Commentary: Incubation of coronary heart disease—recent developments

Over 20 years ago Geoffrey Rose, using data from the Seven Countries' study,1 reported that ecological correlations between cholesterol levels (and to a lesser extent blood pressure) and coronary heart disease (CHD) mortality were stronger for cholesterol measured many years before mortality was assessed, than if contemporaneous cholesterol measures and CHD mortality were correlated. Commenting for a tobacco company soon after publication, Peter Lee, criticized the analyses, and dismissed the evidence Rose used to propose that CHD has at least a 10 year incubation time as being 'so weak as not to be worth publishing'.2 Rose, however, was aware of many of the weaknesses, and, anticipating Lee's final comment, advised that individual-level comparison of long-term and short-term predictive power should be undertaken. Three main hypotheses flow from Rose's conclusions. First, CHD is set in train long before it manifests clinically; second, measuring risk factors earlier in life provides a better measure of risk than relying on later measures; and third, at any level of CHD risk factors in late adulthood, those who have not been exposed in early years will have lower risk of CHD. Although he highlighted several statistical weaknesses, Lee himself was not wholly dismissive of the paper, accepting that 'some or all of the conclusions may be true'.2 Here we attempt to examine the truth of Rose's conclusions.