Exercise: Readmission to hospital for asthmatic children using Stata 9

The data set readmit.dta gives part of the data from a study of 1034 New Zealand children who had been discharged from hospital following an admission for asthma (Mitchell et al., 1994). The authors wanted to find what factors predicted discharge. In particular, some of the children had been discharged with a written crisis plan, to help their parents deal with any subsequent exacerbations of asthma. Would this help to reduce the risk of admission?

Load the data set readmit.dta and start Stata.

Questions

1. How many children are there and how many were readmitted?

Check suggested answer 1.

2. Draw a survival curve for time to readmission to hospital.

Check suggested answer 2.

3. Plot the survival for children discharged with and without a crisis plan and test the null hypothesis that readmission is unrelated to the presence of a crisis plan.

Check suggested answer 3.

4. Is the presence of a crisis plan related to other variables which might increase the risk of readmission, such as age, sex, number of previous admissions, pulse rate, or respiration rate?

How do children given a crisis plan differ from the other children?

Check suggested answer 4.

5. Which two of these predictor variables would you expect to be related to one another, whatever the disease in question?

Check suggested answer 5.

6. What is the best estimate of the effect of the crisis plan? Give a confidence interval for the estimate. How do the other variables predict readmission?

Check suggested answer 6.

7. Does the adjustment for possible confounding variables change the estimate of the effect on readmission of the crisis plan?

Check suggested answer 7.

8. Can we conclude giving a family a crisis plan increases the child's chance of being readmitted?

Check suggested answer 8.

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Last updated: 6 February, 2008.