We are just about to start an assessment of effects of food fortification with folic acid on the incidence of neural tube defects. There are no RCTs in this field (besides those few that looked at supplementation). However, there are a number of reports from registries and official statistics that report on trends over time(before-and-after comparisons). I have found very few articles that specifically discuss what to consider when assessing the quality of these reports (and reports based on time series data). Suggestions are welcome!
Bengt Brorsson
SBU
Sweden
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