Hypertension Detection and Follow-up Program (HDFP)

BACKGROUND:

Published data from the Veterans Administration Cooperative Study of Hypertension demonstrated that reduction in morbidity and mortality could be attained by treating men with fixed diastolic blood pressure over 105 mm Hg. Similar trends occurred for those with fixed diastolic blood pressure between 90 and 104 mm Hg. Results and current trends from other studies supported these findings. However, prior to inception of the Hypertension Detection and Follow-up Program (HDFP), it was not known whether benefits from antihypertensive therapy applied to all hypertensives in the general population and whether making use of existing medical knowledge could significantly reduce morbidity and mortality from hypertension in communities.

Recognizing this need, NHLBI initiated the pilot activities of the HDFP to characterize significant operational, socioeconomic, and motivational factors that would influence the acceptance of antihypertensive therapy in the defined populations within which the controlled clinical trial would take place and to obtain baseline information necessary to the undertaking of the clinical trial, which was to determine whether a practical, intensive, and antihypertensive program could significantly reduce morbidity and mortality in hypertensives in the general population.

The planning of the trial, including the development of a protocol and manual of operations, began in 1971. Between February 1973 and May 1974, 158,906 persons were screened for high blood pressure in 14 communities. A total of 10,940 hypertensive participants were randomized.

The primary hypothesis tested by the trial was that intensive blood pressure control under stepped care for five years could significantly reduce mortality compared with that under referred-care. Stepped-care was the method of treatment in HDFP clinics in which a diuretic was given initially and additional antihypertensive agents were added in a time-structured, stepwise fashion until goal blood pressure was achieved. Referred-care represented referral to private physicians and other community sources of care. Participating in this study were 14 clinical centers, a coordinating center, ECG center, central laboratory, and monitoring laboratory.

The clinical phase of the trial ended in May 1982. The project was extended into 1983 in order to continue the surveillance of mortality and blood pressure control.

DESIGN NARRATIVE:

The trial was a randomized, non-blind, fixed sample trial with single intervention and control groups. The intervention group received stepped care from the clinical trial clinics (see Background, below), while those in the control group were referred to their own physicians. Each community contributed both stepped-care and referred-care participants, but for analysis purposes, the groups were pooled into two groups. The primary endpoint was mortality. The effects of stepped- vs. referred-care were also assessed on intermediate and secondary factors, including nosologic codes of specific causes of mortality, nonfatal myocardial infarction, stroke, hypertensive heart disease, and EKG abnormalities.