Our earlier studies indicated a significant association between the type A behavior pattern and both the prevalence and incidence of clinical coronary heart disease (CHD). Pattern A is characterized by enhanced aggressiveness, ambitiousness, competitive drive, and chronic sense of time urgency. The converse, more relaxed, type B subject exhibited substantially lower CHD incidence and less basic atherosclerosis. The association of various facets of pattern A with increased levels of CHD risk factors and higher CHD prevalence has been confirmed by other investigators.

Keys recently observed that the classical risk factors account for only about half of the CHD incidence in middle-aged American men and that other variables contribute significantly to the incidence. The present findings indicate that the behavior pattern is one such important factor.

Methods and materials

The Western Collaborative Group Study (WCGS) was initiated in 1960-1961 as a prospective epidemiological investigation of CHD incidence in 3,524 men, aged 39 to 59 years at intake, and employed in ten California companies. The methodology had been described in previous reports.3'4 Comprehensive data were obtained at intake and annually until the study was terminated, providing eight to nine years of follow-up, at which time a sufficient incidence of CHD had occurred as to make it unlikely that further follow-up would provide additional significant information. The intake studies were accomplished over an 18-month period from June 1960 to December 1961. Annual resurveys were done during the calendar 12-month period, ending in December 1969, during which time the subjects were studied in order of intake, with minor exceptions.