Predicting survival in CAD.

and Switzerland lie considerably below the regression line and, on the other hand, the United States much above it. As, however, CHD is a multifactorial disease for which the consumption of dairy fats or, more generally, saturated fats is not the sole risk factor, some irregularities are to be expected. Furthermore, the unavoidable inaccuracies in the statistical data emanating from various countries may be responsible for part of the scatter. In view of all this, the correlation shown in figure 4 is remarkably good (r= 0.75). The correlations alone, of course, can never establish causation. They can, however, and often do suggest hypotheses, which then can be tested by other methods. This has been in the case of the lipid hypothesis, which has evolved into a well-supported theory with important clinical and public health implications. Dr. Oster's suggestion that bovine milk xanthine oxidase could be etiologically related to atherosclerosis, and hence also to CHD, is interesting, but highly hypothetical. To be taken seriously, it would need much more supporting evidence, preferably also from some kind of human intervention trials. OsMo TURPEINEN, M.D. Department of Biochemistry Hameentie 57 00550 Helsinki 55, Finland