Are Elderly People at a Lower Risk of Mortality Due to High Blood Pressure?

According to a recent study published in the Oxford Academic by Dr Jane Masoli and her team of researchers, found some astonishing revelations regarding the relation of blood pressure and mortality in elderly people, that is people above 75 years of age.

High blood pressure for too long may result in damaged blood vessels. It can also cause other diseases like heart failure, kidney diseases, stroke etc. In multiple cases high blood pressure does not display any symptoms. Only routine checkups may warn a person as to what precautionary measures may be implemented.

Blood pressure is usually measured in millimeters of mercury [mm Hg]. Systolic pressure represents the top number, the pressure in arteries as the heart contracts. Diastolic pressure represents the lower number of BP when the heart is in the middle stages of contractions and extractions. High blood pressure is also known as ‘Hypertension’. Centers for Disease Control and Prevention (CDC) has recently disclosed that 29% of the United States population suffers from hypertension. A very high blood pressure of 180/120 mm Hg may result in the following illnesses including blurred vision, dizziness, nose bleeding, heart palpitations etc.

However, the study has concluded that a blood pressure greater than 130/80 on adults aged less than 75 was linked with increased mortality. Though adults aged above 75 with moderate to extreme frailty and all the adults ages above 85 showed no increased signs of mortality with increased blood pressure. A total of 4,15,980 adults above the age of 75 we analyzed in the study. The research also admits that more study needs to be done to properly address the connection between increased blood pressure and mortality in adults aged above 75.

Hypertension has been identified as the most common chronic disease amongst elderly frail people. The disease is known to be prevalent in more than 75% of the elderly aged above 80. The likely form of treatment for high blood pressure in elderly people remains uncertain compared to young people, below 70. The study also suggests that extreme precautions should be taken while initiating randomized controlled trial’s (RCT’s), and applying the results to a wider range of sample. One more reason for taking such extreme caution may be that participation of older frail patients in clinical trials is extremely low due to co-morbidities, low life expectancy etc. As a result, multiple randomized controlled trials have often found totally contrasting results on Hypertension prognosis.

The authors of the study have said, “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 coexisting morbidities. The priority given to aggressive [blood pressure] reduction in frail older people requires further evaluation.”

Dr Jane Masoli further added, “Internationally, guidelines are moving towards tight blood pressure targets, but our findings indicate that this may not be appropriate in frail older adults.”

The main data source for the research has been clinical practice research datalink (CPRD). According to researches CPRD data is ‘representative of age, sex and ethnicity’. The study was meant to as inclusive as possible and thus CPRD data was analyzed between Jan 2000 till Nov 2014. The only criteria for the study was that the person be above the age of 75 years and has at least three blood pressure readings in the past 3 years.

Data Sources

Randomized Clinical Trails that have examined hypertension in older adults reflect inconclusiveness as international standards for high blood pressure among older adults, that is above 75, is ≤130/80 [4] to ≤150/90 mmHg. Systolic BP Intervention Trial (SPRINT) has concluded that a systolic blood pressure of more than 120 mm Hg is the main cause of reduced cardiovascular ailments and mortality rather than of more than 140 mm Hg. However, the main concern with study is believed to be that it excluded severe frailty patients, dementia and older people in nursing homes.

In the study presented by Dr Jane Masoli and her team, older people with a systolic blood pressure of more than 135 mm Hg was known to have increased mortality, while considering the same sample it was also revealed that older people with a systolic blood pressure of more than 155 mm Hg experienced more cardiovascular events. Recently conducted analysis also found that there was no increased mortality in in older patients with frail health and non-frail health when compared to systolic blood pressure on more or less than 140 mm Hg.

Blood Pressure

Median systolic blood pressure and diastolic blood pressure were used from routine clinical blood pressure measurements were analyzed as a part of this study. The median BP is also assumed to have negated any effects caused on the data due to acute illness. Values for systolic blood pressure were bifurcated into classes of 10 mm Hg, namely 120-129 mm Hg, 130-139 mm Hg, 140-149 mm Hg, 150-159 mm Hg etc. The above-mentioned categories were then compared to the standard 130-139 mm Hg as recognized by international standards. Diastolic blood pressure was then analyzed in the same way, 80-90 etc., with keeping more than or equal to 90 as the international standard prescribed.

Electronic Frailty Index

Using the cumulative deficit method electronic frailty index [eFI] has been developed. Electronic Frailty Index assesses 36 various clinical deficits such as symptoms, clinical signs, diseases, disabilities and impairment in to electronic records and the bifurcates them in categories such as fir, mild, moderate and severe frailty.

 

Results as Per Derived by the Study:

All-cause mortality was the primary cause of death as identified using the data from UK Office for National Statistics.

Secondary causes of death include cardiovascular events: stroke (ischemic or intracerebral hemorrhage), hearth failure and myocardial infarction or cardiac revascularization procedure (MIP). All diagnostics have been based on ICD-10 classification for stroke and MI and quality of outcomes framework (QOF), used in UK primary care to generate databases for specific health conditions.

The median age of the study was 79.5 years which included a follow up of up to 10 years. At the start of the study 55.1% of hypertension patients found to be non-frail as opposed to 75.6% who were found to be severely frail. However, with increasing frailty the SBP and DBP were found to be consistently lower.

Older adults above the age of 85 have shown no signs of increased blood pressure, even with the systolic blood pressure as high as 180 mm Hg. High systolic blood pressure was found to be the cause increased mortality in non-frail or mildly frail patients.  Lower SBP in the range of 120-129 mm Hg was found to increase mortality in all the frail patients above the age of 75. For patients who has been identified as frail at the start of the study, increased diastolic blood pressure had no effects on patients above the age of 75. An increased DBP on over 90 mm Hg had an increased mortality frailty cases not aged more than 85 years.

Relation between blood pressure and cardiovascular disease have displayed a similar result between the age groups 75-84 and all the patients more than age of 85, with an increase mortality risk with systolic diastolic pressure of over 15 mm Hg.

Dr Jane Masoli also suggested, “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. 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.”

 

Conclusion

The study has further proved that, as per clinical data analyzed for 4,15,980 patients aged 75 or above, the risks a cardiovascular event drastically increased with the systolic blood pressure of over 150 mm Hg. This conclusion has been consistent within all the categories of frailty. However all-cause mortality did not see an increase with this assumption in patients with existing frailty and patients above the age of 85. Systolic hypertension [SPD 140-160] was related to the lowest number of all-cause mortalities across all categories of frailty.

The average follow up for each patient has lasted 4.46 years and a maximum of 10 years, which is much lengthier than any existing RCT’s. Primary and secondary care CPRD data has been linked to clinical outcomes. Reliable data from the National death certification mortality was also taken in to account for this experiment. Observational data which may not be accurate as compared to data generated by RCT’s is also one of the limitations of this study.

As a previous study had concluded that associations between SBP and mortality were consistent whether on antihypertensive intervention or not. However, the blood pressure results for that study were procured under clinical conditions which are generally more tumultuous for the patient taking the test. This might result in inaccuracies as compared to Randomized Controlled Trial’s which are more comfortable for the patients.

Hypertension management in older people, that fall in the frailty categories, often requires very complex and at times conflicting objectives to get the best possible treatment designed for patients. The study concludes by pointing out that increased systolic blood pressure of more than 150 mm Hg increases the risk of cardiovascular events in young people, however, has little to none effect in older frail patients above the age of 75.

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