Generalized linear model analysis to assess the relationship of the descending pain modulatory system function according to responders (n = 20) and non-responders (n = 13) to the conditioned pain modulation test (CPM-test) on the clinical symptoms and left S1-PAG rs-FC (n = 33)
Outcome: Left S1-PAG rs-FC | B | SE | 95% CI | Wald χ2 | df | Effect size | |
---|---|---|---|---|---|---|---|
(Intercept) | 0.335 | 0.1816 | (–0.021 to 0.690) | 3.394 | 1 | 0.065 | |
Responders to CPM-test | 0.145 | 0.0457 | (0.056 to 0.240) | 10.109 | 1 | 0.001 | 0.58 |
Non-responders to CPM-test | reference | ||||||
Pittsburgh Sleep Quality Index | –0.014 | 0.0058 | (–0.026 to –0.003) | 6.162 | 1 | 0.013 | 0.45 |
Fibromyalgia Impact Questionnaire | –0.002 | 0.0010 | (–0.004 to 0.001) | 4.417 | 1 | 0.036 | 0.38 |
Pain severity on Numerical Pain Scale (0–10) | –0.011 | 0.0052 | (–0.021 to 0.001) | 4.395 | 1 | 0.036 | 0.38 |
Central Sensitization Inventory | 0.003 | 0.0012 | (0.001 to 0.005) | 5.737 | 1 | 0.017 | 0.44 |
Primary outcome – generalized linear model analysis to compare responders and non-responders.
The Cramerʼs V was used as a measure of effect size for chi-square tests. The size effect was interpreted as follows: Standards for interpreting Cramerʼs V proposed by Cohen (1988) are the following. DF (degrees of freedom) = 1 (0.10 = small effect) (0.30 = medium effect) (0.50 = large effect). https://www.campbellcollaboration.org/escalc/html/EffectSizeCalculator-R5.php.
CPM-test: conditioned pain modulation test, rs-FC: resting-state functional connectivity, S1: primary somatosensory cortex, PAG: periaqueductal gray, B: regression coefficient, SE: standard error, CI: confidence interval, χ2: Wald chi-square, df: degrees of freedom.