Objectives: To optimally select chronic pain patients for different treatments, as it is of interest to identify patient characteristics that might moderate treatment effect. Our aim was to evaluate the impact of possible moderators on the effect of acupuncture treatment using a large data set.
Methods: We used data from an individual patient data meta-analysis of high-quality randomized trials of acupuncture for chronic headache and migraine, osteoarthritis, and back, neck, and shoulder pain. Using meta-analytic trial-level and patient-level regression analyses, we explored the impact of 5 documented patient characteristics (patients' age at baseline, sex, pain duration, baseline pain severity and baseline psychological distress) on the effect of acupuncture.
Results: A total of 39 trials met the inclusion criteria: 25 use sham-acupuncture controls (n = 7097) and 25 non-acupuncture controls (n = 16,041). Of the 5 patient characteristics analyzed, only baseline pain severity was found to potentially moderate the treatment effect of acupuncture, with patients reporting more severe pain at baseline experiencing more benefit from acupuncture compared to either sham-control or non-acupuncture control. Baseline psychological distress showed small treatment moderating effects, and results for sex were inconsistent. There was no strong evidence that age or duration of pain influenced the response to acupuncture.
Discussion: Of 5 patient characteristics tested, we found only baseline severity of pain to potentially moderate the effect of acupuncture treatment. For clinical practice, the evidence from this analysis does not justify stratifying chronic pain patients into subgroups that should or should not receive acupuncture on the basis of these 5 characteristics. Future acupuncture trials should assess other potentially important effect moderators.