Objective

To investigate the distribution characteristics of syndrome types of traditional Chinese medicine (TCM) in essential hypertension and to explore the distribution rule of TCM syndromes.
Methods

 A multicenter, large-sample survey method of clinical epidemiology was applied to choose the patients with essential hypertension from North, Middle, and South China. A questionnaire was designed and filled in, then 477 untreated patients with first-diagnosed essential hypertension were selected and the information was recorded into FileMaker database. A cluster analysis method was utilized to study the TCM syndrome distribution rule of essential hypertension.
Results

Two-step cluster analysis was done from 3 to 7 clusters. Seven clusters were appropriate, which included deficiency of heart and kidney qi, hyperactivity of liver-yang, deficiency of yin and yang, stagnation of phlegm-dampness, phlegm-heat (subtype of stagnation of phlegm-dampness), blood stasis obstructing collaterals, and other syndromes. The symptoms presenting high percentage in each cluster were more significant in TCM theory. The syndromes of hyperactivity of liver-yang (24.1%) and stagnation of phlegm-dampness (27.1%) presented the high percentages, and deficiency of heart and kidney qi (10.1%), deficiency of yin and yang (8.4%), and blood stasis obstructing collaterals (9.0%) presented the low percentages.
Conclusion

As compared with the current syndrome differentiation criteria, two-step cluster analysis results not only include the syndromes of deficiency of yin and yang, hyperactivity of liver-yang, stagnation of phlegm-dampness, but also cover qi deficiency and blood stasis.

Key words: Hypertension, Syndrome, Questionnaires, Survey methods, Cluster analysis, Clinical study, Evidence-based medicine