Unattended versus two attended, ambulatory and central blood pressure measurements in hypertensive patients with and without diabetes

OBJECTIVE: To compare unattended blood pressure (BP) with two attended BP, with 24-h ambulatory (ABPM) and central BP measurements in hypertensive patients with (DMs) and without diabetes (HTs). METHODS: In the same hypertension clinic we evaluate 129 consecutive HTs (56% female, 59 + 16 yrs) and 91 DMs (62% female, 64 + 9 yrs) who were referred for 24-h ABPM. During 48 hours they underwent a first attended BP (5 minutes resting, 3 recordings 2 minutes apart), (AT1), an unattended BP (UnAT), 3 measurements 2 minutes apart with a pre-programmed oscillometric Omron M10- IT, a second attended BP (AT2) similar to AT1, a 24-h ABPM and an evaluation of central BP (C) from the aortic wave form (SpygmoCor). RESULTS: BP (mm Hg) and differences (Δ) from UnAT = 135/82 ± 17/10 were 1AT = +13.8/3.9 ± 10.3/5.6, AT2 = +7.3/2.9 ± 7.4/4.9, 24-h = -1.3/-1.7 ± 7.5/7.5 and C = -2.4/1.2 ± 10.3/9.1, all p < .01 vs UnAT. Limits of agreement (2 SDs in Bland-Altman plots) were between AT1 and UnAT systolic BP, +34.2 to -6.8 mm Hg and between AT2 and UnAT BP were +21.7 to -7.0 mm Hg. Unattended systolic BP values were similar to that of 24-h in HTs and to that of daytime in DMs. Intraclass correlation coefficients of systolic BP and diastolic BP between UnAT and AT1 and between UnAT and AT2 were within the range 0.78 to 0.83, all p < .01. CONCLUSIONS: In HTs with and without DM the unattended BP significantly underestimates attended BP being more close to ambulatory BP values. These differences should be taken into account since targets based on these BP measurements are not equivalent.