BACKGROUND: When blood pressure (BP) is taken for the first time, it should be measured in both arms; follow-up measurements should be taken in the arm with the highest BP. However, in clinical practice, this recommendation is rarely followed. OBJECTIVE: Identify the degree of differences in BP between the right and the left arm in individuals with normal and high BP. METHODS: We measured BP in 111 hypertensive and 80 normotensive patients in both arms at the same time using identical Omron HEM 725 CIC automatic sphygmomanometers. The devices were then switched to the other arm and another set of readings was taken. The absolute and relative difference in BP between arms was calculated from the average of these two readings. We categorized differences as at least 5, at least 10, and at least 20 mmHg for systolic blood pressure/diastolic blood pressure (SBP/DBP). RESULTS: The BP was higher in the right arm, with no statistical significance. The relative differences were also not significant: SBP 1.1±7.1 and DBP 0.21±5.0. However, the absolute differences were significant at an individual level, with a systolic difference of 5.4±4.8 mmHg and a diastolic difference of 3.9 ±3.2 mmHg. The percentages of absolute SBP/DBP differences more than 5 mmHg (21.4%/20.4%) and more than 10 mmHg (15.7%/4.7%) were considerable. The range of arm differences was clinically significant; in hypertensives, the SBP/DBP was -13.2 to +15/-9.2 to +9.6 mmHg and in nonhypertensives it was -12.9 to +15.6/-9.7 to +10.1 mmHg. CONCLUSION: Although on average there was no clinically significant relative difference between arms, absolute differences at an individual level were often clinically significant. Failure to determine interarm BP differences will lead to erroneous clinical decisions.
BACKGROUND: When blood pressure (BP) is taken for the first time, it should be measured in both arms; follow-up measurements should be taken in the arm with the highest BP. However, in clinical practice, this recommendation is rarely followed. OBJECTIVE: Identify the degree of differences in BP between the right and the left arm in individuals with normal and high BP. METHODS: We measured BP in 111 hypertensive and 80 normotensive patients in both arms at the same time using identical Omron HEM 725 CIC automatic sphygmomanometers. The devices were then switched to the other arm and another set of readings was taken. The absolute and relative difference in BP between arms was calculated from the average of these two readings. We categorized differences as at least 5, at least 10, and at least 20 mmHg for systolic blood pressure/diastolic blood pressure (SBP/DBP). RESULTS: The BP was higher in the right arm, with no statistical significance. The relative differences were also not significant: SBP 1.1±7.1 and DBP 0.21±5.0. However, the absolute differences were significant at an individual level, with a systolic difference of 5.4±4.8 mmHg and a diastolic difference of 3.9 ±3.2 mmHg. The percentages of absolute SBP/DBP differences more than 5 mmHg (21.4%/20.4%) and more than 10 mmHg (15.7%/4.7%) were considerable. The range of arm differences was clinically significant; in hypertensives, the SBP/DBP was -13.2 to +15/-9.2 to +9.6 mmHg and in nonhypertensives it was -12.9 to +15.6/-9.7 to +10.1 mmHg. CONCLUSION: Although on average there was no clinically significant relative difference between arms, absolute differences at an individual level were often clinically significant. Failure to determine interarm BP differences will lead to erroneous clinical decisions.