[Costs analysis of ambulatory blood pressure monitoring in mild hypertension]. / Análisis de costes de la monitorización ambulatoria de la presión arterial en hipertensión leve.

BACKGROUND: To contrast the costs of conventional and ambulatory blood pressure monitoring (ABPM) methods in the diagnosis, treatment and follow-up of mild hypertensive patients. METHODS: Among patients with conventional diagnosis of mild hypertension, the ABPM would discriminate patients with sustained hypertension, who would receive drug treatment, from patients with white coat hypertension (WCH), who would be only followed up. The diagnosis, treatment and control costs were obtained from 446 mild hypertensive patients from the Primary Health Care Center Aranbizkarra II (Vitoria, Spain) during 1996. For each gender, the overall costs per patient were estimated in both conventional and ABPM methods in terms of mean diagnosis age and WCH percentage. RESULTS: For 45 years old patients and 30% of WCH, the overall costs per patient among men were 414,999 and 371, 101 pesetas with conventional and ABPM methods, respectively. From 30 to 60 years old patients, the ABPM method turned up to be less expensive as long as the WCH percentage was higher than 6%. Similar results were obtained among women with mild hypertension. CONCLUSIONS: ABPM can be accepted as an useful clinical tool for the screening of patients with conventional diagnosis of mild hypertension. On the one hand, ABPM allows to select patients with low cardiovascular risk (WCH). On the other hand, the savings resulting from treatment reduction and fewer physician visits are higher than the additional costs of ABPM recordings.

Ambulatory blood pressure monitoring and diagnostic errors in hypertension: a Bayesian approach.

Random variability of blood pressure complicates the diagnosis and subsequent treatment of hypertension. To evaluate the importance of the number of blood pressure measurements in the correct diagnosis and control of hypertension, the authors used a Bayesian model to estimate the true average blood pressure of a group of newly diagnosed hypertensives, then calculated the diagnostic error that would result from monitoring methods using 24 daytime measurements or from using only three random monitoring measurements. The study population consisted of 129 individuals with newly diagnosed mild hypertension according to standard criteria, who were also evaluated with an ambulatory blood pressure monitor. In true normotensives (daytime diastolic blood pressure <90 mm Hg), the negative predictive value with three measurements was 0.92, and it rose to 0.96 with monitoring methods. In mild hypertensives (90-104 mm Hg), the positive predictive value was 0.64 with three measurements and 0.84 with monitoring methods, thus reducing the rate of false mild hypertensives from 35% to 15%. Finally, in patients with moderate or severe hypertension (>104 mm Hg), the positive predictive value improved from 0.26 with three readings to 0.61 with monitoring methods. Similar results were observed with daytime systolic pressure measurements. As the number of measurements increased, the diagnostic error due to the random variability of blood pressure became progressively smaller. In cases of hypertension, the large improvement in predictive values may justify using monitoring methods to confirm standard diagnosis.