Objective: To determine whether it is possible to decrease the number of X-rays in acute ankle injury while keeping the health care constant, using a scoring system.
Design: Prospective.
Method: Patients presenting in the emergency department of the University Hospital Utrecht (AZU), the Netherlands, over a one-year period of time with acute ankle injuries were subjected to a thorough physical examination based on a scoring system developed at Leiden University Hospital. The score was calculated and X-ray examination was indicated when this score was > or = 8 points. Radiological investigation or telephone interviews six weeks after injury achieved verification of the clinically relevant ankle fractures. Specificity and sensitivity were calculated from every possible cut-off point and drawn in a 'receiver operating characteristics' (ROC) curve.
Results: Of the 514 patients included 81 patients had a score of 8 or higher and 24 of them had a clinically relevant fracture. In 34 patients an ankle X-ray was made although their score was < 8 points. The positive and negative predictive values of the system were 30% (95% confidence interval (95% CI): 20-41) and 99% (95% CI: 97-100) respectively. The score yielded an area under the ROC curve of 91% (95% CI: 84-98). A cut-off point of 8 led to a reduction of X-rays by 60% (using the 'Ottawa ankle rules' the decrease in this population would have been 28%). On the other hand, 5 clinically relevant fractures were missed.
Conclusion: Radiological examination in patients wit acute ankle complaints was reduced while health care remained almost constant. In the AZU, a decision was made for a major reduction in X-rays while accepting that some fractures would be missed.