Cluster Analysis for Disease Etiology
The cluster analysis identified 9 research hotspots for GERD etiology (Fig. 4):
ⅰ) Internal injury diet. It is the earliest appeared etiology and has received continuous attention which accompanied with fluid retention and internal injury by raw and cold food. The high-frequency words mainly contain internal injury diet, insufficiency of natural endowment, hunger and fullness, hot nature diet, exogenous wind-cold, spleen deficiency, misuse of spicy, more impatience and anger, seven emotions stimulating, internal Injury food and drink, internal injury milk, fire phlegm, excessive stomach Qi, injury to spleen and stomach by erroneous purgation, stomach cold, ascendant rising of stomach fire/stomach fire rising, deficient cold of spleen and stomach, typhoid fever malaria and Yin of stomach injury, injury to spleen by stagnant wood, liver Qi stagnation, exogenous summer-heat and damp, improper diet and overstrain, hot phlegm, exterior syndrome of febrile disease accompanying dyspepsia, extreme cold, stagnation of qi activity and food retention.
ⅱ) Pathogenic factor of gallbladder. It was appeared in the 11th century (Northern Song Dynasty) and disappeared in the mid-16th century (Ming Dynasty).The high-frequency words are recovery of YangMing qi, dry evil pathogenic features, think of emotion, reversed flow of YangMing qi, dryness of climate affecting gallbladder, preponderance of YangMing qi, pathogenic factor of gallbladder.
ⅲ) Internal injury due to emotional disorder. It was appeared in the 12th century (Southern Song Dynasty). The high-frequency keywords contain weakness of spleen qi, internal injury due to emotional disorder, worries affecting qi, spleen-stomach deficiency, thinking, external infection of four seasons, sufficiency of natural endowment, phlegm-dampness, thinking resulting disorder of blood.
ⅳ) Food retention. It was appeared in the 13th century (Yuan Dynasty) and faded out in the mid-18th century (Qing Dynasty). The high-frequency keywords are improper diet, liver-qi depression, the spleen wet not shipped, heat stagnation, food retention, stomach heat, dampness-heat with cold food, fondness of liquor, moodiness, excessive deliberation, heat stagnation of spleen and stomach, deficiency of qi and blood, qi stagnation.
ⅴ) Heat stagnation of body fluid. It was appeared in the 13th century (Yuan Dynasty). The high-frequency keywords are internal injuries of cold content, heat stagnation of body fluid, phlegm and retained fluid, internal injury diet and digestive disorders, dampness-heat of spleen and stomach and invasion of wind-cold, weakness of middle qi and heat stagnation of phlegm and retained fluid, phlegm-fire, fire stagnation, preponderance of ShaoYang qi, macronosia generating insufficiency of the spleen, qi deficiency due to oldness, phlegm stagnation generating acid, external cold and interior heat, external, heat stagnation of food.
ⅵ) Incoordination between the spleen and stomach. It was also appeared in the 13th century (Yuan Dynasty). The high-frequency keywords are food retention, cold pathogenic disease with food retention, incoordination between the spleen and the stomach, stomach fire, heat stagnation of body fluid at lung and stomach, food stagnation and phlegm, hot origin cold end, internal heat stagnation and outside wind-cold, cold in upper-jiao, spleen deficiency generating cold, stomach cold, internal cold, gastric disorder with wind-damp.
ⅶ) Damp-heat syndrome of stomach. It was appeared in the 15th century (early Ming Dynasty). The high-frequency keywords contain damp-heat syndrome of stomach, damp-heat, liver-fire, dyspepsia caused by excessive eating or improper diet, weakness of stomach qi, weakness and cold of stomach qi, insufficiency of qi and blood and deficiency of spleen-stomach after parturition, deficiency of spleen Yang, stagnation of liver qi, phlegm-fire confusing heart stagnate at stomach, accumulation of dry feces.
ⅷ) Phlegm-fire. It was appeared in the 16th century (mid-Ming Dynasty). The high frequency key words contain phlegm-fire, deficiency of heart blood, mistreatment injuring spleen, insufficiency of middle qi, phlegm-dampness and qi constraint, consumptive disease, deficiency of spleen yin, blood-insufficiency and stomach heat, deficiency of spleen yin and heart yin, food retention, essence derived from food stagnation, Qi stagnation, phlegm stagnation, indigestion due to intestinal worm.
ⅸ) Cold evil invading the stomach. It was also appeared in the 16th century (mid-Ming Dynasty), accompanied with stomach deficiency. The high-frequency keywords contain food retention, lodged rheum generating heat stagnation, cold evil invading the stomach, excessive acid, deficiency of both spleen and kidney, internal injury diet, phlegm stagnation of middle-jiao, after cold pathogenic disease, indigestion-induced heat stagnation, deficiency-cold,fire deficiency generating reduction of soil productivity.
Qualitative Literature Analysis for Disease Etiology
The < Huang Di nei jing > first proposed the disease etiology is ‘the evil in gallbladder and reversed flow of evil at stomach’ or ‘the recovery of Yang Ming Year’. In the Sui and Tang dynasties, the etiology was classified as ‘Phlegm and fluid retention’ which includes phlegm, cold phlegm, stomach deficiency phlegm stagnation, retained fluid, and ‘Diet’ which includes food of internal injury, food retention, alcohol addiction with food retention.
From the Song Dynasty, the etiological studies enriched significantly and mainly proposed the following six categories: a) Five evolution stages and six climatic factors. It is similar to ‘theory of circulatory phases’ in < Huang Di nei jing>. The < Su Wen Yao Zhi Lun > stated ‘When dryness recovery, purification qi prevail, ..., vomiting, cough, hiccups, and upset, disease in the diaphragm’, ‘When Yang Ming qi recovery, purification qi prevail, ..., vomiting, cough, hiccups, and upset”, written by Ma Zongsu in the Yuan Dynasty. In the Ming Dynasty, Lou Ying and Xu Chunfu believed that ‘the recovery of YangMing, often sigh and vomiting.’ b) Diet. The < The Three for Extremely-Disease and Syndrome Party Theory > stated ‘When there is retained fluid, it makes epigastric upset; when there is lodging food, which cause acid regurgitation’, written by Chen Yan in the Song Dynasty. Yan Yonghe explained more exactly in his book < Yan's Ji Sheng Fang > as ‘If you are insufficiency of natural endowment, when you are hungry or lose your appetite, or after a meal with five flavors, fishy fish, cheese, raw and cold fruits and vegetables, those will stop storing the stomach, and then you will suffer from stagnation, acid regurgitation and vomit.’ c) Mistreatment injuring spleen. In the Ming Dynasty, Zhang Jingyue putted forward that the spleen and stomach can be injured by misusing of digestive or attack medicines which results in epigastric upset. In The Ming Dynasty, <Concise Medicine Sufficient > stated ‘there are also misuse of medicines such as helping digestion and removing accumulation, deficiency of spleen and stomach, less blood and epigastric upset, deficiency of middle-jiao and upset accompanying not hungry’, written by Sun Zhihong. d) Internal injury due to emotional disorder and liver-qi depression. Zhu Danxi putted forward that phlegm accumulation caused by qi disease is the cause of acid regurgitation, because too much worry could result in stagnation of qi activity, then the liver depression restrict spleen and touch off acid regurgitation. e) Exposure to exogenous cold. The < Zheng Zhi Hui Bu > stated that ‘normally stagnant body fluid caused dampness-heat; when the wind-cold, internal heat stagnation and outside wind-cold, the epigastric upset it will be and the sour taste will sting the heart’ which refers to the external wind-cold; and ‘if the cold evil invading the stomach, suddenly into acid, heat transformed from cold, the acid belongs to the cold also’ which refers to the cold evil invading the stomach, written by Li Yongcui in the Qing Dynasty. f) Spleen-stomach deficiency. The < Hua Tuo Shen Fang > proposed the disease of Spleen Deficiency which is characterized by sallow of complexion due to spleen disorders; stiff tongue, poor appetite, vomiting, weakness of limbs due to superabundance; and frequent disorders, acid regurgitation, uncured dysentery due to deficiency.