Table 3.

The GRADE “Summary of Findings” table for quality of evidence, magnitude of effect of the interventions at short- and medium to moderate-term follow-up.

Identifying methodology, population, and intervention factors associated with the analgesic effect of tDCS in Fibromyalgia. A Systematic Review, Meta-Analysis, and Meta-Regression
Patient or population: Patients with diagnosed fibromyalgia
Settings: Outpatient
Intervention: Active tDCS with or without a combined intervention
Comparison: Sham tDCS
Outcomes	Effect size	Relative and absolute effect (average % improvement (reduction) in pain (95% CIs) in relation to post-treatment score from sham group) * * Where 95%CIs do not cross the line of no effect.	No of participants (studies)	Quality of the evidence (GRADE)
Pain intensity – Short Term Effect (< 4 weeks from baseline)
Pain intensity measured using a visual analog scale or numerical rating scale	SMD 0.81 95%CI (0.43, 1.19)	This equates to a 27%, 95% CI (14% to 40%) reduction in pain intensity, on a 0 to 100 pain intensity scale	770 total. 401 on active and 369 on sham. (14 Studies)	⊕⊕◯◯ low1
Pain intensity – Moderate Term Effect (> 4 weeks from baseline)
Pain intensity measured using a visual analog scale or numerical rating scale	SMD 1.689 95%CI (0.84, 2.54)	This equates to a 57%, 95% CI (28% to 85%) reduction in pain intensity, on a 0 to 100 pain intensity scale	375 total. 193 on active and 182 on sham. (7 Studies)	⊕◯◯◯ very low2, 3, 4
GRADE Working Group grades of evidence High quality: we are very confident that the true effect lies close to that of the estimate of the effect Moderate quality: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of effect, but there is a possibility that it is substantially different Low quality: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect Very low quality: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect

¹Downgraded twice. Single randomized study (with under 300 participants) was considered inconsistent, imprecise (i.e., wide 95%CI) and with potential publication bias, providing low quality of evidence.

²Downgraded once for inconsistency due to heterogeneity.

³Downgraded once for study limitation due to high or unclear risk of bias.

⁴Downgraded once for imprecision due to small sample size

SMD: Standardized Mean Difference; CI: confidence Interval