lost worker productivity, and surgical costs of nonunion surgery were estimated on the basis of the literature. RESULTS Advanced imaging was dominant over empiric cast immobilization; advanced imaging had lower costs and its health outcomes were projected to be better than those of empiric cast immobilization. MRI was slightly more cost-effective than CT on the basis of the mean published diagnostic performance, but was highly sensitive to test performance characteristics. Advanced imaging would have to increase in cost to more than $2000 or decrease in sensitivity to <25% for CT or <32% for MRI for empiric cast immobilization to be cost-effective. CONCLUSIONS Given its relatively low cost and high diagnostic accuracy, advanced imaging for suspected scaphoid fractures in the setting of negative radiographs represents a cost-effective strategy for reducing both costs and morbidity. The decision to use CT compared with MRI is a function of individual institutional costs and local test performance characteristics.