Ascertainment of End Points
The primary end points for this study were newly diagnosed coronary
heart disease (nonfatal myocardial infarction or death from
coronary causes) and total cardiovascular events (myocardial infarction,
death from coronary causes, coronary revascularization, angina,
congestive heart failure, stroke, or carotid revascularization) that
occurred after the return of the base-line questionnaire but before
August 27, 2000. Newly diagnosed cardiovascular events were identified
on the basis of annual mailed follow-up questionnaires (response
rates have been above 95 percent), and permission to review
medical records was requested. Study physicians with no knowledge
of the self-reported risk-factor status reviewed the records. The diagnosis
of nonfatal myocardial infarction was confirmed if data in
the hospital record met standardized criteria of diagnostic electrocardiographic
changes, elevated cardiac-enzyme levels, or both.
10
Treatment with coronary or carotid revascularization was confirmed
by documentation of the procedure in the medical record. The presence
of angina was confirmed by hospitalization and confirmatory
evidence on angiography, diagnostic stress test, or diagnosis by a
physician and medical treatment. The occurrence of stroke was confirmed
by documentation in the medical record of the rapid onset
of a neurologic deficit consistent with stroke and lasting at least 24
hours or until death. The presence of congestive heart failure was
confirmed by hospitalization and diagnostic confirmatory tests.
Fatal coronary disease was considered confirmed if there was documentation
in the hospital or autopsy records or if coronary disease
was listed as the cause of death on the death certificate and evidence
of previous coronary disease was available. For deaths from other
cardiovascular causes, a review of confirmatory evidence by physician-
adjudicators was required.