Page 79 - JCBP-2-3

Journal of Clinical and
Basic Psychosomatics HD-tDCS on pain in SSD-P

Table 3. Frequency and types of side effects experienced after active versus sham stimulation
Side effects checklist Active stimulation (N=30) Sham stimulation (N=30) Chi‑square value (P‑value)
Itching at the stimulation site 9 (30.0%) 6 (20.0%) 0.813 (0.371)
Burning at the stimulation site 25 (83.3%) 12 (40.0%) 11.915 (<0.01)*
Pain at the stimulation site 16 (53.3%) 7 (23.3%) 5.711 (0.016)*
Note: The results are expressed as frequency (%); *P<0.05.

Table 4. Outcome of pain on the NRS of Group A (active first followed by sham) and Group B (sham first followed by active)
Group Mean (SD) Repeated T0 versus T2 T0 versus T1 T1 versus T2
measures ANOVA
T0 T1 T2 P Mean P Mean difference P Mean difference P
difference (SE) (SE) (SE)
A (n=16) 7.50 (1.97) 4.18 (2.29) 4.18 (2.29) <0.01* 3.313 (0.405) <0.01* 3.313 (0.405) <0.01* 0 (0) -
B (n=14) 8.42 (1.65) 7.92 (2.02) 6.21 (2.22) <0.01* 2.214 (0.334) <0.01* 0.500 (0.292) 0.331 1.714 (0.194) <0.01*
Notes: *P<0.05; T0, T1, and T2 represent the times of measurements at baseline, week 1, and week 2, respectively.
Abbreviations: η : Partial eta-squared; MD: Mean difference; NRS: Numerical rating scale; N: Total number; p: P-value; SD: Standard deviation;
2
p
SE: Standard error; T0: Baseline value; T1: Week 1 value; T2: Week 2 value; ANOVA: Analysis of variance.
only. The same pattern was observed for all other outcome A crossover study design was employed, which is
measures on repeated measures ANOVA. recommended and commonly utilized in trials on pain
treatment and is known to reduce between-patient
The outcome at T2 was comparable in groups A and B, 28
owing to the persistence of changes in Group A patients. variability. Moreover, permuted block randomization was
conducted to rule out any potential bias due to the order
This finding indicates that the intervention caused benefits of active or sham stimulation. In addition, a one-way
29
that persisted for at least 1 week following active HD-tDCS ANCOVA with order as a covariate showed no interaction
administration.
of order and group. Blinding was ensured, as patients were
Notably, we could not find any differential effect of unable to discern above chance (P = 0.20) whether they
gender on changes in scores across different time points. had received active or sham stimulation. The ramp-up
and ramp-down at the beginning and end, respectively, of
3.5. Global improvement sham stimulation simulate active stimulation, making the
30
Clinician-rated global improvement on the CGI-Efficacy patient perceive the sensation of current flowing. There
Index at T1 showed a statistically significant difference was no statistically significant difference between patients
between active and sham stimulation but no statistically blinded to the active and sham groups at entry on any of
significant difference at T2. Similarly, patient-rated the sociodemographic or clinical parameters, eliminating
global improvement on PGIC at T1 showed a statistically any possible confounder bias between the groups at their
significant difference between active and sham stimulation entry into the study. 29
but no statistically significant difference at T2. Differences between the groups as per entry status at
T0 versus T1 in the first active group and T1 versus T2
4. Discussion in the first sham group show that only active intervention

To our knowledge, this study is one of the first studies had any impact on reducing pain scores when given first
investigating the effects of HD-tDCS on pain in SSD-P. or second, irrespective of order. Sham stimulation given
Patients were on a stable dose of pharmacological treatment either as the first or second session showed no significant
for at least 3 months before recruitment for HD-tDCS as differences in the outcome parameters. This finding could
an add-on therapy. Although our primary focus was on also indicate that in the group receiving active stimulation,
the effect on pain, a host of secondary outcomes such as there was no carryover effect when sham stimulation was
interference due to pain, burden due to somatic symptoms, provided.
depressive symptoms, anxiety symptoms, disability due Apart from the use of HD-tDCS, focal stimulation
to pain, and cognitive features was also assessed using was also ensured by single-pulse transcranial magnetic
standard rating scales, providing a holistic approach to stimulation-aided marking of the left motor cortex. When
pain. two within-session repeated HD-tDCS administrations

Volume 2 Issue 3 (2024) 6 doi: 10.36922/jcbp.2002