A UK study published Online First by The Lancet concludes that ambulatory blood pressure monitoring (repeated measurements out of the clinic throughout a 24-hour period) is the most cost-effective way for diagnosing hypertension. As a result of the study, England's National Institute for Health and Clinical Excellence (NICE, which helped fund the study) is recommending ambulatory monitoring as best practice, as part of guidelines jointly devised with the British Society of Hypertension. The Article is written by Professor Richard J McManus and Dr Sue Jowett, University of Birmingham, UK, and colleagues.
Ambulatory blood pressure measurement consists of wearing a blood pressure cuff attached to an automatic blood pressure machine for a 24 hour period during which measurements are taken typically half hourly during the day and hourly over night. Because blood pressure varies during the day with a person's different activities, this allows a more comprehensive picture of an individual's blood pressure. Long term studies have shown that the average blood pressure over a 24 hour period is a better predictor of long term outcome (cardiovascular events) than blood pressure measured during a standard clinic appointment.
Most specialist units and some general practices (in the UK) already offer ambulatory blood pressure recordings which are fairly straightforward to undertake. An individual is fitted with a monitor one day, wears it for 24 hours and then brings it back the following day for the recording to be downloaded onto a computer and an automatic report generated. This new study assumes that an ambulatory recording is arranged after an initial high reading in the clinic to confirm whether or not an individual really has high blood pressure. About one person out of four with a raised reading in clinic will not have a raised ambulatory recording.
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. In this study, the authors modelled the cost-effectiveness of the 3 strategies.
The researchers found that 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 in men aged 75 years to –£323 in women aged 40 years) and resulted in small but significant improvements in quality of life. The authors say that diagnosis using ambulatory readings after an initially high clinic reading will confirm genuine cases of hypertension, and prevent treatment of patients whose ambulatory readings suggest their blood pressure is normal and that the high initial reading was due to the well-known white-coat effect (nervousness in a clinical setting) or other factors.
The authors conclude: "We have identified that ambulatory monitoring is the most cost-effective diagnostic strategy for confirming the diagnosis of hypertension across a range of age subgroups in both men and women. In most subgroups, we identified that ambulatory monitoring both improved health, increased quality of life, and reduced costs. Ambulatory monitoring for most people before the start of antihypertensive treatment should be seriously considered."
Professor McManus adds*: "Ambulatory monitoring allows better targeting of blood pressure treatment to those who will receive most benefit. It is already undertaken in some general practices and whilst implementation on a wide scale will need to be phased in to allow training and acquisition of new equipment, it is cost saving in the long term as well as more effective and so will be good for patients and doctors alike."
In a linked Comment, Dr Thomas A Gaziano, Brigham and Women's Hospital, Cardiovascular Division, Boston, MA, USA, says: "The cost savings are not surprising if the additional cost for ambulatory monitoring compared with clinic diagnosis is small, and if ambulatory monitoring leads to improved detection and treatment in people at highest risk. Improved diagnosis by both home and ambulatory monitoring results in reduction of morbid or fatal, as well as expensive, events attributable to cardiovascular disease, and minimises treatment of people who otherwise would be incorrectly labelled hypertensive."
For Professor Richard J McManus and Dr Sue Jovett, University of Birmingham, UK, please contact Jenni Ameghino T) +44 (0) 121 415 8134 / +44 (0) 7768 924156 E) r.j.mcmanus@bham.ac.uk
Dr Thomas A Gaziano, Brigham and Women's Hospital, Cardiovascular Division, Boston, MA, USA. T) +1 617 676-8178 E) tgaziano@partners.org
Note to editors: *quote direct from Prof McManus, not found in text of Article
The NICE press briefing to launch the clinical guideline on hypertension will take place on Tuesday 23 August at 10.00am, at the NICE offices in Holborn, central London:
The National Institute for Health and Clinical Excellence (NICE), MidCity Place, 71 High Holborn London, WC1V 6NA, A map is available on the NICE website at: http://www.nice.org.uk/page.aspx?o=contact
NICE press office: T) +44 (0) 845 003 7782, out of hours +44 (0) 7775 583 813 E) pressoffice@nice.org.uk
Journal
The Lancet