Assessing morphological characteristics within traditional Chinese tongue diagnosis—A reliability study

Abstract

Background The assessment of the patient's tongue is a crucial diagnostic tool in traditional Chinese medicine. However, the reliability and validity of tongue diagnosis has rarely been investigated. As a first step in what we hope will develop to a series of studies on tongue diagnosis we investigated the reliability of the assessment of morphological characteristics. Methods A random sample of digital tongue photographs from 101 patients was taken from a larger database in a hospital for traditional Chinese medicine in Kotzting, Germany. Three (two Chinese, one German) physicians with extensive experience in tongue diagnosis independently assessed 14 morphological items selected after two small pilot series. Inter-rater reliability was assessed with Cohen's kappa (classification of agreement: 0.74 excellent). Results Kappa-values for the 14 items (× three pairs of raters=42 kappa values) covered a broad range from 0.17 to 0.89. Agreement was classified as poor in 12 comparisons, as moderate in 20, as good in 4 and as excellent in 6 comparisons. Items with good or excellent agreement for all three pairs of raters were teeth prints and colour of tongue coating. Raters often disagreed whether spots were present (kappa Conclusions In this study agreement in the assessment of morphological characteristics of the tongue between three experienced raters was highly variable. Assessments were performed under clinical conditions with limited standardized instructions for decisions. Agreement could probably be increased considerably with intense standardization; however, this does not seem to reflect normal clinical conditions.