Problem 2: Maternal Drug Consumption and Birth Defects As an epidemiologist, you

Question

Problem 2: Maternal Drug Consumption and Birth Defects As an epidemiologist, you have investigated the effect of a drug suspected of causing malformations in newborn infants when the. drug.in.questionis.takenby. pregnant women during the course of their pregnancies. As your sample, you have used the last 250 single births occurring in a given hospital. After each birth a medication history was taken from the new mother and from her doctor. In addition, you have reviewed medical records to verify use of the drug during pregnancy. You have thus built a paperlelectronic trail following these mothers during the entire course of their pregnancies, constructing a complete and accurate record of drug use during pregnancy. The resultant data are: Fifty mothers have taken the suspected drug during their pregnancies. Of these mothers, 42 have delivered malformed infants. In addition, there were 15 other infants born with malfunctions. 1) What about the way this study was conducted tells you that it is the study design that it is? 2) Draw a 2 by 2 table, with all totals (including marginal) for this study 3) From the 2 by 2 table that you drew, calculate the most appropriate measure of association. Show all steps 4) In one sentence precisely interpret the measure of association that you calculated, according to the style presented in the notes.

Explanation / Answer

1)

The study conducted is to check the relationship between the drug during pregancy and malformed infants delivery.

Is the drug inflencing the malformed infant delivery.

Given

2)

Totally 50 have taken drugs, malformed were 48. Therefore normal infants for mothers who have taken medical drugs are 8 .

malformed infants row total is 42+15 i.e.57

normal infant row total is 250-57 i.e.193

Taken drugs and normal infants = 50-42 = 8

no drugs and normal infants = 193-8 = 185

3)

degrees of freedom = (row -1)* (col-1) =(2-1)*(2-1) = 1

find the expected values of the table

(row total for that value * column total for that value)/ grand total

chi square = sigma ( [obs(r,c) - exp(r,c) ]^2/ exp(r,c) )

chi square = 132.99

Probability (chi sq >132.99 for 1 degree of freedom ) is p-value

from the chi square table, we find that the p-value is less than 0.0001

4)

Null hypothesis was H0: no relation between malformed infants and medical drugs. Both drugs and no drug treatments are same.

Alternate hypothesis was H1: there is relation between malformed infants and medical drugs. Drug treatment and no drug treatment are different.

Since p-value is less than 0.05, reject null hypothesis.

Conclusion: There is relation between medical drugs and malinformed infants. Drug treament results in malformed infants.

there was relat

taken drug no drug Row Total malformed infants 42 15 normal infants Column Total 50 250

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