Objective: To determine the relation between mortality from ischaemic heart disease (IHD) and treated blood pressure at different ages.
Design: Prospectively, 6216 patients were studied for a mean of 107 months.
Setting: Of the total patients, 95% were followed in five hospital-based hypertension clinics and the remainder in four group general practices.
Patients: Respectively, 2250 and 2126 hypertensive men and women aged < 60 years and 822 and 1018 aged > or = 60 years.
Main outcome measures: Mortality (any mention on the death certificate) from IHD.
Results: Four hundred and sixty-seven patients died with IHD mentioned on the death certificate. The relation between both diastolic blood pressure (DBP) and systolic blood pressure (SBP) during the first 3-12 months of treatment and subsequent IHD mortality was examined. Under the age of 60 years the relative hazard rate (RHR) for death from IHD tended to increase with DBP in both men and women. Above the age of 60 years there was no important or significant relation between IHD mortality and treated DBP. For SBP there was no reduction in the positive relation between IHD mortality and blood pressure in the older age groups. The RHR for SBP ranged between 1.008 and 1.021 in men and women over and under the age of 60 years.
Conclusions: The positive relation between DBP and IHD mortality decreased with increasing age and, in women aged > or = 60 years, even inverted, partly explaining the negative relation reported between DBP and total mortality in the very old.