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“Ideal” BP in the Elderly – what is the target again?

22nd April 2019, Dr Chee L Khoo

Hardening of the arteries” is pretty much inevitable when one gets older. A majority of our patients >70 years old are on anti-hypertensive treatment. The problem is they keep changing the targets we are meant to be aiming for in this cohort of patients. The ACC/AHA High Blood Pressure guidelines 2017 recommends 130/80 mmHg even for patients >70 years old (1). On the other hand, the European Society of Cardiology/European Society of Hypertension (ESC/ESH) recommends a systolic target of 140 mmHg for patients >70 years old (2). Does it make that much difference anyway?

Whenever there are differences in opinion in international guidelines, it usually means there is a lack of data or conflicting results coming from different trials. Naturally, the differences arise because of differences in subject selection, methodology and definitions. Level one evidence from randomised control trials is often the gold standard when we seek answers to research questions but sometimes, real world evidence looking at patients in real practices is necessary to back up what guidelines suggest. The Berlin Initiative Study (BIS) is well suited to provide such evidence (3).

The BIS is an ongoing prospective cohort study initiated in 2009 in Berlin, Germany to explore the epidemiology of chronic kidney disease (CKD) in elderly. It followed the natural course of CKD and assesses associated risk factors as well as cardiovascular outcomes and death. In a recent population-based observation analysis, a subgroup of patients from the BIS who were on anti-hypertensive therapy were investigated to assess whether BP values below systolic BP (SBP) 140mmHg and diastolic BP (DBP) 90mmHg during anti-hypertensive treatment was associated with a decreased risk of all-cause mortality in community-dwelling older adults (4).

They classified patients into whether their baseline BP values were (i) “normalised BP”, defined as SBP <140mmHg and DBP <90mmHg or (ii) “non-normalised BP”, defined as SBP >_140mmHg or DBP >_90mmHg. They followed the the ESC/ESH recommendations for routine BP measurement: BP was calculated as the mean of two office measurements within 10min. Patients were seated before measurement for 5 min, legs uncrossed, and not talking. This is achievable in general practice.

Contrast the requirements under the ACC/AHA for measurement of BP in the office:

  1. Have the patient relax, sitting in a chair (feet on floor, back supported) for >5 min.
  2. The patient should avoid caffeine, exercise, and smoking for at least 30 min before measurement.
  3. Ensure patient has emptied his/her bladder.
  4. Neither the patient nor the observer should talk during the rest period or during the measurement….
  5. At the first visit, record BP in both arms. Use the arm that gives the higher reading for subsequent readings.
  6. Separate repeated measurements by 1–2 min
  7. Use an average of ≥ 2 readings obtained on ≥ 2 occasions to estimate the individual’s level of BP.

The median follow-up time was 73 months (66–77 months), generating a total follow-up of 8853 person-years. During the study period 469 patients died, resulting in an incidence rate of 53.0 per 1000 person-years.

Overall topline results

Overall, instead of decreased mortality, compared with non-normalised BP, normalised BP was associated with an 26% increased risk of all-cause mortality (crude incidence rates 60.3 vs. 48.5 per 1000 person-years). The number needed to harm (NNH) was 64 after 3 years and 34 after 6 years. Most of this increased risk was driven by those with systolic BP < 130 mm Hg.

Effect of previous CV events

In patients without previous CV events, there were no difference in mortality rates between the non-normalised and normalised BP groups. On the other hand, in patients who had a history of cardiovascular events, normalised BP increased the adjusted all-cause mortality risk by a whopping 61%.

Effect of age

In the 70-79 year olds, there was a tendency towards a decreased mortality favouring the normalised BP group although it did not reached statistical significance. Most importantly, in the >80 year olds, normalised BP was associated with a 40% increased all-cause mortality rate. If the 80 year old had previous CV events, the all-cause mortality was increased by 61% if the BP was normalised.

This study had a decent average follow up duration of 73 months., The increased in all-cause mortality rate is consistent with previous other similar studies. In a cohort of elderly patients (mean age 82 years) treated with antihypertensive drugs in the UK, the risk of all-cause mortality after a mean follow-up of 4.4 years was increased with lower and higher SBP values when compared with SBP 145–155mmHg (5). in a cohort of elderly individuals, (mean age 92 years) in China, the risk of all-cause mortality at 3 years was also increased with lower and higher SBP values when compared with SBP 143.5mmHg (6).

On the other hand, in the Hypertension in the Very Elderly Double Blind Trial (HYVET) targeting a BP of 150/80mm Hg in patients aged 80 years or older led to a 21% decreased risk of all-cause mortality (7). In the SPRINT trial, patients aged 75 years or older with SBP >130mmHg, targeting SBP <120mmHg also led to a 33% decreased risk of all-cause mortality (8). Both studies excluded many patients with common co-morbidities (e.g. diabetes, heart failure, strokes, dementia etc) and had a relatively short follow up duration (HYVET 1.8 years and SPRINT 3.1 years).

Access the abstract here.

References:

  1. Whelton et al.  2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: Executive Summary. A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. JACC Vol. 71, No. 19, 2018
  2. Bryan Williams, Giuseppe Mancia, Wilko Spiering et al. 2018 ESC/ESH Guidelines for the management of arterial hypertension. European Heart Journal, Volume 39, Issue 33, 01 September 2018, Pages 3021–3104
  1. Schaeffner ES, van der Giet M, Gaedeke J, et al. The Berlin Initiative Study: the methodology of exploring kidney function in the elderly by combining a longitudinal and cross-sectional approach. Eur J Epidemiol 2010;25:203–210.
  2. Antonios Douros, Markus Tolle, Natalie Ebert et al. Control of blood pressure and risk of mortality in a cohort of older adults: the Berlin Initiative Study. European Heart Journal (2019) 0, 1–8
  3. Delgado J, Masoli JAH, Bowman K, et al. Outcomes of Treated hypertension at age 80 and older: cohort analysis of 79,376 individuals. J Am Geriatr Soc 2017;65: 995–1003.
  4. Lv YB, Gao X, Yin ZX, et al. Revisiting the association of blood pressure with mortality in oldest old people in China: community based, longitudinal prospective study. BMJ 2018; 361:k2158.
  5. Beckett NS, Peters R, Fletcher AE, et al. Treatment of hypertension in patients 80 years of age or older. N Engl J Med 2008;358:1887–1898.
  6. Williamson JD, Supiano MA, Applegate WB, et al. Intensive vs standard blood pressure control and cardiovascular disease outcomes in adults aged >/=75 years: a randomized clinical trial. JAMA 2016;315: 2673–2682.

 

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