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Isolated increases in in-office pressure account for a significant proportion of nurse-derived blood pressure-target organ relations

Maseko, Muzi J.*; Woodiwiss, Angela J.*; Majane, Olebogeng H.I.; Libhaber, Carlos D.; Brooksbank, Richard; Norton, Gavin R.*

doi: 10.1097/HJH.0b013e32836123ca
ORIGINAL PAPERS: BP measurement

Aims: We determined the extent to which relationships between nurse-derived blood pressures (BPs) and cardiovascular damage may be attributed to isolated increases in in-office SBP independent of ambulatory BP.

Methods: In 750 participants from a community sample, nurse-derived office BP, ambulatory BP, carotid-femoral pulse wave velocity (PWV; applanation tonometry and SphygmoCor software; n = 662), and left ventricular mass indexed to height2.7 (LVMI; echocardiography; n = 463) were determined.

Results: Nurse-derived office BP was associated with organ changes independent of 24-h BP (LVMI; partial r = 0.15, P <0.005, PWV; partial r = 0.21, P <0.0001) and day BP. However, in both unadjusted (P < 0.0001 for both) and multivariate adjusted models (including adjustments for 24-h BP; LVMI; partial r = 0.14, P <0.01, PWV; partial r = 0.21, P <0.0001), nurse office-day SBP (an index of isolated increases in in-office BP) was associated with target organ changes independent of ambulatory BP and additional confounders, with the highest quartile (≥15 mmHg) showing the most marked increases in LVMI (P <0.0005) and PWV (P <0.0001) as compared to the lowest quartile (<−5 mmHg). These relationships were reproduced in those with normotensive day BP values and the quantitative effect of nurse office-day BP on target organ changes was at least equivalent to that of ambulatory BP.

Conclusion: Nurse-elicited isolated increases in in-office BP account for a significant proportion of the relationship between nurse-derived BP and target organ changes independent of ambulatory BP. Therefore, high quality nurse-derived BP measurements do not approximate the impact of BP effects per se on cardiovascular damage.

Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa

*Muzi J. Maseko, Angela J. Woodiwiss, and Gavin R. Norton contributed equally to the writing of this work.

Correspondence to Angela J. Woodiwiss, Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, University of the Witwatersrand Medical School, 7 York Road, Parktown, 2193 Johannesburg, South Africa. Tel: +27 11 717 2363; fax: +27 11 717 2153; e-mail: gavin.norton@wits.ac.za/angela.woodiwiss@wits.ac.za

Abbreviations: ABP, ambulatory blood pressure; BP, blood pressure; Echo, echocardiography; HbA1c, glycated hemoglobin; HDL, high-density lipoprotein; LVMI, left ventricular mass indexed to height2.7; PWV, pulse wave velocity

Received 15 January, 2013

Revised 25 February, 2013

Accepted 12 March, 2013

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© 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins