Hypertension diagnosis based on automated office blood pressure and the use of confidence intervals

Journal of the American Society of Hypertension 10(4S) (2016) e19–e38

POSTER SESSION I BLOOD PRESSURE MEASUREMENT/MONITORING

ANTIHYPERTENSIVE DRUGS AND PHARMACOLOGY

P-1

P-2

Hypertension diagnosis based on automated office blood pressure and the use of confidence intervals Ignacio Alonso,2 Marıa M. Martinez,1 Teresa M. Dıaz.1 1 Sergas, Vigo, Spain; 2University of Vigo, Vigo, Spain

Inferior antihypertensive efficacy with low dose hydrochlorothiazide Chirag Bavishi,3 Franz H. Messerli,2 Anil K. Pareek,1 Saurav Chatterjee,3 Harikrishna Makani,5 Stefano Rimoldi,6 Sripal Bangalore.4 1 Ipca Laboratories Limited, Mumbai, India; 2Mount Sinai Medical Center, New York, NY, United States; 3Mount Sinai St. Luke’s & Roosevelt Hospitals, New York, NY, United States; 4New York University School of Medicine, New York, NY, United States; 5St. Mary Medical Center, Apple Valley, CA, United States; 6University Hospital, Bern, Switzerland

Herein we present a new algorithm for hypertension diagnosis based on Office Blood Pressure (OBP) readings which considers the inter-visit and intra-visit variability and provides a confidence interval (CI) of the patient’s BP. We assume the following statistical model for OBP: Pij¼OBP+Xi+Yij Where: Pij: jth BP reading on the ith visit. OBP: Blood pressure of the patient to be estimated. X and Y: Random variables which respectively measure the inter-visit and intra-visit variability; provided that they are Gaussian, zero mean and independent for every i and j, Pij is also Gaussian. In the herein proposed protocol, the average of a fixed number of OBP readings is calculated in every patient’s visit, so that after a number of visits the set of averages forms a simple random sample of a Gaussian distribution, and a CI for OBP can thus be calculated based on the t-Student distribution. This CI can then be compared with the usual thresholds for hypertension diagnosis. For example, a CI for SBP of (128, 132) and DBP of (75, 85) mmHg would indicate that hypertension is discarded. On the other hand values of (133, 148) mmHg for SBP would be indicative of an unreliable diagnosis and the need for more visits. Because the appropriate use of this model requires the use of stabilized OBP readings, Automated OBP (AOBP) is the preferred measuring technique: it allows more readings without consuming time of the clinical staff and diminishes the white-coat effect. We have found that with a pre-reading resting period of 5 min and subsequent 2.5 min intervals between measurements, AOBP readings become stabilized from the 4th reading onwards. Our recommendation is to get at least 6 AOBP readings on each visit and discard the first three. The proposed OBP model provides an effective way to deal with its high inter-visit and intra-visit variability. Moreover, the calculation of CI allows to determine the uncertainty of the OBP estimations and to evaluate if more visits of the patient are needed in order to get an accurate hypertension diagnosis. Support from the European Regional Development Fund (ERDF) and the Galician Government under the agreement for funding the Atlantic Research Center for Information and Communication Technologies (AtlantTIC) is gratefully acknowledged. Keywords: Office Blood Pressure; Automated Office Blood Pressure; Hypertension diagnosis; Confidence intervals

Hydrochlorthiazide (HCTZ) is one of the most commonly prescribed antihypertensive drugs worldwide. More than 97% of all HCTZ prescriptions are for 12.5 to 25 mg per day. The purpose of this study was to evaluate the antihypertensive efficacy of HCTZ by clinic blood pressure (BP) and ambulatory BP (ABP) monitoring when compared to other anti-hypertensives. A systematic review was performed using Medline, Cochrane, Scopus and Embase databases for all randomized trials that assessed both clinic and 24-h ABP with HCTZ in comparison with other antihypertensive drugs. In addition, trials were selected only if they studied HCTZ as monotherapy and have trial duration of at least 4 weeks. Eleven studies (16 comparisons) with 918 patients fulfilled the inclusion criteria. All the studies used HCTZ dose 12.5 to 25 mg/day except one study that used a dose of 25-50 mg/day. The decrease in clinic BP with HCTZ was systolic 12.1 mm Hg (95% confidence interval [CI]: 6.0 to 18.3 mm Hg) and diastolic 6.3 mm Hg (95% CI: 2.8 to 9.9 mm Hg). The reduction in 24-h ABP with HCTZ was systolic 6.4 mm Hg (95% CI: 5.0 to 7.7 mm Hg) and diastolic 3.3 mm Hg (95% CI: 1.8 to 4.9 mm Hg). In head-to-head comparisons with other antihypertensive drug classes, compared to HCTZ, ACE inhibitors/ARBs resulted in significant greater reduction in systolic clinic and ABP by 4.5/2.3 mm Hg, beta-blockers by 8.1/6.2 mm Hg, calcium antagonists by 3.2/2.5 mm Hg and thiazide-type diuretics by 7.8/5.3 mm Hg. Similarly, other anti-hypertensive drug classes resulted in significantly greater reduction of diastolic ABP and clinic DBP (trend). The incremental 24-h systolic ABP reduction over HCTZ by ACE inhibitors/ARBs was 63%, by beta-blockers was 75%, by calcium antagonists was 64% and thiazide-type diuretics was 122%. In conclusion, HCTZ resulted in an acceptable reduction in clinic systolic and diastolic BP, however when analyzed using 24-h ABP, the reduction in BP was modest at best. Moreover, the antihypertensive efficacy of 12.5 to 25 mg daily dose of HCTZ measured in head-to-head studies by clinic and ABP measurement was consistently inferior to that of all other drug classes. Keywords: Hydrochlorothiazide; Efficacy; Ambulatory Blood Pressure; Meta-analysis

Figure 1.

1933-1711/$ - see front matter Ó 2016 American Society of Hypertension. All rights reserved.