Your colleagues conducted a cohort study to examine the association between alcohol consumption and heart disease. The risk ratio obtained was 9.2, when comparing those reporting high levels of alcohol consumption with those reporting abstinence or low levels of alcohol consumption.
Consider the following four points and comment on their relevance (if any) to the study conclusions and the determination of causality.
a) The rate ratio of 9.2 indicates a strong association, which lends support for causality
b) Strong confounding may actually be causing the strong association seen
c) Other studies of the same exposure-outcome association reported risk ratios in the range of 2.5- 4.0
d) The temporal sequence of the exposure and outcome should be known in order to draw accurate conclusions