Between 1993 and 1995, investigators enrolled 1,000 pregnant women who worked outside the home and were seen at an obstetric clinic in New York City into a cohort study.
Between 1993 and 1995, investigators enrolled 1,000 pregnant women who worked outside the home and were seen at an obstetric clinic in New York City into a cohort study. Women currently experiencing depressive symptoms were ineligible for recruitment into the study. The study aim was to examine the association between how soon women returned to work following the birth of their child and post-partum depressive symptoms. Data on demographic, health status, and health behavior variables were collected at baseline.
Women were contacted 12 weeks post-partum to assess whether they were newly experiencing depressive symptoms and the amount of time they took to return to work. A total of 919 women were available for follow-up and were thus included in the analysis. The following data were obtained:
Depressive Symptoms
Return to Work
Yes
No
Total
< 5 weeks
172
395
567
> 5 weeks
60
292
352
Total
232
687
919
1. Calculate and interpret the appropriate measure of association. The 95% confidence interval of this association was: (1.37, 2.31).
The investigators were concerned that household income level (assessed at baseline) might be influencing the observed association between when women returned to work following the birth of their child and post-partum depressive symptoms.
2. Draw a causal diagram to show the possible relationships between household income, return to work, and post-partum depressive symptoms.
The investigators stratified the data by household income level as follows:
Lower Income
Depressive Symptoms
Higher Income
Depressive Symptoms
Return to Work
Yes
No
Subtotals
Yes
No
Subtotals
Total
<5 weeks
160
295
455
12
100
112
567
> 5 weeks
50
164
214
10
128
138
352
Total
210 459 669 22 228 250 919
3. Since a confounder must be associated with the outcome and exposure, calculate an odds ratio to evaluate the association between income level (3rd variable) and amount of time before returning to work (exposure). Interpret this odds ratio.
Income
Returning to work
<5 weeks
>5 weeks
TOTAL
Lower
(160+295)
455
(50+164)
214
669
Higher
(12+100)
112
(10+128)
138
250
TOTAL
567 352
919
4. Now evaluate whether income level is associated with incident post-partum depressive symptoms among those who returned to work >5 weeks using the appropriate measure of association.
Evaluating the association between income level and post-partum depressive symptoms among the non-exposed (returning to work ≥ 5 weeks):
Depressive Symptoms
Income Yes No
Total
Lower
50
164
214
Higher
10
128
138
Total
60 292
352
5. The next step is to look at the stratum specific risk ratios.
Calculate the risk ratios for the association between returning to work and post-partum depressive symptoms in those with high income and those with low income. How do they compare?
The 95% confidence interval for the risk ratio calculated in question 5 among lower income women was 1.15-1.98. Among higher income women, the 95% confidence interval was 0.663-3.30. What conclusions can you draw with this additional information?
6. Using information from the previous questions, determine whether income confounds the observed association between when women returned to work following the birth of their child and post-partum depressive symptoms. In your answer, comment on the: a) criteria a variable must meet to be considered a confounder; b) the stratum-specific risk ratios; and c) the magnitude (expressed as a percent) of the difference between the crude and the stratum-specific risk ratios.
7. Might there still be residual confounding by income even after controlling for high and low income? Why? How could you improve control for income?
8. Can you think of other factors that might explain the observed association between returning to work and post-partum depression?
9. If women who returned to work in less than five weeks after giving birth were less likely to maintain breast feeding and breast feeding is known to impact post-partum symptoms, is breast feeding a likely confounder between time to returning to work and post-partum depression? draw a diagram!
Collepals.com Plagiarism Free Papers
Are you looking for custom essay writing service or even dissertation writing services? Just request for our write my paper service, and we'll match you with the best essay writer in your subject! With an exceptional team of professional academic experts in a wide range of subjects, we can guarantee you an unrivaled quality of custom-written papers.
Get ZERO PLAGIARISM, HUMAN WRITTEN ESSAYS
Why Hire Collepals.com writers to do your paper?
Quality- We are experienced and have access to ample research materials.
We write plagiarism Free Content
Confidential- We never share or sell your personal information to third parties.
Support-Chat with us today! We are always waiting to answer all your questions.
