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Table 2 Summary of the findings and quality of evidence assessment using the GRADE approach

From: Effect of probiotic supplementation on gastrointestinal motility, inflammation, motor, non-motor symptoms and mental health in Parkinson’s disease: a meta-analysis of randomized controlled trials

Outcome measure

Summary of findings

Quality of evidence assessment (GRADE)

No. of patients (trials)

Effect size (95% CI)

Risk of biasa

Inconsistencyb

Indirectnessc

Imprecisiond

Publication biase

Quality of evidencef

Gastrointestinal motility

210 (8)

0.83 (0.63, 1.04)

Not serious

Not serious

Not serious

Not serious

Serious

Moderate

Stool type: Bristol Stool Scale

210 (5)

0.46 (− 0.50, 1.42)

Not serious

Serious

Not serious

Serious

Not serious

Low

Constipation symptom reduction

258 (7)

− 0.63 (− 1.72, 0.46)

Serious

Serious

Serious

Serious

Not serious

Very low

Inflammation markers

250 (4)

− 5.98 (− 9.20, − 2.75)

Not serious

Serious

Serious

Not serious

Serious

Very low

Antioxidant markers

330 (5)

0.92 (− 0.28, 2.13)

Not serious

Serious

Serious

Serious

Not Serious

Very low

Diabetes risk

240 (4)

− 3.46 (− 4.72, − 2.20)

Not serious

Serious

Serious

Not Serious

Serious

Very low

Dyslipidemia risk

240 (5)

− 1.18 (− 2.48, 0.12)

Not serious

Serious

Serious

Serious

Serious

Very low

UPDRS Part III

219 (3)

− 0.65 (− 1.11, − 0.19)

Not serious

Not serious

Not serious

Not serious

not serious

High

NMSQ

177 (2)

− 0.81 (− 1.12, − 0.51)

Not serious

Not serious

Not serious

Not serious

Not serious

High

Quality of life

509 (7)

− 1.02 (− 1.66, − 0.37)

Not serious

Serious

Not serious

Not serious

Not serious

Moderate

Anxiety Scale

366 (4)

− 0.72 (− 1.10, − 0.35)

Not serious

Serious

Not serious

Not serious

Not serious

Moderate

Depression Scale

366 (4)

− 0.70 (− 0.93, − 0.46)

Not serious

Not Serious

Not serious

Not serious

Not serious

High

Gastrointestinal motility: fermented milk

360 (3)

0.55 (0.33, 0.77)

Not serious

Not serious

Not serious

Not serious

Serious

Moderate

Gastrointestinal motility: capsules

392 (6)

1.06 (0.85, 1.28)

Not serious

Not serious

Not serious

Not serious

Serious

Moderate

  1. UPDRS, Unified Parkinson's Disease Rating Scale; NMSQ, Non-Motor Symptoms Questionnaire.
  2. aRisk of bias based on the Revised Cochrane Risk of Bias Tool for Randomized Trials (RoB2)
  3. bDowngraded if a significant and unexplained heterogeneity (I2 > 50%, P < 0.10) was not explained by meta-regression or subgroup analysis results
  4. cDowngraded if there were any factors related to the participants, interventions, or results that limited the generalizability of the results
  5. dDowngraded if the 95% confidence interval (95% CI) crossed the benefit-or-harm boundary
  6. eDowngraded if there was evidence of publication bias using Egger's test
  7. fBecause all included studies were meta-analyses of randomized clinical trials, the certainty of the evidence was graded as high for all outcomes by default and then downgraded according to prespecified criteria. Quality was graded as high, medium, low, or very low.