Table 1 Quality assessment of studies of peri-conceptional folic acid supplementation (by fortification) to prevent stillbirths from neural tube defects:
Quality Assessment | Directness | Summary of findings | ||||||
|---|---|---|---|---|---|---|---|---|
No. of studies (Ref) | Design | Limitations | Consistency | Generalizability to Population of Interest | Generalizability to intervention of Interest | Events in intervention group | Events in control group | Relative Risk ( 95 % CI) |
NTDs related stillbirths: Low outcome specific quality | ||||||||
1 | Before and after study | Only one study. Total event < 50 so cannot be considered for inclusion in the LiST | Only one study | Study from Canada | Folic acid fortification study | 5 | 29 | 0.41 (0.16-1.07)a |
NTD incidence: Moderate outcome specific quality | ||||||||
11 | Before and after | Low quality population based studies | Significant heterogeneity (I2 = 88%) | All studies from high-middle income countries | Folic acid fortification studies | Â | Â | 0.59 (0.52-0.68)b |