Elsevier

The Lancet

Volume 378, Issue 9798, 1–7 October 2011, Pages 1219-1230
The Lancet

Articles
Cost-effectiveness of options for the diagnosis of high blood pressure in primary care: a modelling study

https://doi.org/10.1016/S0140-6736(11)61184-7Get rights and content

Summary

Background

The diagnosis of hypertension has traditionally been based on blood-pressure measurements in the clinic, but home and ambulatory measurements better correlate with cardiovascular outcome, and ambulatory monitoring is more accurate than both clinic and home monitoring in diagnosing hypertension. We aimed to compare the cost-effectiveness of different diagnostic strategies for hypertension.

Methods

We did a Markov model-based probabilistic cost-effectiveness analysis. We used a hypothetical primary-care population aged 40 years or older with a screening blood-pressure measurement greater than 140/90 mm Hg and risk-factor prevalence equivalent to the general population. We compared three diagnostic strategies—further blood pressure measurement in the clinic, at home, and with an ambulatory monitor—in terms of lifetime costs, quality-adjusted life years, and cost-effectiveness.

Findings

Ambulatory monitoring was the most cost-effective strategy for the diagnosis of hypertension for men and women of all ages. It was cost-saving for all groups (from −£56 [95% CI −105 to −10] in men aged 75 years to −£323 [−389 to −222] in women aged 40 years) and resulted in more quality-adjusted life years for men and women older than 50 years (from 0·006 [0·000 to 0·015] for women aged 60 years to 0·022 [0·012 to 0·035] for men aged 70 years). This finding was robust when assessed with a wide range of deterministic sensitivity analyses around the base case, but was sensitive if home monitoring was judged to have equal test performance to ambulatory monitoring or if treatment was judged effective irrespective of whether an individual was hypertensive.

Interpretation

Ambulatory monitoring as a diagnostic strategy for hypertension after an initial raised reading in the clinic would reduce misdiagnosis and save costs. Additional costs from ambulatory monitoring are counterbalanced by cost savings from better targeted treatment. Ambulatory monitoring is recommended for most patients before the start of antihypertensive drugs.

Funding

National Institute for Health Research and the National Institute for Health and Clinical Excellence.

Introduction

High blood pressure is a key risk factor for the development of cardiovascular disease,1 and a major cause of morbidity and mortality worldwide.2 Hypertension is the most common reason for a primary-care consultation for a chronic disorder, and at least 25% of adults are hypertensive.3, 4

The diagnosis of hypertension has traditionally been based on several blood-pressure measurements made in the clinic, which are typically undertaken after a raised initial reading.5, 6, 7, 8, 9 Ambulatory blood-pressure monitoring better correlates with cardiovascular outcome10, 11, 12 than does clinic blood pressure, and it is used where there is uncertainty in diagnosis, resistance to treatment, irregular or diurnal variation, or concerns about variability and the so-called white-coat effect.13, 14, 15 Therefore, ambulatory monitoring is arguably the de facto reference standard for the diagnosis of hypertension. Moreover, recent analyses suggest that ambulatory monitoring is more accurate than both monitoring in the clinic and the home in defining the presence of hypertension and could therefore form part of the diagnostic pathway.16

Home blood-pressure monitoring, which provides many readings over several days, also better correlates with end-organ damage than measurement in the clinic.17, 18 Monitoring in the home seems a better prognostic indicator with respect to stroke and cardiovascular mortality than monitoring in the clinic and can detect the white-coat effect and masked hypertension.19, 20, 21 Although monitoring at home has a smaller evidence base, it might provide an appropriate alternative to ambulatory monitoring in terms of diagnosis, particularly in primary care where ambulatory monitoring is not always immediately available or when patients find it inconvenient or uncomfortable.

The use of out-of-office measurements in the initial screening of patients for hypertension is currently unsupported by evidence, hence it is probable that they would be undertaken after an raised initial reading in the clinic. Such a shift in practice would require substantial investment in new devices, especially in primary care, and it is unclear if this would be cost effective. Our aim was therefore to develop a model to assess the cost-effectiveness of three diagnostic strategies for hypertension after a raised initial clinic blood-pressure reading: further blood-pressure measurement in the clinic, at home, or with an ambulatory monitor.

Section snippets

Procedure

We did a cost-effectiveness analysis comparing blood-pressure monitoring in the clinic (measurements at monthly intervals over 3 months), in the home (measurements over a week), or ambulatory monitoring (measurements over 24 h). We expressed our findings in terms of costs, quality-adjusted life years (QALYs), and incremental costs per QALY gained. In the UK, an incremental cost-effectiveness ratio of less than £20 000–30 000 is generally thought cost effective by policy makers.22

In brief, we

Results

In our base-case analysis, ambulatory monitoring was the most cost-effective strategy for men and women of all ages. It was cost-saving in all groups and resulted in improved health outcomes for male and female age-groups older than 50 years (table 3). Consequently, ambulatory monitoring was the dominant strategy for men and women of most ages. For example, the base case results for a man aged 60 years showed that, compared with diagnosis by clinic monitoring, diagnosis by home monitoring

Discussion

Our findings show that ambulatory monitoring is cost effective compared with further monitoring in the clinic or home for confirming the diagnosis of hypertension in a population with suspected blood pressure greater than 140/90 mm Hg on the basis of a clinic screening measurement. Our conclusion is consistent across all age-stratified and sex-stratified subgroups we considered and is robust when assessed with a wide range of sensitivity analyses. The only exception was if home monitoring was

References (62)

  • The seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure—complete report

  • Hypertension: management in adults in primary care: pharmacological update

    (2006)
  • G Mancia et al.

    2007 Guidelines for the Management of Arterial Hypertension: The Task Force for the Management of Arterial Hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC)

    J Hypertens

    (2007)
  • T Ohkubo et al.

    Prediction of stroke by ambulatory blood pressure monitoring versus screening blood pressure measurements in a general population: the Ohasama study

    J Hypertens

    (2000)
  • JA Staessen et al.

    Predicting cardiovascular risk using conventional vs ambulatory blood pressure in older patients with systolic hypertension

    JAMA

    (1999)
  • Y Imai et al.

    Predictive power of screening blood pressure, ambulatory blood pressure and blood pressure measured at home for overall and cardiovascular mortality: a prospective observation in a cohort from Ohasama, northern Japan

    Blood Press Monit

    (1996)
  • JA Whitworth

    2003 World Health Organization (WHO)/International Society of Hypertension (ISH) statement on management of hypertension

    J Hypertens

    (2003)
  • P Verdecchia

    Reference values for ambulatory blood pressure and self-measured blood pressure based on prospective outcome data

    Blood Press Monit

    (2001)
  • J Redon et al.

    Prognostic value of ambulatory blood pressure monitoring in refractory hypertension: a prospective study

    Hypertension

    (1998)
  • J Hodgkinson et al.

    Relative effectiveness of clinic and home blood pressure monitoring compared with ambulatory blood pressure monitoring in diagnosis of hypertension: systematic review

    BMJ

    (2011)
  • G Mulè et al.

    Value of home blood pressures as predictor of target organ damage in mild arterial hypertension

    J Cardiovasc Risk

    (2002)
  • S Tsunoda et al.

    Relationship between home blood pressure and longitudinal changes in target organ damage in treated hypertensive patients

    Hypertens Res

    (2002)
  • T Ohkubo et al.

    Home blood pressure measurement has a stronger predictive power for mortality than does screening blood pressure measurement: a population-based observation in Ohasama, Japan

    J Hypertens

    (1998)
  • G Bobrie et al.

    Is “isolated home” hypertension as opposed to “isolated office” hypertension a sign of greater cardiovascular risk?

    Arch Intern Med

    (2001)
  • K Asayama et al.

    Use of 2003 European Society of Hypertension-European Society of Cardiology guidelines for predicting stroke using self-measured blood pressure at home: the Ohasama study

    Eur Heart J

    (2005)
  • Social value judgements: principles for the development of NICE guidance

    (2008)
  • Guide to the methods of technology appraisal

    (2009)
  • R Craig et al.

    Joint Health Surveys Unit: health survey for England 2006

    (2006)
  • Clinical guideline 127: hypertension (update)

  • P Little et al.

    Comparison of agreement between different measures of blood pressure in primary care and daytime ambulatory blood pressure

    BMJ

    (2002)
  • E Dolan et al.

    Superiority of ambulatory over clinic blood pressure measurement in predicting mortality: the Dublin outcome study

    Hypertension

    (2005)
  • Cited by (283)

    • The assessment of blood pressure in pregnant women: pitfalls and novel approaches

      2022, American Journal of Obstetrics and Gynecology
      Citation Excerpt :

      Ambulatory BP monitoring involves an individual wearing an ambulatory BP monitor, and BP is automatically measured at repeated intervals through day and night.40 It is recommended as the definitive test for diagnosing chronic hypertension (outside of pregnancy) in the United States, Canada, and the United Kingdom,41 because there is evidence of clinical and cost effectiveness.42–44 However, home BP monitoring may be favored over ambulatory BP monitoring owing to the ease of use with increased availability and lower cost.

    View all citing articles on Scopus
    View full text