High blood pressure in old age: revisiting the concept “the lower, the better”
Giulia Ogliari is a geriatrician and PhD Candidate at Milan University (Italy) / Leiden University Medical Center (NL). In this blog, she introduces her recent Age & Ageing paper on blood pressure and mortality risk in geriatric outpatients in Milan.
‘’What is my blood pressure, doctor?’’ Everyone, old or young, is curious to know what their blood pressure is. And everyone is convinced that the lower their blood pressure is, the better it is. Yet, this may not be the case for the older adults.
Looking into the scientific literature on blood pressure and mortality, we encounter a paradox. High blood pressure is a preventable risk factor for premature death in middle-aged adults. Yet, population-based studies in older adults show a different picture. First, systolic blood pressure rises with age. Second, both low and high blood pressure are associated with greater mortality in adults over 85 years. Third, low blood pressure may be associated with greater mortality especially in frail older adults. In contrast, clinical trials provide evidence in favour of lowering blood pressure. However, only one out of ten older adults may be eligible for inclusion in trials.
Are the conflicting results from population-based studies and trials generalizable to the older adults clinicians face in everyday clinical practice? We explored the relationship of blood pressure and mortality in the Milan Geriatrics 75+ Cohort Study, a prospective hospital-based cohort of outpatients aged 75 years and over. In our cohort, the association of systolic blood pressure with mortality was U-shaped. Mortality was lowest at systolic blood pressure of 165 mmHg. Furthermore, the association of systolic blood pressure with mortality varied by functional and cognitive status. Higher systolic blood pressure was associated with increased survival in geriatric patients with functional/cognitive impairment.