Table 2

GRADE Evidence profile: physical functioning outcomes as per Oswestry Disability Index (ODI) for patients with chronic pain following spinal cord stimulation

Outcome	Limitations	Inconsistency/heterogeneity	Indirectness	Imprecision	Publication bias	Mean difference or OR (95% CI)	No of studies	Certainty of evidence (GRADE)
3 month ODI Scores	High risk of bias*	High I² statistic. Clinical heterogeneity present	Not serious	Not serious	Strongly suspected†	−19.90 (−28.24 to 11.57)	12 Studies (eight observational studies, 4 RCT)	⊕〇〇〇 Very low
6 month ODI Scores	High risk of bias*	High I² statistic. Clinical heterogeneity present	Not serious	Not serious	Strongly suspected†	−11.20 (−14.85 to 7.55)	15 Studies (10 observational studies, 5 RCT)	⊕〇〇〇 Very low
12 month ODI Scores	High risk of bias*	High I² statistic. Clinical heterogeneity present	Not serious	Not serious	Strongly suspected†	−17.00 (−23.07 to 10.94)	17 Studies (14 observational studies, 3 RCT)	⊕〇〇〇 Very low
24 month ODI Scores	High risk of bias*	High I² statistic. Clinical heterogeneity present	Not serious	Not serious	Strongly suspected†	−17.11 (−20.88 to 13.34)	Three observational studies	⊕〇〇〇 Very low

‘⊕〇〇〇’” reports on level of certainty. The ‘⊕’ means one positive point was given out of four total possible points.
*Most of the observational studies had a high risk of bias in the NOS categories of ‘selection’, ‘comparability of cohorts’, and ‘assessment of outcome’. The RCTs had high risk of bias due to the lack of blinding of participants, personnel, or outcomes.
†Based on Funnel plot and Egger’s test, presence of small sample size studies.
GRADE, Grading of Recommendation, Assessment, Development, and Evaluation; NOS, Newcastle-Ottawa scale; ODI, Oswestry Disability Index; RCTs, randomised controlled trials.