[Measuring blood pressure in the forearm of obese patients: concordance with arm measurement].

Background And Objective: The occasional forearm blood pressure (BP) measurement has been accepted for some obese patients. However, few studies have compared the concordance between arm and forearm BP measurements. Our aim was to know whether the forearm BP measurement displays a good concordance with the arm BP measurement in obese patients.

Subjects And Method: Cross-sectional descriptive study in an ambulatory setting. By means of convenience sampling, a sample of 54 patients with a body mass index > 26 kg/m2 was selected. The study unit was the upper limb (n = 108). BP was measured 3 times in each arm and forearm (12 measurements in each patient using an automated validated device OMRON 705CP) in a randomized order.

Results: Women: 77.8%; mean (SD) aged: 60.2 (12.7) years; body mass index: 38.6 (5.5) kg/m2; 79.6% were hypertensive. BP was higher in forearm than in arm: mean (SD) 137.7 (16.9) mmHg versus 132.1 (18) mmHg, for systolic (S) BP (p < 0.001) and 79.8 (11.2) mmHg versus 78.3 (9.9) mmHg for diastolic (D) BP (p = 0.04), respectively. Intraclass correlation coefficients for arm/forearm measurements were 0.83 (95% confidence interval [CI], 0.77-0.88) and 0.74 (95% CI, 0.65-0.82) for SBP and DBP, respectively. Mean differences between arm and forearm measurements were 5.5 mmHg (95% CI, -14.5 to 25.5) mmHg for SBP and 1.53 mmHg [95% CI, -13.5 to 16.5] for DBP.

Conclusions: BP differences between arm/forearm measurements are clinically outstanding. Therefore, forearm BP measurement does not seem advisable in obese patients.