Inter Arm Blood Pressure Difference And The Risk Of Cardiovascular Disease

The link between inter-arm blood pressure and mortality was recently analyzed in a cohort study, among the people who are at a greater risk of cardiovascular diseases. Results revealed that 60% of 3,350 participants had systolic IAD, indicating that differences existed in blood pressure between both arms of 5 mm Hg, increasing the risk of mortality from cardiovascular death up to 10 years.

The study was conducted by Christopher Clark at the University of Exeter Medical School and was published in the British Journal of General Practice (BJGP). It included 3,350 voluntary participants who were contacted through community health indexes and local advertising from Glasgow, Edinburgh, and Lanarkshire in Central Scotland. The participants were healthy and free from any previous vascular diseases and were on average 61.9 years old, with most of them being females.

The participants were assessed for their systolic blood pressure through Doppler probes and aneroid desk sphygmomanometers, after being given supine for no less than five minutes. They were tested in a set pattern with their right arm and left arm being tested first and then their left leg and right leg. Their ankle pressure was then tested, along with their brachial systolic and diastolic blood pressure. They were also asked to fill a questionnaire based on the British Hypertension Society guidelines as well as the NICE guidelines. A follow up session later took place after a period of 3 months, 1 year and 5 years, through telephone calls, after being randomly assigned to placebo or aspirin at special clinics. The clinical trial took place from April 1998- October 2008.

Former studies have displayed the link between pre-existing diseases. According to the National Institute for Health and Clinical Excellence (NICE) guidelines, ‘a difference of 10 mm Hg may be considered normal,15 mm Hg may indicate increased risk of vascular disease and 20 mm Hg warrants specialist investigation.’

Many disagreements and uncertainties have come about regarding the guidelines, with some disagreeing about both arms being taken into account while others not approving the guidelines providing written advice as opposed to verbal one. Previous studies have also indicated how a small difference which might occur is considered ‘normal’, as opposed to the new findings, which show that even a small reading could pave the way for further problems. Thus, it is advisable to test both arms in order to avoid complications and further added diagnoses.

The study teaches us the importance of measuring blood pressure in both arms when assessing hypertension during initial assessment, in order to get an accurate result. Blood pressure is constantly changing and cannot be disregarded or overlooked at any cost. Clark states that, ‘For accuracy, to overcome natural blood pressure fluctuations, it is important to test both arms simultaneously to confirm any difference.’ The reasons for one arm not displaying reliable and accurate results could be many, ranging from excessive fat to arteries being blocked. Our lifestyle also tends to affect the results. Those who are older, are regular smokers and suffer from diabetes and particularly hypertension, are at an even greater risk for having a difference between the two arms. Lack of exercise also greatly contributes to the results  as well as the factor of high cholesterol level.

Many times, clinicians do not conduct this assessment and tend to overlook it due to time constraints or lack of awareness, even when they are provided with financial incentives. General Practitioners need to take these findings a little more seriously and adopt the guidelines in their general practice.

William O’ Neil, professor of cardiology and executive dean of clinical affairs at the University of Miami Middle School, says, ‘Traditionally most people just check blood pressure in one arm, but if there is a difference, then one of the arteries has diseases in it.’

The study also consisted of a few limitations and drawbacks. Atrial fibrillation was not prevailing in the study and the figures which were reported were comparing the results with other large cohort studies.

The research has been funded by RCGP, the South West GP Trust, NIHR and the NIHR CLAHRC South West Peninsula (PenCLAHRC). The cohort was from the Aspirin for Asymptomatic Atherosclerosis (AAA) trial and was conducted by the University of Edinburgh and funded by the British Heart Foundation.

Hypertension tends to affect at least 20% of adults all over the world and is rated as the third leading cause of disability. It can damage the brain and cause various problems, such as dementia, and severe hypertension can even lead to kidney failure. Many patients go untreated since it is not taken that seriously. A better understanding of the problem and knowledge of the implications of the disease can lead to improvements in following the guidelines.

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