In elderly, low BP may confer mortality risk
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In older patients, lower BP was associated with elevated risk for all-cause mortality. Additionally, age, not frailty, demonstrated a stronger correlation to mortality in relation to systolic and diastolic BP.
According to findings published in Age and Ageing, older adults with systolic BP of 140 mm Hg to 149 mm Hg experienced lower risk for all-cause mortality (HR in nonfrail adults = 0.95; 95% CI 0.93-0.98; HR in mildly frail adults = 0.88; 95% CI, 0.85-0.91) compared with patients with systolic BP of 130 mm Hg to 139 mm Hg.
Also, compared with systolic BP 130 mm Hg to 139 mm Hg, those with 150 mm Hg to 159 mm Hg had lower risk for all-cause mortality (HR in nonfrail adults = 0.94; 95% CI, 0.92-0.97; HR in mildly frail adults = 0.88; 95% CI, 0.85-0.91; HR in adults with moderate to severe frailty = 0.84; 95% CI, 0.77-0.92).
Only patients who were not frail or had mild frailty experienced mortality associated with higher systolic BP, which became statistically significant at 170 mm Hg in the nonfrail (HR for 170-179 mm Hg vs. 130-139 mm Hg = 1.09; 95% CI, 1.04-1.13) and at 180 mm Hg in patients with mild frailty (HR for 180-189 mm Hg vs. 130-139 mm Hg = 1.11; 95% CI 1.04-1.19).
Elevated BP and mortality
Moreover, in patients aged 85 years or older, researchers observed no increase in all-cause mortality risk associated with higher systolic BP, even in BP of 180 mm Hg or more. However, risk for CV outcomes increased with systolic BP greater than 150 mm Hg.
Systolic BP 120 mm Hg to 129 mm Hg, systolic BP less than 120 mm Hg and diastolic BP less than 80 mm Hg were associated with elevated risk for all-cause mortality in patients older than 75 years, regardless of frailty.
“In this large study of routine clinical data from 415,980 population-representative primary-care patients aged 75 years and above, we have shown that risks of cardiovascular outcomes increase with systolic BPs above 150 mm Hg across categories of frailty,” Jane A.H. Masoli, MBChB, geriatrician and NIHR Doctoral Research Fellow in the epidemiology and public health group at University of Exeter Medical School, United Kingdom, and colleagues wrote. “However, this was not accompanied by raised all-cause mortality, particularly for those with established frailty or above 85 years old. Relative systolic hypertension (systolic BP 140-160 mm Hg) was associated with the lowest all-cause mortality across all categories of frailty, with no increased mortality risk with hypertension in moderate to severe frailty.”
Diastolic BP effect
In addition, elevated diastolic BP did not affect outcomes for patients with frailty aged 75 to 84 years or those older than 85 years. However, diastolic BP of at least 90 mm Hg was associated with increased risk for all-cause mortality in both nonfrail and mildly frail adults younger than 85 years.
“Systolic BPs below 130 mm Hg and diastolic BPs below 80 mm Hg were consistently associated with excess mortality risk, independent of systolic BP trajectory,” the researchers wrote. “This provides compelling evidence that this association is not solely an artefact of reverse causation associated with terminal BP decline.”
Researchers stratified patients by baseline electronic frailty index to assess the relationship between BP, frailty, age and CV events and all-cause mortality.
“Internationally, guidelines are moving towards tight blood pressure targets, but our findings indicate that this may not be appropriate in frail older adults,” Masoli said in a press release. “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 personalized blood pressure management in older adults.” – by Scott Buzby
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Perspective
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This observational study adds to data from HYVET, SPRINT and SYST-Eur by examining BP levels and outcomes in a predominantly older cohort. This study is not randomized and is observational in nature, but it has a very large cohort of over 400,000 people observed over a 10-year period. It confirms data from HYVET and SYST-EUR that systolic BP levels around 150 mm Hg provide reduced CV risk, but in contrast to SPRINT, suggests that lower systolic BPs below 130 mm Hg are associated with higher CV events. One major difference, as the authors point out, is the cohort studied and definition of frailty used.
The optimal level of BP depends on several factors in older people. Each older adult needs to be evaluated by level of functionality, arterial compliance and frailty. Those with very poor arterial compliance, as seen in the SHEP trial, have a very difficult time achieving systolic BP levels in the high 130s to low 140s, with significant side effects versus those with pulse pressure < 70 mm Hg who are more physically fit. Such individuals have significant CV risk reduction at levels below 140 mm Hg. Data from SHEP in such people would say anything below 160 mm Hg would generate CV risk reduction.
Those with better arterial compliance who are functional do well with BP reduction down to a range of 128-135 mm Hg. However, the number of people well over 80 years that have BP levels below that are small and have to be judged based on the individual treated. So many things have to be taken into account including concomitant diseases, orthostasis and clinical judgement to slowly achieve BPs in the 130s.
The impact of frailty on BP strategy clearly depends on the definition of frailty used. The one used in this study is different from that used in SPRINT, hence, one will get different results. Frailty alone should not be the only determinant of BP but overall risk vs. benefit should. While in SPRINT, a subgroup of very frail patients by the criteria used by those investigators did well, in this study, that was not so much the case. Hence, clinical judgement is needed, and one should always try to get BPs below 140 if at all possible in people up to age 80 years. After that, the clinician has to use judgement.
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