Normal hemoglobin level and coronary heart disease

Abstract

An attempt has been made to test hemoglobin level for the possibility of being a risk factor in the genesis of ischemic heart disease (IHD). This was necessary since some case-control studies and a few observations made on the distribution of the disease, as well as the analysis of cross-sectional data from the Los Angeles Heart Study (LAHS), suggested that such risk may exist.This report shows the analysis of the 16-yr follow-up data from the LAHS, which includes comparison of the incidence of IHD according to the initial level of hemoglobin in a sample of 1859 men, and carrying out the stepwise discriminant analysis between subjects who developed the disease and those who remained free. Eleven variables measured at entry were included in the discriminant analysis: age, race, cholesterol, systolic blood pressure, diastolic blood pressure, hemoglobin, hematocrit, RBC count, socioeconomic level, Sheldon weight index, and job activity.The results show that none of the three related variables—hemoglobin, hematocrit, and RBC count—contributes significantly to the development of IHD. Only age, race and cholesterol level can discriminate independently between subjects who developed the disease and subjects who remained free. In addition, three other variables—systolic BP, Sheldon weight index, and job exercise—can discriminate between the two groups only when considered individually without accounting for the effect of other variables.The earlier findings in case-control studies and in our cross-sectional data may, therefore, be interpreted as that hemoglobin possibly rises after the occurrence of IHD, or secondary to changes in the levels of the other risk factors. Thus it may be a consequence of, rather than a risk for, the disease, and its associations with some of the risk factors revealed previously are of no causal significance in the genesis of this disease.