Epidemiology Study on Folic Acid and Orofacial Clefts

Running head: EPIDEMIOLOGY
Topic: EPIDEMIOLOGY
Name of the Student:
Name of the University:
Author Note:

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Question 1:
(a) “What study design does this study employ?”
The study design has been well explained by the author. Infants with orofacial clefts have
been treated at governmental expense in the surgical centres. Random selection of the
average of total 4000 births has been done. Controls have also been considered in the study.
(b) “What justification do the authors provide for conducting this study?”
The authors have seen that countries where fortification of foods is done, folic acid has not
been allowed have taken into consideration. The main research question has been addressed
at the highest rates of facial clefts in children in Norway. The link between folic acid
deficiency and neural tube defects lading to orofacial clefts has been found. Thus this link has
been justified by the authors through the findings of the study.
(c) “Can the same research question could be explored in Randomised Controlled trial,
explain why yes or why not?”
Randomised control trails cannot be used in this study.
Randomised control trails are usually addressed with the aspect of trials. These trials improve
endeavour of the generation of the evidence of effectiveness of health interventions. Thus for
the randomised control trials to be incorporated in this qualitative study, there should be
measures taken by the researchers considering it at the pre-trial stage along with being
explicit about the evidence based practice in experiments.
(d) “What was the overall crude and adjusted OR of cleft lip with or without cleft palate in
those consuming 400g of folic acid per day compared to no consumption of folic acid.
The folic acid supplementation during pregnancy has been associated with reduced risk of

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isolated left lip or without cleft palate after multivitamin adjustment. The odds ratio or OR
have been 0.61. The confidence interval has been considered to be 95% from an interval of
0.39 to 0.96.
(e) “How would you interpret the finding in 4 (d)?”
Odds ratio is a measure of comparison which compares the odds of occurrence of diseases
along with those who have been exposed to the disease than those who have not been
exposed. Thus form the given calculation of the odds ratio the presence of association of
cleft along with the deficiency of the folic acid measured by 400 g supplement has been
calculated.
(f) “The authors state that the controls in this study are population-based controls - are they?
Why or why not?”
Population based controls are those where vases usually come from a defined population and
a fixed geographical area and controls are sampled mainly form the same population. This
study is population based as only the infants born in the time period of 1996 to 2001 among
only the residents of Norway have been considered. Thus the population has been fixed to a
time period and only the state of Norway has been chosen.
(g) “What could be source of measurement bias in this study and did the authors tried to
alleviate this problem. Explain with evidence from the text.”
There has been source of measurement bias as the errors in the analysis have occurred
randomly without favouring a bias. Evidence from the text is “We cannot reconstruct the

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mothers′ complete exposure history retrospectively, but the collection of brands, bottles, and
labels allowed us to correct some errors in self-report.”
Facial cleft lip ( with or without cleft
palate)
Control
Smokers 42 55
Non smokers 72 190
Question 2
“In another case –control study researchers investigated cleft lip with or without cleft palate
by smoking status in those participants who reported consuming folic acid supplements. In
this sub-group there were 42 cases of cleft lip with or without cleft palate and 55 controls
who were current smokers; and there were 72 cases of cleft lip with or without cleft palate
and 190 controls who were non-smokers.”
(a) “Construct a 2x2 table with columns and rows headings and calculate an appropriate
measure of the strength of association between smoking and cleft lip with or without cleft
palate in those who consumed folic acid supplements during pregnancy.”
The strength of association from the given data relating to the presence of facial clefts among
smokers or non-smokers has been listed in the above table.
b) “Interpret the findings in (a) in your own words.”
From the above table the strength of association between the variables can be determined.
Here the probability of having an oral cleft have smokers and non-smokers has been