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Clinical Review Evidence based treatment of hypertension

Measurement of blood presssure: an evidence based review

BMJ 2001; 322 doi: (Published 14 April 2001) Cite this as: BMJ 2001;322:908
  1. Finlay A McAlister, assistant professora (,
  2. Sharon E Straus, assistant professorb
  1. a Division of General Internal Medicine, University of Alberta, Edmonton, Canada T6G 2R7
  2. b Division of General Internal Medicine, Mount Sinai Hospital, Toronto, Canada M5G 1X5
  1. Correspondence to: F A McAlister

    This is the first in a series of five articles on the treatment of hypertension

    The reasons for routinely measuring blood pressures in adults are evident. Raised blood pressure is a common condition that does not have specific clinical manifestations until target organ damage develops. It confers a substantial risk of cardiovascular disease (particularly in the presence of concomitant risk factors), much of which is at least partially reversible with treatment. Finally, screening adults to detect hypertension early and initiate treatment before the onset of target organ damage is highly cost effective.1

    Accurate measurement is of paramount importance. For example, consistently underestimating the diastolic pressure by 5 mm Hg could result in almost two thirds of hypertensive individuals being denied potentially lifesaving—and certainly morbidity preventing—treatment2; consistently overestimating it by 5 mm Hg could more than double the number of individuals diagnosed as hypertensive (half of whom would be inappropriately labelled and treated).2

    Summary points

    The accurate measurement of blood pressure in clinic settings is of paramount importance

    Guidelines for its measurement should be followed, particularly when it is newly detected or the patient has cardiovascular target organ damage, other atherosclerotic risk factors, or is receiving antihypertensive treatment

    Evidence regarding factors which distort blood pressure readings and the magnitude of their effect is generally weak, but factors shown in high quality studies to be able to affect readings by more than 5 mm Hg include talking, acute exposure to cold, recent ingestion of alcohol, incorrect arm position, and incorrect cuff size

    The white coat effect can raise blood pressure more than 20/10 mm Hg in up to 40% of patients

    The benefits and cost effectiveness of self measurement or ambulatory monitoring are still under investigation, but they should be considered for the evaluation of suspected white coat hypertension, apparent …

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