Inter arm blood pressure difference

Inter arm blood pressure difference

Guidelines on hypertension generally recommend measurement of blood pressure in both arms in the initial visit. They also suggest that the arm with higher blood pressure recording should be used to record blood pressure in subsequent visits [1]. It is often mentioned that there is a small difference in the blood pressure between the arms and usually it is the right arm blood pressure which is higher.

But some authors have suggested that clinically meaningful interarm differences in blood pressure are not reproducible in the absence of obstructive arterial disease. They attributed the differences in those without obstructive arterial disease to random error [2]. Still, their study also documented slightly higher blood pressure in the right arm, 2-3 mm Hg for systolic blood pressure and 1 mm Hg for diastolic blood pressure.

Prognostic significance of inter arm blood pressure difference has been evaluated in studies. One study evaluated 421 consecutive patients from medical and renal wards [3]. They were followed up for all-cause mortality up to 7 years. Right arm systolic blood pressure was 5.1 mm Hg higher, but the difference came down to 2.2 mm Hg after a week. At the same time, systolic blood pressure dropped 6.9 mm Hg over one week and an extra 5.3 mm Hg in those with chronic kidney disease. The crude mortality rate in the study was 6.33 per 100 patient-years. Every 10 mm Hg difference in systolic blood pressure between the arms was found to confer a higher mortality hazard of 24%, after adjusting for average systolic blood pressure and chronic kidney disease. Overall, about 30% of patients had inter-arm blood pressure difference more than 10 mm Hg.

Another study of 610 patients noted that 53% of patients had a systolic or diastolic inter arm blood pressure difference of more than 10 mm Hg and 19% had the difference above 20 mm Hg [4]. Authors mentioned that large interarm blood pressure difference was assumed to help identify patients with aortic dissection. But their study was on a convenience sample of ambulatory patients who were seen at a university hospital emergency department.

A simple random sample of 1634 patients showed that 26.2% were at moderate risk of vascular events with inter arm systolic blood pressure difference between 10-15 mm Hg [5]. 17.3% were at high risk of vascular events with inter arm systolic blood pressure difference of more than 15 mm Hg. In case of diastolic blood pressure, 14.2% had inter arm difference of 10-15 mm Hg and 6.1% had it above 15 mm Hg. They found a statistically significant association between inter arm systolic blood pressure difference and hypertension, smoking and alcoholism. In case of diastolic blood pressure, the association was with overweight/obesity.

If significant inter arm blood pressure difference is due to peripheral vascular disease, they are at higher risk for cardiovascular or cerebrovascular events [6]. 13.6% of a group of 280 patients had inter arm systolic blood pressure difference of 20 mm Hg or more. 23.2% had diastolic blood pressure difference of 10 mm Hg or more. 83 patients were followed up for 5.6 years. Patients with diastolic blood pressure difference of 10 mm Hg or more had a mean event free survival of 3.3 years compared with 5 years for those with diastolic blood pressure difference less than 10 mm Hg. Those with systolic blood pressure difference of 20 mm Hg or more had a mean event free survival of 3.5 years, compared with 4.9 years for those with systolic blood pressure difference less than 20 mm Hg. An association between inter arm blood pressure difference and increased morbidity and mortality was found in that study.

References

1. Whelton PK, Carey RM, Aronow WS, Casey DE Jr, Collins KJ, Dennison Himmelfarb C, DePalma SM, Gidding S, Jamerson KA, Jones DW, MacLaughlin EJ, Muntner P, Ovbiagele B, Smith SC Jr, Spencer CC, Stafford RS, Taler SJ, Thomas RJ, Williams KA Sr, Williamson JD, Wright JT Jr. 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: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension. 2018 Jun;71(6):e13-e115. doi: 10.1161/HYP.0000000000000065. Epub 2017 Nov 13. Erratum in: Hypertension. 2018 Jun;71(6):e140-e144. PMID: 29133356.
2. Eguchi K, Yacoub M, Jhalani J, Gerin W, Schwartz JE, Pickering TG. Consistency of blood pressure differences between the left and right arms. Arch Intern Med. 2007 Feb 26;167(4):388-93. doi: 10.1001/archinte.167.4.388. PMID: 17325301.
3. Agarwal R, Bunaye Z, Bekele DM. Prognostic significance of between-arm blood pressure differences. Hypertension. 2008 Mar;51(3):657-62. doi: 10.1161/HYPERTENSIONAHA.107.104943. Epub 2008 Jan 22. PMID: 18212263.
4. Singer AJ, Hollander JE. Blood pressure. Assessment of interarm differences. Arch Intern Med. 1996 Sep 23;156(17):2005-8. doi: 10.1001/archinte.156.17.2005. PMID: 8823153.
5. Gopalakrishnan S, Savitha AK, Rama R. Evaluation of inter-arm difference in blood pressure as predictor of vascular diseases among urban adults in Kancheepuram District of Tamil Nadu. J Family Med Prim Care. 2018 Jan-Feb;7(1):142-146. doi: 10.4103/jfmpc.jfmpc_62_17. PMID: 29915748; PMCID: PMC5958556.
6. Clark CE, Powell RJ. The differential blood pressure sign in general practice: prevalence and prognostic value. Fam Pract. 2002 Oct;19(5):439-41. doi: 10.1093/fampra/19.5.439. PMID: 12356690.