The evidence concerning an association between gallbladder disease and coronary heart disease is critically reviewed. A classification of disease associations is first proposed. Real associations between two diseases are based on the promotion of one disease by the other or on the sharing of etiological or nonetiological factors. False associations may result from chance error, selection, and diagnostic confusion.
The statistical evidence for an association between cholecystitis and cholelithiasis and coronary heart disease, based on autopsy, clinical, and epidemiologic findings, is incomplete and inconclusive so far. The weight of evidence suggests that little if any association exists over and above that which appears because the incidence and the prevalence of both diseases rises with age.
There is some basis for a real association in that under certain circumstances experimental disturbance of the gallbladder appears reflexly to modify cardiac rhythm and coronary blood flow, especially where the coronary circulation is already compromised. This has not yet been clearly shown to occur in free-living human subjects. Other uncontrolled clinical observations of improvement in cardiac status after removal of diseased gallbladders are too easily explained away to permit the inference that there is a special relationship between the gallbladder and the heart.
Shared etiological factors may be represented by the relationship of both diseases to age and obesity and possibly to short stature, blood pressure, race, diabetes mellitus, and number of pregnancies. The mutual relationship to blood pressure and, obviously, to number of pregnancies has so far been found only in women, so that an association between the diseases may be more apt to occur in women only. None of these factors is a sufficiently powerful determinant of both diseases to produce a marked association.
All bases for a false association can be found in the literature. Diagnostic confusion is a particular problem with these diseases since there is overlap, not only in the pain produced, but also in the response to nitroglycerine and possibly in their effects on serum transaminase.
It is concluded from the meager evidence to date that there is no strong association between gallbladder disease and coronary heart disease. There exists some basis for a weak association, both in shared etiological factors and in a possible aggravation of cardiac symptoms by a diseased gallbladder.