The long-term prognostic significance of repeated blood pressure measurements in the elderly: SPAA (Studio sulla Pressione Arteriosa nell'Anziano) 10-year follow-up

Abstract

Background: In young and middle-aged people, both systolic (SBP) and diastolic (DBP) blood pressure have a continuous, strong, and independent relationship with subsequent cardiovascular morbidity and mortality. These relationships are not well documented in older people and, until now, studies in the elderly do not provide homogeneous results on the importance of DBP compared with SBP as a cardiovascular risk factor.

Objective: To determine whether SBP and DBP are independent indicators of mortality risk in the elderly.

Design: An observational prospective cohort study to analyze the long-term prognostic significance of repeated SBP and DBP measurements in the elderly.

Patients and methods: A total of 3858 outpatients 65 years or older (mean age [SD], 72.9 [4.9] years, 43.5% men) were selected randomly by 444 Italian National Health Service general practitioners in 1983. The population was followed up for 10 years. Crude and adjusted incidence rates of total and cardiovascular mortality were analyzed for classes of SBP and DBP based on the values recorded at the 2 initial visits 1 week apart and those measured during the first 12 months of follow-up.

Results: During the 10-year follow-up, 74 patients (1.9%) were lost to follow-up and 1561 (41.3%) died, 709 (45.4% of all deaths) from cardiovascular causes. A positive continuous, graded, strong, and independent association was observed with both total (P<.001) and cardiovascular (P<.001) mortality for SBP but not for DBP. The pattern was similar in both sexes, in persons younger and older than 75 years, regardless of preexisting cardiovascular diseases, and whether they had been receiving antihypertensive treatment at baseline. There was no J-shaped mortality curve in the subjects with the lowest SBP and DBP.

Conclusions: These findings suggest that SBP, but not DBP, is a strong, positive, continuous, independent indicator of mortality risk in the elderly and should be stressed much more than DBP in the diagnosis and treatment of hypertension in this age group.