In a hypothetical study, 3,000 smokers and 5,000 nonsmokers were recruited. The objective of the study was to establish the relationship of smoking and coronary heart disease (CHD). Both groups were found to be free of heart disease at baseline. They were then followed up for the development of CHD. At the end of the study, CHD was found to be 84 among the smokers and 87 among the nonsmokers.
a) What is the kind of this study design?
b) Estimate the relative risk of CHD associated with smoking?
c) Calculate the attributable risk (%) for CHD in smokers and interpret your results?