Mortality risk increases in older patients with low BP

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A large-scale study led by the University of Exeter and funded by NIHR, analysed 415,980 electronic medical records of older adults in England. The research was conducted after some countries have changed blood pressure guidelines to encourage clinicians to take measures to reduce blood pressure in a bid to improve health outcomes.

UK blood pressure guidelines are within safe parameters for all. However, previous research has not considered the impact on frail older adults, who are often omitted from trials.

The team found that people aged 75 or over with low blood pressure (below 130 / 80) had increased mortality rates in the follow-up, compared to those with normal blood pressure. This was especially pronounced in ‘frail’ individuals, who had 62% increased risk of death during the ten-year follow-up.

Although high blood pressure increased risk of cardiovascular incidents, such as heart attacks, it was not linked to higher mortality in frail adults over 75. Older people aged 85 and over who had raised blood pressure actually had reduced mortality rates, compared to those with lower blood pressure, regardless of whether they were frail or not.

Jane Masoli, a geriatrician and NIHR doctoral research f ellow, who led the study as part of her PhD at the University of Exeter, said: “Internationally, guidelines are moving towards tight blood pressure targets, but our findings indicate that this may not be appropriate in frail older adults. We need more research to ascertain whether aggressive blood pressure control is safe in older adults, and then for which patient groups there may be benefit, so we can move towards more personalised blood pressure management in older adults.”

She added: “We know that treating blood pressure helps to prevent strokes and heart attacks and we would not advise anyone to stop taking their medications unless guided by their doctor.”

Background: Blood pressure (BP) management in frail older people is challenging. An randomised controlled trial of largely non-frail older people found cardiovascular and mortality benefit with systolic (S) BP target <120 mmHg. However, all-cause mortality by attained BP in routine care in frail adults aged above 75 is unclear.

Objectives: To estimate observational associations between baseline BP and mortality/cardiovascular outcomes in a primary-care population aged above 75, stratified by frailty. Methods: Prospective observational analysis using electronic health records (clinical practice research datalink, n = 415,980). We tested BP associations with cardiovascular events and mortality using competing and Cox proportional-hazards models respectively (follow-up ≤10 years), stratified by baseline electronic frailty index (eFI: fit (non-frail), mild, moderate, severe frailty), with sensitivity analyses on co-morbidity, cardiovascular risk and BP trajectory.

Results: Risks of cardiovascular outcomes increased with SBPs >150 mmHg. Associations with mortality varied between non-frail <85 and frail 75–84-year-olds and all above 85 years. SBPs above the 130–139-mmHg reference were associated with lower mortality risk, particularly in moderate to severe frailty or above 85 years (e.g. 75–84 years: 150–159 mmHg Hazard Ratio (HR) mortality compared to 130–139: non-frail HR = 0.94, 0.92–0.97; moderate/severe frailty HR = 0.84, 0.77–0.92). SBP <130 mmHg and Diastolic(D)BP <80 mmHg were consistently associated with excess mortality, independent of BP trajectory toward the end of life.
Conclusions: In representative primary-care patients aged ≥75, BP <130/80 was associated with excess mortality. Hypertension was not associated with increased mortality at ages above 85 or at ages 75–84 with moderate/severe frailty, perhaps due to complexities of co-existing morbidities. The priority given to aggressive BP reduction in frail older people requires further evaluation.

David Melzer, David Strain, Luke Pilling, Joao Delgado, Jane A H Masoli

University of Exeter material

Age and Ageing abstract

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