Effect of Curcumin on Diabetic Kidney Disease: A Systematic Review and Meta-Analysis of Randomized, Double-Blind, Placebo-Controlled Clinical Trials

Table 4

The certainty of the evidence for the effects of curcumin supplementation on outcomes based on the GRADE assessment.

Outcomes	No. of trials	Study design	Quality assessment					Effect of WMD (95% CIs)	Quality
			Risk of bias	Inconsistency	Indirectness	Imprecision	Publication bias
Renal function
SCr	4	RCTs	Serious^a	Not serious	Not serious	Not serious	Not serious	−0.16 (−0.30, −0.02)	⨁⨁⨁◯ moderate
BUN	2	RCTs	Serious^a	Not serious^b	Not serious	Serious^c	Not serious	1.10 (−1.72, 3.92)	⨁⨁◯◯ low
PRO	4	RCTs	Serious^a	Not serious^d	Not serious	Serious^c	Not serious	−0.09 (−0.73, 0.92)	⨁⨁◯◯ low
Lipid profile
TC	4	RCTs	Serious^a	Not serious	Not serious	Not serious	Not serious	−10.13 (−17.84, −2.41)	⨁⨁⨁◯ moderate
TG	4	RCTs	Serious^a	Not serious	Not serious	Serious^c	Not serious	3.42 (−6.39, 13.22)	⨁⨁◯◯ low
HDL-C	3	RCTs	Serious^a	Not serious	Not serious	Serious^c	Not serious	1.16 (−1.55, 3.87)	⨁⨁◯◯ low
LDL-C	3	RCTs	Serious^a	Serious^e	Not serious	Serious^c	Not serious	−1.06 (−17.89,15.77)	⨁◯◯◯ very low
Blood pressure
SBP	4	RCTs	Serious^a	Not serious	Not serious	Not serious	Not serious	3.94 (1.87, 6.01)	⨁⨁⨁◯ moderate
DBP	4	RCTs	Serious^a	Not serious^f	Not serious	Serious^c	Not serious	0.21 (−5.64, 6.05)	⨁⨁◯◯ low
Glycemic control
FBG	4	RCTs	Serious^a	Not serious	Not serious	Not serious	Not serious	−8.29 (−15.19, −1.39)	⨁⨁⨁◯ moderate

SCr, serum creatinine; BUN, blood urea nitrogen; PRO, proteinuria; TC, total cholesterol; TG, triglycerides; LDL-C, low-density lipoprotein-cholesterol; HDL-C, high-density lipoprotein-cholesterol; SBP, systolic blood pressure; DBP, diastolic blood pressure; FBG, fasting blood glucose; WMD, weight mean difference; CI, confidence interval; RCT, randomized controlled trial. ^aFor risk of bias, the majority of included studies were considered to be at high risk of bias due to the fact that outcomes assessment was not blinded, so it was downgraded. ^bAlthough there was substantial heterogeneity for the effect of curcumin on BUN, it was explained when the study conducted by Shafabakhsh et al. was removed according to the sensitivity analysis (original:  = 60%, heterogeneity = 0.082; after study was removed:  = 0%, heterogeneity = 0.601). ^cThe 95% CIs for effect estimates overlap the zero. ^dAlthough there was considerable heterogeneity for the effect of curcumin on PRO, it was associated with mean age (≤60 years,  = 41.4%), curcumin intake (≥1500 mg/day,  = 47.4%), and follow-up period (＞2 months,  = 47.4%). ^eThere was substantial heterogeneity ( ≥ 77.2%, < 0.1) that was unexplained by any subgroup or sensitivity analysis for the effect of curcumin on LDL-C. ^fAlthough there was substantial heterogeneity, it was explained for the effect of curcumin on DBP with follow-up periods (＞2 months,  = 21.4%).