Re-evaluating the diagnostic accuracy of the tongue blade test: still useful as a screening tool for mandibular fractures?

BACKGROUND

Mandibular fractures are one of the most frequently seen injuries in trauma. In terms of facial trauma, mandible fractures constitute 40%-62% of all facial bone fractures. The tongue blade test (TBT) has been shown to be a sensitive screening tool when compared with plain films. However, recent studies have demonstrated that computed tomography (CT) scan is more sensitive for determining mandible fractures than the traditionally used plain films.

OBJECTIVE

The purpose of the study was to determine the sensitivity and specificity of the TBT as compared with the new gold standard of radiologic imaging, CT scan.

METHODS

Any patient suffering from facial trauma was prospectively enrolled during the study period (August 1, 2010 to April 11, 2012) at a single urban, academic Emergency Department. A TBT was performed by the resident physician and confirmed by the supervising attending. CT facial bones were then obtained for the ultimate diagnosis. Inter-rater reliability (κ) was calculated, along with sensitivity, specificity, negative predictive value, and likelihood ratio (-) based on a 2 × 2 contingency table generated.

RESULTS

During the study period, 190 patients were enrolled. Inter-rater reliability was κ = 0.96 (95% confidence interval [CI] 0.93-0.99). The following parameters were then calculated based on the contingency table: sensitivity 0.95 (95% CI 0.88-0.98), specificity 0.68 (95% CI 0.57-0.77), negative predictive value 0.92 (95% CI 0.82-0.97), and likelihood ratio (-) 0.07 (95% CI 0.03-0.18).

CONCLUSIONS

Based on the test characteristics calculated (negative predictive value 0.92, sensitivity 0.95, likelihood ratio -0.07), the TBT is a useful screening tool to determine the need for radiologic imaging.