Arm Position During Blood Pressure Checks May Lead to Misdiagnoses, Experts Warn

Thousands of individuals may be incorrectly diagnosed with high blood pressure due to simple procedural errors during routine health checks, according to a UK general practitioner. These common mistakes, particularly concerning arm positioning, can lead to misleading results and potentially inappropriate treatment.

Dr. Dean Eggitt, an NHS GP, emphasized the critical need for accurate blood pressure measurement to identify and manage individuals at risk of hypertension-related damage. "Over-treatment and medication-induced side effects can cause real harm, particularly in vulnerable patients," Dr. Eggitt stated. "Poor technique can ultimately result in inappropriate treatment decisions and reduce quality of life."

His warning is underscored by recent research from Johns Hopkins Medicine in the United States. The study found that allowing an arm to hang unsupported by a patient's side during a blood pressure reading can increase systolic pressure by nearly 7 mmHg. Resting the arm in the lap also led to an overestimation of systolic pressure by almost 4 mmHg.

These findings align with existing NHS guidance, which advises patients to sit upright with their arm supported on a table or desk at heart level. When an arm hangs, muscles can contract, temporarily elevating blood pressure. Conversely, resting the arm in the lap can create a greater distance from the heart, also impacting readings.

High blood pressure, or hypertension, affects approximately one in three adults in England and is a significant risk factor for stroke, heart attack, kidney disease, and dementia. The condition often goes undetected because it rarely presents with symptoms, leading to millions in England being unaware they have it.

The Johns Hopkins study, published in JAMA Internal Medicine, measured the blood pressure of 133 adults aged 18 to 80. Participants rested for five minutes before measurements were taken. The researchers noted that the observed discrepancies in readings due to arm position were substantial enough to influence whether a patient met the diagnostic threshold for hypertension.

According to the NHS, normal blood pressure is between 90/60 mmHg and 120/80 mmHg. High blood pressure is generally considered to be above 135/85 mmHg when measured at home, and 140/90 mmHg or higher when measured by a healthcare professional.

The American Heart Association has also updated its guidance, placing greater emphasis on accurate blood pressure measurement, particularly for home monitoring.

This concern about accurate diagnosis is echoed by separate analysis from the University of Oxford, which suggested that more than half of individuals with high blood pressure are unaware of their condition, increasing their risk of premature death. The Oxford researchers also estimated that only about half of those being treated for hypertension have their blood pressure adequately controlled.

Authors of the Oxford analysis argued that current guidelines may mean many cases of high blood pressure are missed or inadequately managed, contributing to what they described as a "leaky cascade of care."