Psychophysical responses in patients receiving a mock laser within context of an acupuncture clinical trial: an interoceptive perspective

Abstract

Background: The psychophysical responses induced by verum acupuncture are characterized by a constellation of unique subjective sensory responses commonly termed De Qi. Furthermore, a variety of sham interventions have been used as a control for acupuncture clinical trials. Indeed, one such control has been mock laser which has been used as control intervention in several acupuncture clinical controlled trials. The current study aim was to examine the De Qi sensory responses and its related characteristics elicited from acupuncture and compare them to those reported following sham laser in participants enrolled in a clinical trial.

Methods: The study was embedded in a multi-center, two-arm randomised clinical trial, which evaluated the effect of acupuncture on lateral elbow pain. De Qi was assessed using the Massachusetts General Hospital Acupuncture Sensation Scale (MASS). Ninety-six participants were randomly allocated to receive either acupuncture (n = 47) or mock laser (n = 49) at the acupoints LI 10 and LI 11.

Results: Participants in both intervention groups reported similar De Qi psychophysical characteristics; however, both intensity and frequency of the individually perceived De Qi characteristics were significantly higher in the acupuncture group. 'Soreness', 'deep pressure', and 'fullness-distension' in the acupuncture group and 'tingling', and 'sharp pain' in mock laser group, were identified as the leading characteristics. Similar level of MASS De Qi Index (MDI) scores were reported for 'Hong Kong-China' and 'Australia-Italy' with a significantly higher level of De Qi reported by 'Hong Kong-China'. Furthermore, two distinct De Qi categories were identified, namely De Qi (in line with classical sensory responses of Suan, Ma, Zhang, and Zhong) and pain.

Conclusions: Subjective 'somatic or interoceptive awareness' should be taken into account when De Qi psychophysical responses are examined. The study accentuates the necessity and the significance of further research into interoception phenomenon which may contribute to a better understanding of the placebo effect and De Qi psychophysical responses.

Trial registration: Australian and New Zealand Clinical Trial Registry reference: ACTRN12613001138774 on 11th of October 2013.

Keywords: Acupuncture; De Qi; Interoceptive; Mock laser; Psychophysical responses.

Fig. 1

Flowchart of the trial

Fig. 2

a indicated the manual needle manipulation at acupoint LI11 followed by LI10 on the affected side. First time Manipulation (M1); Second time Manipulation (M2); Rest period (R). b indicated the use of inactive mock laser probe on the same acupoints to acupuncture group at different time interval; First time Probe Touch (PT1); Second time Probe Touch (PT2); Rest period (R)

Fig. 3

a and b MASS De Qi Index (MDI) scores for the treatment and control group at session 1 and session 9 respectively, (n = 47 for the treatment group, n = 37 for the control group). The boxes are bound by the interquartile range (IQR) (top of the box represents the 75th percentile, while the bottom of the box represents the 25th percentile). The boxes are divided by the median, and the whiskers attached to the box represent the minimum and maximum scores. ***: statistically significant difference (p < 0.001) between the two groups

Fig. 4

a and b MASS De Qi difference among trial sites for the acupuncture group a and the mock laser group b individually. The box plots demonstrate comparison of the MASS De Qi median scores between the four trial sites for both the acupuncture group (HK = 22, AUS = 24, CHA = 24, ITY = 24) and the mock laser group (HK = 26, AUS = 24, ITY = 24). One trial site (China) did not collect data for the mock laser group. Bonferroni correction for multiple comparisons was used. Pairwise comparison demonstrated statistically significant differences in the MDI scores across different trial sites (Kruskal-Wallis Rank Sum test, * p < 0.05, **p < 0.01, ***p < 0.001; 2-tailed). Extreme values and outliers lied beyond the whiskers and denoted differently with a star and a circle respectively

Fig. 5

Comparison of the frequency of individual De Qi psychophysical responses during acupuncture and mock laser intervention. Data for weeks were pooled together. Frequencies calculated upon the number of participants reporting perceptions within each study arm (n = 47 for the acupuncture group, n = 37 for the mock laser group). Data related to mock laser group (Centre 3) was excluded from data analysis. Each De Qi characteristic was shown on a Likert scale rating (0-10); In all cases the expected frequencies were less than five in each cell and therefore Fisher Exact test was used, * p < 0.05, **p < 0.01, ***p < 0.001

Fig. 6

a-l Comparison of individual De Qi characteristics across the two study groups (acupuncture and mock laser). MASS De Qi score for the acupuncture and mock laser group at the session 1 and session 9, (n = 47 for the acupuncture group, n = 38 for the mock laser group). The boxes are bound by the interquartile range (IQR) (top of box represents the 75th percentile, while the bottom of the box represents the 25th percentile). The boxes are divided by the median, and the whiskers attached to the box represent the minimum and maximum scores. Extreme values and outliers lied beyond the whiskers and denoted differently with a star and a circle respectively