Five studies were eligible: three RCTs, one meta-analysis and one cohort study. Results from the three RCTs (n=1,434) were reported in the review.
Of these three RCTs, two were double-blinded and one was single-blinded, one used intention-to-treat analysis, and two used a placebo control.
One study (205 patients undergoing coronary angioplasty) reported that folate was associated with a statistically significant reduction in the risk of coronary restenosis compared with placebo for patients with or without stenting: 19.6% versus 37.6% (RR 0.52, 95% CI: 0.32, 0.86, p=0.01).
The rate of restenosis was significantly lower for lesions without stent placement (101 lesions): 10.3% versus 41.9% (RR 0.25, 95% CI: 0.11, 0.57, p=0.001). There was no significant difference between folate and placebo for stented lesions: 20.6% versus 29.9% (p=0.32).
One RCT (636 patients undergoing coronary stenting) reported that folate was associated with an increase in the risk of restenosis (RR 1.30, 95% CI: 1.00, 1.69); the restenosis rate with folate was 8% higher than control (p=0.05).
One RCT (593 patients with stable CAD) reported no significant difference in the risk of vascular events between folate and placebo: 16.3% versus 19.1% (RR 0.85, 95% CI: 0.65, 2.87).