WEEK3: Population interventions: folate flour story Flashcards
In 1954, there was a double blind randomised control trial of folate treatment. Tell me about it:
- In 1954, double blind randomised controlled trial of folate treatment
- before conception to prevent recurrence of NTDs was conducted in 111 women out of 905.
- Results showed a non significant P value (due to small sample size).
- Intention to treat analysis was used and all the NTDs in folate group were in non compliers.
What was the ethical controversy in the trial in 1983?
- planned MRC randomised trial
- aimed to get over 2000 subjects
- only got 132 patients
- Shows how non randomised trials can ruin the prospects for randomised.
What is relative risk?
EVENT OCCURING IN GROUP A/ EVENT OCCURING IN GROUP B
- Relative risk is the number that tells you how much something you do, such as maintaining a healthy weight, can change your risk compared to your risk if you’re very overweight.
Observation studies of the use of vitamins containing folic acid and the occurrence of NTDs in the general population were concluded AND ALL HAD RR below 1. What does this conclude?
- folic acid acts as a protective factor, with confidence intervals excluding the value 1.
What does Relative Risk = 1 mean?
- the risk of the bad group and the risk of the modified group are the same
An MRC randomised trial took place with 4 groups (only folate, only vitamins, folate and vitamins, nothing). The relative risk was 0.28. What does this mean?
- 73% reduction in NTD with confidence intervals without the value 1.
What did the department of health state in 1991?
- should take folic acid before conception
“The main finding was that folic acid supplements, taken by women who had already experienced one or more pregnancies affected by neural-tube- defects, reduced the risk by 72%
In such women “ it is essential to commence supplementation before conception occurs”
“Whether it is desirable to extend folic acid supplements to all women of reproductive age or to those intending to become pregnant is an entirely different issue. We are therefore setting up an expert advisory committee…”
There was an RCT on prevention of first occurence of NTD’s. How were the P values here?
- Another RCT was conducted on the prevention of the first occurrence of NTDs by use of periconceptual vitamin supplementation in around 5000 pregnancies.
- This trail had a significant P value to reduce NTDs.
What did the department of health say after this RCT?
“For the prevention of first occurrence of neural tube defect, the Expert Group report recommends that all women planning a pregnancy take a dietary supplement of 0.4 milligrams of folic acid / day”
What happened to the levels of folate being consumed in the population?
- Epidemiology showed that until folate (OTC/prescription) was given, NTDs dropping
- if stopped, then flattened.
- maybe bc folic acid was taken by health conscious people and not people at high risk
e. g. lower socioeconomic groups did not take them as much
What population strategy was put in place?
Evidence of efficacy of folic acid conclusive
- Supplement needed for a reasonable protective effect = 0.4mg/day.
- This is twice the current average intake.
- Without screening 1500 affected children would be born in Britain each year. >1000 preventable
What are the problems with targetting women?
Problem with targeting women planning pregnancies are:
- most not aware of the problem - highest risk groups least likely to take supplements - many pregnancies are not planned
What did the department of health think to do to protect the population?
- put folic acid in flour
- similar to immunisation
- benefits the minority
What is the problem with putting folic acid in flour?
- Requires legislation.
- White flour compulsorily fortified with niacin, thiamine, calcium, iron
What do folic acid supplements do?
- reduce levels of homocysteine
- homocysteine is a non causal factor for CHD
