. 2021 Apr 7;9:e11173. doi: 10.7717/peerj.11173

Table 3. Summary of findings including GRADE quality assessment for comparison between olive leaf extract and placebo or no treatment.

		No. of participants		Anticipated absolute effects ^*
Outcomes	No. of participants (studies)	Placebo or no treatment	Olive leaf extract 500 mg per day dosage	MD	95% CI	P-value	Certainty of the evidence (GRADE)	Comments
Systolic blood pressure (mmHg)	80 (2 RCTs)	40	40	5.78 lower	−10.27 to -1.3, I²= 0%	0.01	⊕⊕ $○$ $○$ LOW^a	Risk of bias: not serious Inconsistency: serious^a; indirectness: not serious; imprecision: serious^a;
Diastolic blood pressure (mmHg)	80 (2 RCTs)	40	40	1.69 lower	−5.73 to 2.34, I²= 0%	0.41	⊕⊕ $○$ $○$ LOW^a^,^b	Risk of bias: not serious Inconsistency: serious^a^,^b; indirectness: not serious; imprecision: serious^a;
Total cholesterol (mg/dl)	80 (2 RCTs)	40	40	4.97 lower	−17.28 to 7.34, I²= 81%	0.43	⊕⊕ $○$ $○$ LOW^a^,^b	Risk of bias: not serious Inconsistency: serious^a^,^b; indirectness: not serious; imprecision: serious^a;
LDL (mg/dl)	80 (2 RCTs)	40	40	0.29 higher	−0.2 to 0.79, I²= 0%	0.25	⊕⊕ $○$ $○$ LOW^a^,^b	Risk of bias: not serious Inconsistency: serious^a^,^b; indirectness: not serious; imprecision: serious^a;
HDL (mg/dl)	80 (2 RCTs)	40	40	0.98 higher	−1.63 to 3.6, I²= 78%	0.46	⊕⊕ $○$ $○$ LOW^a^,^b	Risk of bias: not serious Inconsistency: serious^a^,^b; indirectness: not serious; imprecision: serious^a;
Fasting blood glucose (mmol/l)	60 (1 RCT)	30	30	0.08 higher	−0.25 to 0.4	0.65	⊕⊕ $○$ $○$ LOW^a	Risk of bias: not serious Inconsistency: serious^a; indirectness: not serious; imprecision: serious^a;
HOMA-IR	60 (1 RCT)	30	30	0.17 higher	−0.17 to 0.51	0.33	⊕⊕ $○$ $○$ LOW^a	Risk of bias: not serious Inconsistency: serious^a; indirectness: not serious; imprecision: serious^a;
Insulin (µu/ml)	60 (1 RCT)	30	30	0.61 higher	−0.84 to 2.06	0.41	⊕⊕ $○$ $○$ LOW^a	Risk of bias: not serious Inconsistency: serious^a; indirectness: not serious; imprecision: serious^a;
creatinine (mg/dl)	60 (1 RCT)	30	30	0.09 higher	−0.18 to 0.36	0.52	⊕⊕ $○$ $○$ LOW^a	Risk of bias: not serious Inconsistency: serious^a; indirectness: not serious; imprecision: serious^a;
ALT (U/L)	60 (1 RCT)	30	30	0.3 higher	−2.26 to 2.86	0.82	⊕⊕ $○$ $○$ LOW^a	Risk of bias: not serious Inconsistency: serious^a; indirectness: not serious; imprecision: serious^a;
AST (U/L)	60 (1 RCT)	30	30	0.57 higher	−2 to 3.14	0.66	⊕⊕ $○$ $○$ LOW^a	Risk of bias: not serious Inconsistency: serious^a; indirectness: not serious; imprecision: serious^a;
IL-6 (ng/L)	60 (1 RCT)	30	30	6.83 lower	−13.15 to −0.51	0.03	⊕⊕ $○$ $○$ LOW^a	Risk of bias: not serious Inconsistency: serious^a; indirectness: not serious; imprecision: serious^a;
IL-8 (ng/L)	60 (1 RCT)	30	30	8.24 lower	−16 to -0.48	0.04	⊕⊕ $○$ $○$ LOW^a	Risk of bias: not serious Inconsistency: serious^a; indirectness: not serious; imprecision: serious^a;
TNF-alpha (ng/L)	60 (1 RCT)	30	30	7.4 lower	−13.23 to -1.57	0.01	⊕⊕ $○$ $○$ LOW^a	Risk of bias: not serious Inconsistency: serious^a; indirectness: not serious; imprecision: serious^a;

Notes.

The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: Confidence interval; MD: Mean difference.

Explanations

small population.

wide CI.

GRADE Working Group grades of evidence

High certainty: We are very confident that the true effect lies close to that of the estimate of the effect

Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different

Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect

Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect