BMJ  2005;331:466-467 (3 September), doi:10.1136/bmj.331.7515.466

Editorial

Self monitoring of high blood pressure

Doing it in the practice's waiting room may be better than doing it at home

Lowering raised blood pressure reduces patients' risk of developing cardiovascular disease.^{1 2} But the control of hypertension is often suboptimal, and this is borne out by the poorer effectiveness of treatment in observational studies than in randomised clinical trials.³ A recent systematic review by Fahey and colleagues emphasised that effective care for people with hypertension requires rigorous management with regular review and willingness to intensify drug treatment.⁴

The outcome of regular care depends on patients as much as, or more than, it does on practitioners. Evidence on managing chronic diseases such as diabetes mellitus and asthma emphasises the value of patients' participation, and the same is probably true for self monitoring of blood pressure. Measuring blood pressure is straightforward and has become even more so with the development of validated electronic measuring devices, which are now available to the public.⁵ Self monitoring satisfies the public's demand for more self control and knowledge about health and disease. In addition, it may affect workload in primary care.

A randomised controlled trial by McManus and colleagues in this issue (p 493) reports on self monitoring of blood pressure in the patient's general practice rather than at home.⁶ Practice based self monitoring of blood pressure is an original concept and is worth testing. The self measured and professionally measured blood pressure values were comparable, suggesting that hypertension guidelines, which will be based for the foreseeable future on professional measurement data, are applicable to self monitoring. In this study self monitoring resulted in a cost effective reduction in blood pressure, with no increase in patients' anxiety.

This new study provides valuable empirical data in line with earlier studies showing that home monitoring is more effective than usual care in controlling blood pressure and achieving targets.⁷ This effect is probably explained by the absence of a white coat effect and better adherence to treatment through self control. Despite these promising findings, some important questions remain unresolved.

Even though small gains in blood pressure reduction provided by self monitoring are clinically relevant, it is crucial to know whether they can be sustained over time, given the chronic nature of hypertension. If adherence to home monitoring declines over time it could lead to even poorer control of blood pressure through diminished contact between patients and doctors.⁸ Yet the average follow-up in all but a few studies of self monitoring has been less than a year.⁷

A weakness in the study by McManus and colleagues was the absence of cluster randomisation. As a consequence, general practitioners may have optimised their measurement during usual care, diminishing the effect size. Furthermore, systematic reviews show that most studies have been marred by methodological problems and have included only a small part of the hypertensive population in general practice.^{4 7} Self selection by enthusiastic participants in these studies may partly explain effectiveness, and this makes it difficult to recommend self measurement to all patients.⁹

Self monitoring of blood pressure should be part of a plan that includes patients more fully in decisions over treatment; includes regular checks of patients' blood pressure measurement technique; and provides some form of regular professional supervision. The hypertensive population in general practice is heterogeneous—for example, in terms of age, comorbidity, and individual preferences.¹⁰ That many patients declined the offer to join the self measurement group in the study by McManus and colleagues hampered recognitions of this heterogeneity. A practical solution could be to offer self monitoring only to those most likely to practise it, probably minimising the risk of anxiety and other adverse effects among patients. Testing patients' motivation and allocating a treatment strategy accordingly, along the lines of the stages of change model used in risk factor management, could facilitate selection.¹¹

Given that the current value of self monitoring of blood pressure remains uncertain, we recommend carefully designed experiments within the broader context suggested in the Cochrane review by Fahey and colleagues.⁴ Consultation at the practice at least once a year seems necessary to check whether the conditions for successful self measurement of blood pressure are still in place. But practice based self monitoring, as introduced by McManus and colleagues, offers a greater safety net. It allows active participation by patients without losing professional supervision, which may prove to be a considerable advantage over self monitoring at home.

(c.bakx{at}hag.umcn.nl)

Department of General Practice, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, Netherlands

---

Primary care p 493

References

1. Williams B, Poulter NR, Brown MJ, Davis M, McInnes GT, Potter JF, et al. Guidelines for management of hypertension: report of the fourth working party of the British Hypertension Society, 2004-BHS IV. J Hum Hypertens 2004;18: 139-85.[CrossRef][ISI][Medline]
2. Collins R, Peto R, MacMahon S, Hebert P, Fiebach NH, Eberlein KA, et al. Blood pressure, stroke, and coronary heart disease. Part 2. Short-term reductions in blood pressure: overview of randomised drug trials in their epidemiological context. Lancet 1990;335: 827-38.[CrossRef][ISI][Medline]
3. Wolf-Maier K, Cooper RS, Kramer H, Banegas JR, Giampaoli S, Joffres MR, et al. Hypertension treatment and control in five European countries, Canada, and the United States. Hypertension 2004;43: 10-7.[Abstract/Free Full Text]
4. Fahey T, Schroeder K, Ebrahim S. Interventions used to improve control of blood pressure in patients with hypertension. Cochrane Database Syst Rev 2003; CD005182.
5. O'Brien E, Asmar R, Beilin L, Imai Y, Mancia G, Mengden T, et al. Practice guidelines of the European Society of Hypertension for clinic, ambulatory and self blood pressure measurement. J Hypertens 2005;23: 697-701.[ISI][Medline]
6. McManus RJ, Mant J, Roalfe A, Oakes RA, Bryan S, Pattison HM, et al. Targets and self monitoring in hypertension: randomised controlled trial and cost effectiveness analysis. BMJ 2005;331: 493-6.[Abstract/Free Full Text]
7. Cappuccio FP, Kerry SM, Forbes L, Donald A. Blood pressure control by home monitoring: meta-analysis of randomised trials. BMJ 2004;329: 145.[Abstract/Free Full Text]
8. Staessen JA, Den Hond E, Celis H, Fagard R, Keary L, Vandenhoven G, et al. Antihypertensive treatment based on blood pressure measurement at home or in the physician's office: a randomized controlled trial. JAMA 2004;291: 955-64.[Abstract/Free Full Text]
9. Campbell NC,.Murchie P. Treating hypertension with guidelines in general practice. BMJ 2004;329: 523-4.[Free Full Text]
10. Little P, Barnett J, Barnsley L, Marjoram J, Fitzgerald-Barron A, Mant D. Comparison of acceptability of and preferences for different methods of measuring blood pressure in primary care. BMJ 2002;325: 258-9.[Free Full Text]
11. Verheijden MW, Bakx JC, Delemarre IC, Wanders AJ, van Woudenbergh NM, Bottema BJ, et al. GPs' assessment of patients' readiness to change diet, activity and smoking. Br J Gen Pract 2005;55: 452-7.[Medline]

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

Relevant Articles

Targets and self monitoring in hypertension: randomised controlled trial and cost effectiveness analysis

R J McManus, J Mant, A Roalfe, R A Oakes, S Bryan, H M Pattison, and F D R Hobbs
BMJ 2005 331: 493. [Abstract] [Full Text] [PDF]

Treating hypertension with guidelines in general practice

Neil C Campbell and Peter Murchie
BMJ 2004 329: 523-524. [Extract] [Full Text] [PDF]

Blood pressure control by home monitoring: meta-analysis of randomised trials

Francesco P Cappuccio, Sally M Kerry, Lindsay Forbes, and Anna Donald
BMJ 2004 329: 145. [Abstract] [Full Text] [PDF]

Comparison of acceptability of and preferences for different methods of measuring blood pressure in primary care

Paul Little, Jane Barnett, Lucy Barnsley, Jean Marjoram, Alex Fitzgerald-Barron, and David Mant
BMJ 2002 325: 258-259. [Full Text] [PDF]

Rapid Responses:

Read all Rapid Responses

BP Self-monitoring: Beware of the pitfalls!

William CW Wong, et al.
bmj.com, 5 Sep 2005 [Full text]

RCTs are not always the "gold standard"

Kath H Checkland
bmj.com, 4 Oct 2005 [Full text]

Applauding one Woman's Rebellion against Quetelet

Peter Morrell
bmj.com, 15 Oct 2005 [Full text]