[Study on traditional Chinese medicine common syndrome characteristic of coronavirus disease 2019 based on latent structure combined with system clustering analysis]

Objective: To investigate traditional Chinese medicine (TCM) common syndrome characteristic of coronavirus disease 2019 (COVID-19), thus providing evidence for clinical differentiation.

Methods: The COVID-19 TCM treatment plan and syndrome related literature published before February 24, 2020 was searched and a database was established. TCM common syndrome characteristics of COVID-19 were analyzed by the method of latent structure and system clustering combined with frequency and constituent ratio, which were conducted by Lantern 5.0 and SPSS 20.0.

Results: Forty-two literatures about treatment plans, and 212 syndromes records were enrolled. Latent structure model was established based on 53 symptoms with frequency over 10, and 14 latent variables and 7 syndromes were concluded by comprehensive clustering, including syndrome of pathogenic heat invading lung, internal block and outward desertion, syndrome of dampness heat accumulating lung, syndrome of Qi and Yin deficiency, syndrome of epidemic virus closing lung, syndrome of cold dampness closing lung and syndrome of Qi deficiency of lung and spleen. Factor analysis was conducted for 53 symptoms, which were reported more than 10 times, and 14 common factors were obtained. Symptoms with load coefficient over 0.3 were clustered and 6 syndromes were obtained, including syndrome of epidemic virus closing lung, syndrome of pathogenic heat invading lung, syndrome of Qi and Yin deficiency, internal block and outward desertion, syndrome of cold dampness closing lung, and syndrome of dampness heat accumulating lung. The literatures included 25 syndromes, and the syndromes with constituent ratio over 5% were internal block and outward desertion (14.62%), syndrome of epidemic virus closing lung (13.68%), syndrome of dampness heat accumulating lung (12.74%), syndrome of Qi deficiency of lung (10.85%), spleen and syndrome of cold dampness closing lung (8.50%), syndrome of Qi and Yin deficiency (8.50%), syndrome of pathogenic heat invading lung (8.02%) and syndrome of dampness repressing defensive Qi of lung (5.66%). Eighty-seven symptoms whose cumulative frequency was 2 838 were referred, including greasy fur (5.25%), fever (4.83%), red tongue (4.37%), rapid pulse (3.74%) and fatigue (3.46%). According to the results above, the common syndromes and their symptoms of COVID-19 were: (1) syndrome of pathogenic heat invading lung: fever, cough, throat-drying, headache, all of the body distressed and constipation, etc.; (2) syndrome of cold dampness closing lung: aversion to cold, all of the body distressed, nausea and vomiting, abdominal distention and loose stool, etc.; (3) syndrome of dampness heat accumulating lung: cough, sticky phlegm, anorexia, thirst without desire to drink and constipation, etc.; (4) syndrome of epidemic virus closing lung: fever, cough, yellow phlegm, wheezing, suffocation and purple lips, etc.; (5) internal block and outward desertion: coma, feel fidgety, suffocation, sweating and feel cold and purple lips, etc.; (6) syndrome of Qi and Yin deficiency: dry cough, sweating, fatigue, thirsty, feverish feeling in palms and soles and loose stool, etc.; (7) syndrome of Qi deficiency of lung and spleen: cough, wheezing, sweating, fatigue, nausea and vomiting, and loose stool, et al.

Conclusions: The common syndromes of COVID-19 were syndrome of pathogenic heat invading lung, syndrome of cold dampness closing lung, syndrome of dampness heat accumulating lung, syndrome of epidemic virus closing lung, internal block and outward desertion, syndrome of Qi and Yin deficiency and syndrome of Qi deficiency of lung and spleen. This study could provide reference for clinical differentiation.