Correlation between tongue body colour, as quantified by machine learning, and clinical indices

Abstract

ObjectivesEvaluation of tongue colour is an important approach for assessment of human health in traditional East Asian medicine, which originated in ancient China. However, tongue colour analyses are unreliable due to poor quantification and reproducibility. Given these limitations, the utility of this technique as a clinical index has not been demonstrated. Here, we assessed whether tongue colour evaluations, as performed in Kampo (traditional Japanese) medicine, via an automated image acquisition system were associated with particular indices of patient health. MethodsWe obtained high colour reproduction tongue images from 816 Japanese subjects and applied a machine-learning analysis approach to the quantification of tongue body colour in them. Data on sex, age, systolic blood pressure, diastolic blood pressure, pulse rate (PR), body temperature, body mass index (BMI), past medical history (PMH), and blood examination results (haemoglobin, Hb; creatinine) were also collected. ResultsTongue body colour was influenced by multiple clinical indices, per simple correlation analyses. In particular, sex, age, BMI, PR, and Hb were correlated with tongue body colour. No significant correlation with PMH was found. ConclusionsTongue body colour, as quantified with a machine learning approach, was found to be a clinical predictor of changes in several clinical indices, particularly those related to obesity and haemoglobin concentrations.