Figure 1.
Systematic Review Process Flowchart.
Table 1.
Studies Conducted with Healthy Subjects.
Table 2.
Studies Conducted with Patients.
Table 3.
Overall Study Outcome.
Table 4.
Quality Assessment.
Figure 2.
Results of the risk of bias assessment as depicted in table 4 are summarized. Percentages of studies with ‘low risk of bias’, ‘high risk of bias’, or ‘unclear risk of bias’ are illustrated for each item of the Cochrane Collaboration's tool.
Figure 3.
Considering the previously defined quality criteria (see methods) as well clinical homogeneity according to the investigators accordance, five studies on the effect of acupuncture on the PPT conducted with patients were combined in two meta-analyses. The short-term effect on the PPT directly after a series of acupuncture sessions as assessed in four studies (A) was found to be significant but small. Two studies were analyzed regarding long-term effects of acupuncture on the PPT (B) which was also found to be significant but small. Heterogeneity was found to be substantial in both analyses.