Two Phase Derivation / Validation of Clinical Decision Criteria for Finger Radiographs

Background: A litany of clinical decision rules have been developed to decrease unnecessary emergency department radiography, but there are few clinical guidelines or decision criteria established for the taking of finger radiographs. Objective: To develop criteria for a clinical decision rule for finger radiographs. Methods: This was a two-phase derivation/validation development of clinical decision rules for finger radiographs. The derivation phase was a retrospective chart review of all ED patients with acute finger and hand injuries. Patients were included based on select ICD-9 codes for finger injuries, age >18 years, and utilization of x-ray to rule out fracture. Demographics, mechanism of injury, physical exam findings, and past medical history were first individually evaluated using a univariate procedure, verifying all assumptions for independence, checking for collinearity, and probability of fracture on radiographs. A logistic model was built using forward and backward elimination, examining assumptions for statistical and clinical reasonableness at each point. Categorical data were compared for association using the Fishers Exact Test. Once derived, the model was validated on a second cohort of ED patients using the same inclusion criteria. Results: In Phase I (derivation), 394 patients were included representing 186 finger fractures. Of all the demographic, historical and physical exam findings analyzed, only patient gender, location of injury and range of motion were statistically significantly correlated (p