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Definition of ambulatory blood pressure targets for diagnosis and treatment of hypertension in relation to clinic blood pressure: prospective cohort study

BMJ 2010; 340 doi: https://doi.org/10.1136/bmj.c1104 (Published 14 April 2010) Cite this as: BMJ 2010;340:c1104
  1. Geoffrey A Head, NHMRC principal research fellow and professor of pharmacology1,
  2. Anastasia S Mihailidou, senior hospital scientist and clinical senior lecturer2,
  3. Karen A Duggan, associate professor3,
  4. Lawrence J Beilin, Winthrop professor of medicine4,
  5. Narelle Berry, postdoctoral research fellow5,
  6. Mark A Brown, professor of renal medicine6,
  7. Alex J Bune, associate professor7,
  8. Diane Cowley, clinical nurse consultant8,
  9. John P Chalmers, senior director, the George Institute and emeritus professor of medicine9,
  10. Peter R C Howe, research professor5,
  11. Jonathan Hodgson, professor4,
  12. John Ludbrook, professorial fellow10,
  13. Arduino A Mangoni, associate professor of clinical pharmacology11,
  14. Barry P McGrath, professor of vascular medicine12,
  15. Mark R Nelson, professorial fellow 13,
  16. James E Sharman, senior research fellow1314,
  17. Michael Stowasser, Codirector8
  18. Ambulatory Blood Pressure Working Group of the High Blood Pressure Research Council of Australia
  1. 1Baker IDI Heart and Diabetes Institute, Melbourne, Victoria 8008, Australia
  2. 2Royal North Shore Hospital and University of Sydney, Sydney, Australia
  3. 3Sydney South West Area Health Service, Sydney
  4. 4School of Medicine and Pharmacology, University of Western Australia, Royal Perth Hospital, Perth, Australia
  5. 5Nutritional Physiology Research Centre, University of South Australia, Adelaide, Australia
  6. 6University of New South Wales, St George Hospital, Sydney
  7. 7University of Sydney, Royal Prince Alfred Hospital, Camperdown, Australia
  8. 8Hypertension Unit, Princess Alexandra Hospital, University of Queensland School of Medicine, Brisbane, Australia
  9. 9George Institute, University of Sydney, Sydney
  10. 10University of Melbourne, Parkville, Australia
  11. 11Department of Clinical Pharmacology, Flinders University, Adelaide
  12. 12Monash University, Centre for Vascular Health, Southern Health, Dandenong, Australia
  13. 13Menzies Research Institute, Hobart, Australia
  14. 14Endocrine Hypertension Research Centre, School of Medicine, University of Queensland, Brisbane, Australia
  1. Correspondence to: G A Head geoff.head{at}baker.edu.au
  • Accepted 18 January 2010

Abstract

Background Twenty-four hour ambulatory blood pressure thresholds have been defined for the diagnosis of mild hypertension but not for its treatment or for other blood pressure thresholds used in the diagnosis of moderate to severe hypertension. We aimed to derive age and sex related ambulatory blood pressure equivalents to clinic blood pressure thresholds for diagnosis and treatment of hypertension.

Methods We collated 24 hour ambulatory blood pressure data, recorded with validated devices, from 11 centres across six Australian states (n=8575). We used least product regression to assess the relation between these measurements and clinic blood pressure measured by trained staff and in a smaller cohort by doctors (n=1693).

Results Mean age of participants was 56 years (SD 15) with mean body mass index 28.9 (5.5) and mean clinic systolic/diastolic blood pressure 142/82 mm Hg (19/12); 4626 (54%) were women. Average clinic measurements by trained staff were 6/3 mm Hg higher than daytime ambulatory blood pressure and 10/5 mm Hg higher than 24 hour blood pressure, but 9/7 mm Hg lower than clinic values measured by doctors. Daytime ambulatory equivalents derived from trained staff clinic measurements were 4/3 mm Hg less than the 140/90 mm Hg clinic threshold (lower limit of grade 1 hypertension), 2/2 mm Hg less than the 130/80 mm Hg threshold (target upper limit for patients with associated conditions), and 1/1 mm Hg less than the 125/75 mm Hg threshold. Equivalents were 1/2 mm Hg lower for women and 3/1 mm Hg lower in older people compared with the combined group.

Conclusions Our study provides daytime ambulatory blood pressure thresholds that are slightly lower than equivalent clinic values. Clinic blood pressure measurements taken by doctors were considerably higher than those taken by trained staff and therefore gave inappropriate estimates of ambulatory thresholds. These results provide a framework for the diagnosis and management of hypertension using ambulatory blood pressure values.

Footnotes

  • This research is part of a joint initiative between the High Blood Pressure Research Council of Australia and the National Heart Foundation of Australia, which aims to support appropriate use and interpretation of ambulatory blood pressure monitoring and effective management of blood pressure in the primary care setting.

  • Contributors: GAH was involved in study conception and design, study supervision, statistical analysis, preparation of graphs and tables, data interpretation, and drafting, revision, and finalising of the paper. ASM and KAD were involved in study conception and design, study supervision, data interpretation and drafting, revision, and finalising of the paper. NB, MAB, DC, PRCH, JH, AAM, BPM, MRN, and JES and were involved in study supervision, data interpretation, and revision and finalising of the paper. LJB, AJB, MS, and JPC and were involved in data interpretation and revision and finalising of the paper. JL was the study statistician and was involved in data analysis, drafting and revision of the paper. GAH is the guarantor. All authors had full access to all the data (including statistical reports and tables) in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. We thank Kanella Chatzivlastou, Melinda Carrington, Carla M. Morley, Kim N Do, Karen Hall, Mark J Penny, Lai H Siew, and Agnes Ross for contributions to collection and analysis of data.

  • Funding: Financial sponsorship was supplied to the first author, GAH, for the analysis of the data from the High Blood Pressure Research Council of Australia. All authors are members of the council.

  • Competing interests: All authors have completed the Unified Competing Interest form, which is available on request from the corresponding author. The authors declare that (1) no authors have support from any company for the submitted work; (2) no authors have any relationships with companies that might have an interest in the submitted work in the previous 3 years; (3) their spouses, partners, or children have no financial relationships that may be relevant to the submitted work; and (4) no authors have non-financial interests that may be relevant to the submitted work.

  • Ethical approval: Ethics committee approval was not required because we used anonymised data.

  • Data sharing: no additional data available.

  • Accepted 18 January 2010

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