[On the reliability of the description of morphological characteristics in traditional Chinese tongue diagnostics]

Abstract

Background and objective: The assessment of the tongue is a crucial diagnostic tool of traditional Chinese medicine. In a series of studies we aimed to investigate to what extent independent raters agree in the description of morphological tongue characteristics.

Methods: In two pilot studies (n = 15 each) and one larger study (n= 101) two to three physicians experienced in traditional Chinese medicine assessed morphological characteristics in digital photos of tongues by use of a rating form and under blind conditions. The primary outcome measure was agreement beyond chance (Cohen's kappa).

Results: Kappa values varied strongly in the first pilot study(-0.15 to 0.76) and for many items, agreement was weak or moderate. In the second pilot study which used improved methods kappa values still varied considerably(-0.10 to 1.00), but for 7 out of the 18 items assessed there was an excellent agreement (kappa > or =0.75). In the confirmatory study, kappa values ranged between 0.15 and 0.83.

Discussion: The performed studies have to be seen as a first attempt to develop adequate methods in order to systematically investigate the reliability of traditional Chinese tongue diagnostics. The study findings suggest that the description of morphological characteristics within traditional Chinese tongue diagnostics has acceptable reliability.