Identifying Dose Components of Manual Acupuncture to Determine the Dose–Response Relationship of Acupuncture Treatment: A Systematic Review

The dose–response relationship is a hallmark of pharmacological studies. However, this relationship has not been fully established in acupuncture research. This systematic review aims to provide the characteristics of the dose–response relationship in acupuncture research. We further summarized the differences in acupuncture effects according to dose components. Dose components of acupuncture were categorized into three groups: number of needles, stimulation intensity, and total number/frequency of treatments. The PubMed database was used to identify studies examining the effects of different doses of acupuncture from the establishment of the database to August 13, 2020. Dose components and responses were extracted from each study, and the results of low- and high-dose conditions were compared. Fourteen studies were included in this study. Of the included studies, 37.5% showed statistically significant enhanced responses to acupuncture treatment under high-dose conditions compared to low-dose conditions. Significant differences between high- and low-dose conditions were observed most frequently in studies that used various stimulation intensities (four out of six studies), followed in order by studies that used various numbers of needles (two out of seven studies), and those that used various numbers or frequencies of treatment (none of the three studies). Responses were categorized into symptom changes, physiological changes, experimentally induced pain/stimuli perception, and needling sensation. Stimulation intensity, which is considered one of the most important needling components, might indeed have a great impact on clinical responses to acupuncture.