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—Mr Leigh suggests that the association between occupational status and fatal coronary heart disease (CHD) observed in our study might be overstated because of a failure to control for confounding by level of schooling. For this to have accounted for the findings, schooling must have been related to occupation and, in addition, must be associated with risk of fatal CHD. Regarding the former, nobody would disagree with the statement that level of schooling is related to occupational status. With respect to the latter, however, to be a confounder, the association of schooling with CHD must be independent of the relationship with occupational status. While we agree that level of schooling, as a marker for socioeconomic status, is related to risk of CHD, we know of no evidence that schooling per se is an independent causal risk factor. Further, our study did control for a strong correlate of socioeconomic
Julie E. Buring, Denis A. Evans, Michael Fiore, Bernard Rosner, Charles H. Hennekens. Occupation and Coronary Disease: Schooling as a Confounder-Reply. JAMA. 1988;259(10):1497. doi:10.1001/jama.1988.03720100018019