A study of utilizing ten years of birth certificate data for New Jersey (approximately 115,000 births/year) showed that pregnancies where women resided in high air pollution areas had 1.1 times the risk of having a pregnancy less than 37 weeks of gestation compared to women residing in lower air pollution areas. The final results were RR=1.1 (95% CI 1.08 – 1.2).
a. Is this result considered statistically significant? How do you know that it is or is not?
b. Do you think these results are clinically significant? How would you evaluate this further to understand the importance of the results?
The results of a 10-year cohort study of obesity and diabetes are shown in the table below:
At beginning of study
Diabetes Developed
Diabetes Did Not Develop
3000 obese people
98
2902
6000 not obese people
30
5970
a. What is the risk ratio for obesity and development of diabetes?
b. What is the cumulative incidence (risk) of diabetes in the obese people that can be associated with obesity?
c. In the general population, 25% of the population is obese. If we apply the results of the study above to the general population, what is the proportion of diabetes in the population that is associated with obesity?
Having certain kinds of congenital heart conditions (e.g. certain heart murmurs) increases the risk of having endocarditis (a heart infection). The risk of having endocarditis is 1/100,000 in 10 years among those without the heart murmur and 3/100,000 in 10 years for those with the heart murmur.
a. Show and discuss the distinction between the ABSOLUTE effect and the RELATIVE effect of having the heart murmur on the risk of endocarditis.
b. What measures would you use and how would you interpret them?
