Diagnostic accuracy of tongue coating in identifying acute appendicitis: a prospective cohort study.

Abstract

Background: Acute appendicitis requires timely diagnosis. The diagnostic efficacy of tongue examination in making this diagnosis has not been established. This study investigates whether the Tongue Coating Index (TCI), a validated measure of tongue coating, can aid in diagnosing acute appendicitis.

Methods: We conducted a prospective cohort study (1 September 2018-31 December 2020) at a single Japanese hospital. Adults (≥20 years) with suspected acute appendicitis, presenting to either the emergency department or general outpatient clinic, were enrolled. Tongue images were taken at presentation; two independent examiners-unrelated to clinical care and blinded to patient data-later scored these images using the TCI. A composite reference standard (clinical findings, imaging, histopathology, follow-up) was used to confirm appendicitis. We compared the TCI's diagnostic performance with the Alvarado score and its components using C-index, area under the curve (AUC), sensitivity and specificity.

Results: Of 145 included patients, 69 (47.6%) were diagnosed with acute appendicitis. The TCI demonstrated comparable discriminative ability (C-index AUC 0.62; 95% CI, 0.53 to 0.71) to that of the Alvarado score (0.66; 95% CI, 0.57 to 0.75). Of Alvarado score components, migration of pain had an AUC of 0.63 (95% CI, 0.55 to 0.71), anorexia 0.58 (95% CI, 0.50 to 0.66) and tenderness in the right lower quadrant 0.55 (95% CI, 0.50 to 0.60). At a cut-off of 3, the TCI demonstrated high sensitivity of 96% (95% CI, 88% to 98%) but low specificity of 21% (95% CI, 13% to 32%). Conversely, at a cut-off of 10, the TCI showed increased specificity of 83% (95% CI, 73% to 90%) but reduced sensitivity of 29% (95% CI, 20% to 41%).

Conclusion: The TCI showed comparable diagnostic performance to the Alvarado score and its individual components. TCI may potentially serve as an additional non-invasive indicator for diagnosing or ruling out acute appendicitis. Further research is essential to validate its clinical utility.