Abstract
Background: Chronic low back pain (cLBP) is a global health complaint and also a dominant cause of disability. Acupuncture is an effective therapy for cLBP; however, evidence for an optimal acupuncture treatment regime is limited. The foundational Chinese medicine classic The Inner Canon of yellow emperor instructs practitioners to palpate the acupoint to find the most sensitive site before inserting needles. In pathological states, disease-related acupoints are believed to be activated, which is known as acupoint sensitization. The work reported in this thesis aimed to investigate the phenomena of acupoint sensitization in the context of cLBP, and the role of sensitized acupoints in the acupuncture treatment for cLBP.
Methods: A systematic and stepwise approach recommended in the guidelines for developing and evaluating complex interventions issued by The United Kingdom Medical Research Council was applied in this thesis to address the research questions. The thesis mainly focused on the “developing intervention phase” and “testing feasibility phase”. To develop the intervention, a narrative review was conducted to overview the research progress in acupoint sensitization, which included concepts, phenomena, potential mechanisms, and clinical applications. In addition, a cross-sectional study was carried out to investigate how acupoint sensitization presented in the context of cLBP in comparison with healthy controls, and the clinical implications of the findings. In the testing feasibility phase, a randomized controlled feasibility trial was conducted to identify the uncertainties with regard to the design, methodologies, feasibility, and acceptability of a full-scale trial to compare the effectiveness and safety of sensitized-points acupuncture (Group A) with routine integrative acupuncture package (i.e. routine acupuncture + dry cupping, Group B) in the management of cLBP.
Results: The evidence in the narrative review confirmed evidence for the objective existence of acupoint sensitization, as an external manifestation of the dysfunction of internal organs. When the body is in a pathological state, disease-related acupoints become activated, and manifest in several sensitized forms, such as increased sensitivity, enlarged receptive field, and altered physical properties. Acupoint sensitization might be caused by the neurogenic inflammation associated with the modulation of neurochemicals and mediators (like 5-HT, HA, SP, TRPV-1, et al.) and dysfunction of neural activity. Therefore, stimulating sensitized acupoints is more likely to generate a favorable clinical effect compared with routine acupuncture due to the amplified response of neurons to the stimulation at sensitized acupoints. The results of the cross-sectional study suggested that pressure pain threshold (PPT) at points of interest was significantly lower in cLBP participants compared with healthy controls (P < 0.05); in addition, the receptive field was found to be larger at left BL 23 in cLBP participants (P < 0.05). By comparison, there was no statistically significant difference in skin temperature, electrical conductance, or morphology between the two groups. Reduced PPT and enlarged receptive field appeared key in defining acupoint sensitization in cLBP, and provided evidence for selecting and locating acupuncture points in future clinical studies. The findings of the feasibility study suggested that it is feasible to conduct a fully powered RCT to evaluate the effectiveness and safety of sensitized-point acupuncture compared to routine integrative acupuncture package in the management of cLBP. Thirty Participants were recruited over 10 weeks with a recruitment rate of 12 participants per month. The treatment plan in both groups was well accepted and tolerated: The treatment adherence rate was 70% in spite of the influence of COVID-19. Beyond this, the study was characterized by low adverse event rates (8.0% in Group A, 11.7% in Group B), high completion of the outcome measures (97.8% in Group A, 94.3% in Group B), and high participant retention rate (100% in Group A, 93.8% in Group B). Furthermore, preliminary analyses showed that both formats of acupuncture were potentially efficacious and safe, and sensitized-points acupuncture presented a potentially greater effect in reducing pain intensity and improving physical function of patients with cLBP, when compared with routine integrative acupuncture package.
Conclusions: The thesis provided novel and sound evidence to address the research gap concerning acupoint sensitization and its clinical features and applications in patients with cLBP. Acupoint sensitization can be characterized as basically neurogenic inflammation, which occurs at disease-related acupoints when the body is under pathological conditions. Higher pain sensitivity and an enlarged receptive field at back pain-related acupoints appeared key in defining acupoint sensitization in cLBP, and highlighted the important role of palpation in selecting and accurately locating points in acupuncture treatment. The feasibility study supported the proposal to conduct a fully powered randomized controlled trial (RCT) to investigate the comparative effectiveness and safety of sensitized-point acupuncture and routine integrative acupuncture package in the management of cLBP. Sensitized-points acupuncture presented a trend of superiority in improving pain intensity and physical function when compared with routine integrative acupuncture package. The findings of a future fully powered RCT may have positive implications in improving acupuncture clinical practice, and care of people with cLBP, and informing the development of clinical guidelines and policy decisions.