How to conduct an acupuncture dose–effect relationship study? A discussion based on study methodology

Acupuncture therapy is widely used in the clinic, and its therapeutic effects have been proven by numerous studies. The dose–effect relationship of acupuncture is a fundamental aspect of the acupuncture research system. Recent studies found that different acupuncture dosages altered study results directly, indicating the importance of screening the optimal stimulation dosage. However, the system for studying the acupuncture dose–effect relationship is still in its infancy, and the methodology of the system needs to be improved. This review aimed to define the factors impacting acupuncture “dosage” and “effect,” and to improve the methodological system for research on the dose–effect relationship of acupuncture. By summarizing the current findings of acupuncture dose–effect studies, we discussed the vital acupuncture parameters and methodological problems that influence the relationship between acupuncture dosage and its effects. These factors consist of specific influencing factors (acupoint selection, acupuncture manipulation parameters, de qi response) and nonspecific influencing factors (comparison selection, blinding procedure, patient expectancy). Our perspectives offer suggestions for the design of acupuncture dosage–effect trials. Further studies need to be conducted to establish the methodological system and provide systematic evidence of the acupuncture dose–effect relationship. Graphical abstract: http://links.lww.com/AHM/A37