Of particular interest was the fact that the primary risk factors appeared to be influenced by behavior. It was possible that gender differences in behavior might explain gender differences in primary coronary risk factors. Alternatively, there was some evidence that the primary coronary risk factors were not solely responsible for the etiology of coronary heart disease. Gender differences in psychosocial variables, such as Type A behavior, hostility, and occupational stress that might play independent roles in the etiology of coronary heart disease had not been systematically investigated.