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Low blood pressure is not an independent determinant of survival in an elderly population
W J Busby1, A J Campbell, M C Robertson
1Department of Medicine, University of Otago Medical School, Dunedin, New Zealand.
Insights
Low blood pressure in older adults does not directly increase mortality risk. Concurrent illnesses, not hypotension itself, explain the higher mortality observed in some elderly individuals with low blood pressure.
Area of Science:
- Gerontology
- Cardiovascular Health
- Epidemiology
Background:
- Low blood pressure (hypotension) in the elderly is often associated with increased mortality.
- The underlying reasons for this association, whether direct effects of hypotension or confounding factors, require clarification.
Purpose of the Study:
- To investigate whether increased mortality in elderly individuals with low blood pressure is due to hypotension or confounding variables.
- To differentiate the impact of low systolic and diastolic blood pressure on mortality risk in older adults.
Main Methods:
- A 3-year prospective cohort study of 782 community-dwelling individuals aged 70 years and older.
- Hypotension defined as blood pressure below the 10th percentile (systolic ≤ 122 mmHg, diastolic ≤ 68 mmHg).
- Mortality data collected over the follow-up period; statistical analysis using hazard ratios and confidence intervals.
Main Results:
- Low diastolic blood pressure showed a trend towards increased mortality (hazard ratio 1.85), but this association was fully explained by confounding variables.
- Low systolic blood pressure was not significantly associated with increased mortality.
- The observed increased mortality in individuals with low blood pressure was attributed to concurrent illnesses.
Conclusions:
- The increased mortality risk associated with low blood pressure in the elderly is not directly caused by hypotension.
- Concurrent illnesses are the primary confounding factors explaining the link between low blood pressure and higher mortality rates in older populations.
- Clinical focus should be on managing underlying conditions rather than solely on low blood pressure readings in this demographic.
Abstract:
The object of the study was to determine whether the increased mortality associated with low blood pressure in elderly people arises because of the adverse effects of hypotension or because of confounding variables. A community sample of 782 people aged 70 years and older was followed for 3 years. Blood pressure measurements were taken on initial assessment and hypotension was defined separately for systolic and diastolic pressures as a pressure less than the tenth percentile for the sample (systolic < or = 122 mmHg, diastolic < or = 68 mmHg). After 3 years 135 participants had died and of these 31 had low systolic or diastolic blood pressure at baseline. Low diastolic pressure was associated with an increased mortality over the 3 years (hazard ratio 1.85, 95% Confidence Interval 1.18-2.91). This increase in risk was explained by confounding variables. Low systolic pressure was not associated with increased mortality. The increased mortality of those with low blood pressure is explained by concurrent illness.