Tongue features of patients with coronavirus disease 2019: a retrospective cross-sectional study

Traditional Chinese medicine (TCM) has been widely used in the treatment of coronavirus disease 2019 (COVID-19). Tongue features should be referred for diagnosis and treatment of diseases in TCM. Therefore, it is necessary to analyze the tongue features of the patients suffered from COVID-19.

COVID-19 Symptom Database (established by Evidence-based Medicine Center of Tianjin University of TCM) was searched for eligible tongue pictures. The tongue pictures were assessed by TCM experts to extract the data of tongue color, coating color, tongue body shape and coating proper feature. The relationship between tongue features and patient's condition was analyzed.

Patients diagnosed as mild and moderate COVID-19 commonly had light red tongue and white coating. Severe patients had purple tongue and yellow coating. The proportion of critical patients with tender tongue increased to 75%. Greasy coating was a significant characteristic of patients with COVID-19. The proportions of greasy coating were 53.33%, 73.30%, 83.67 and 87.5% in disease category of mild, moderate, severe and critical. In addition, the thick coating proportion increased from mild (24.89%) to critical (50.00%).

Tongue features have certain relationship with the category of COVID-19. Tongue features can serve as potential indicators for the evaluation of patient's condition and prognosis. Further studies are needed to enhance the quantification of tongue features and develop standards.