Blood Pressure, Co-morbidities & Outcomes in Older Populations

Abstract

Hypertension is the most common chronic disease, with a global diagnosed prevalence of 70% by age seventy. Blood Pressure (BP) measures systemic arterial pressure and tends to increase with age from middle into older age. Higher BPs are clearly associated with higher cardiovascular and overall mortality in middle and early old age. However, BP trends and outcomes at advanced ages (over 75 years) have been less clear. This thesis aimed to: 1. estimate long term BP trajectories in older populations, including with proximity to death 2. test associations between longer term BP decline and clinical outcomes, including in population-representative older adults with specific co-morbidities 3. test whether declining BP is an independent predictor of outcomes, after accounting for commonly used clinical measures of impaired BP homeostasis The thesis reports epidemiological analyses ranging from large-scale, representative primary care populations to detailed research cohorts with systematic BP measures. The results show that BP tends to peak at advanced ages, followed by a decline lasting 9 or more years before death. This pattern of decline occurs irrespective of anti-hypertensive treatment. BP declines are more marked in frail groups, and with certain diseases including dementia. Older groups (aged over 75 years) with systolic BPs lower than 130mmHg experienced increased overall mortality compared to those with systolic BP 130 to 140 mmHg consistently across analyses. Declining BP over several years may be a better predictor of mortality outcomes than orthostatic hypertension. The results suggest that that declining blood pressures at advanced ages may constitute a distinct syndrome. Older people with a diagnostic label of hypertension without current elevated clinical BPs who have declining BP trends may be at increased risk of adverse outcomes and may require a different approach to clinical management.