Cross-sectional and longitudinal analysis of conditioned pain modulation and pain in fibromyalgia: CPM as an effect modifier of pain changes over time.
Luis Castelo-Branco, Kevin Pacheco-Barrios, Alejandra Cardenas-Rojas and 8 others
PMID 39055778WHAT IT FOUND
Fibromyalgia patients with poor baseline pain inhibition showed greater improvement in pain and function over time than those with strong inhibition.
However, this was a small, exploratory secondary analysis of an ongoing trial, so these findings are hypothesis-generating and not yet clinically actionable.
Key findings
01Baseline conditioned pain modulation (CPM) efficiency did not correlate with current pain intensity, depression, or anxiety scores.
02Patients classified as having low-efficiency CPM at baseline demonstrated a significantly greater decrease in pain and improvement in quality of life over the study period compared to those with high-efficiency CPM.
03The study was an exploratory secondary analysis of an ongoing randomized trial where treatment assignments remained blinded, limiting the ability to attribute changes to specific interventions.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
The sample size was very small (41 patients), and the study was explicitly exploratory and hypothesis-generating. The data came from an ongoing randomized trial where treatment assignments were blinded, so it is impossible to know if the observed changes were due to the specific interventions (tDCS/exercise) or natural history/placebo effects. No corrections for multiple comparisons were made, increasing the risk of false-positive findings. Severely depressed patients were excluded, limiting generalizability to the broader fibromyalgia population. Dropout rates were significant, with only 24 of 41 subjects completing all visits.
Declared interests
The authors state no conflicts of interest.
The easy way to misread this
Do not interpret the greater improvement in pain and function for patients with low-efficiency CPM as evidence that this specific subgroup responds better to treatment. The study was a blinded secondary analysis of an ongoing trial, meaning the treatment groups were unknown, so these differences cannot be attributed to the interventions delivered.