Letters

Comparison of different measures of blood pressure

BMJ 2002; 325 doi: https://doi.org/10.1136/bmj.325.7376.1360 (Published 07 December 2002) Cite this as: BMJ 2002;325:1360

Use sphygmomanometers more, not less

  1. William T Hamilton (w.t.hamilton@btopenworld.com), research fellow,
  2. Deborah Sharp, professor
  1. Division of Primary Care, University of Bristol, Bristol BS6 6JL
  2. Birmingham University, Birmingham B15 2TT
  3. Department of Clinical and Experimental Medicine, University of Padua, Via Giustiniani, 2, I-35128-Padua, Italy
  4. General Practice Stiphout, Kloosterstraat 23a, NL-5708 GM Helmond, Netherlands
  5. Clinical Investigation Centre 9201, Assistance Publique des Hopitaux de Paris/INSERM, Hopital Européen Georges Pompidou, 75908 Paris Cedex 15, France

    EDITOR—Little et al in their study have shown that doctors' measurements of blood pressure are much higher than those taken by nurses, by the patient at home, or by ambulatory monitoring.1 From this they conclude that conventional measurements by general practitioners may be misleading in guiding treatment decisions. We believe, however, that this conclusion runs ahead of the evidence.

    The chain of research evidence that is required to make this conclusion has three links. The first link is finding a reliable method of measuring blood pressure; the second link is showing that raised blood pressure diagnosed by the chosen method increases the patient's risk of a cardiovascular event; the last link is showing that treatment reduces the risk. Knowing the absolute benefits of treatment and what target blood pressure to aim for are valuable parts of the last link.

    Our concern is that the research evidence for treatment decisions based on newer methods is not available for the last link. We know from well conducted trials that treatment based on clinic readings reduces risk. 2 3 Additionally, these trials have given us evidence to support a target for treatment. This evidence is much weaker for newer methods of diagnosing and monitoring hypertension. In essence we have two different diagnoses: hypertension diagnosed conventionally and hypertension diagnosed otherwise. The epidemiology of hypertension diagnosed otherwise is currently much less understood.

    Why are doctors' measurements higher than the other methods? The study did not address this but it is also important in extrapolating from the results of Little et al. One possibility is that the stakes are higher for the patient in a consultation with a doctor. This is presumably because the doctor has the power to label the patient with a diagnosis and to suggest and prescribe treatment. If we assume that …

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