Pressão Arterial:Implicação do número de medições na estimativa da prevalência da hipertensão

Abstract

The diagnosis of arterial hypertension should be based on multiple blood pressure (BP) measurements, taken on at least two separate occasions. We aimed to assess the impact of considering different criteria for arterial hypertension definition, based on the numbers of visits for BP measurements, on the estimate of arterial hypertension prevalence and to compare these estimates with two variables definitely related with arterial hypertension, body mass index and left ventricular hypertrophy. We used data from a cross-sectional study of 739 participants, aged 45 years, randomly selected from a non-institutionalised Portuguese population, from January 2001 to December 2003. Main outcome measures were prevalence of arterial hypertension (systolic BP 140 mmHg and/or diastolic BP 90 mmHg or current antihypertensive drug therapy) based in BP measurements in one evaluation, based in BP measurements in a second evaluation or based on fulfilling the same criteria in the two different evaluations, separated by a median of 14 days. We assessed the association between hypertension according to these three criteria with the body mass index and left ventricular hypertrophy. Estimated arterial hypertension prevalence was 63.4% (95%CI:59.8-66.9) using BP measurements from the first evaluation (HTN1) and it was 60.2% (95%CI:56.6-63.8) using BP measurements from the second evaluation (HTN2). If we use both evaluations criteria the estimate arterial hypertension prevalence (HTNFinal) was 56.3% (95%CI: 52.7-60.0), p(McNemar)<0.001, between HTN1 and HTNFinal and between HTN2 and HTNFinal. All the tree different estimates of arterial hypertension prevalence have a similar strong and independent association with body mass index (Odds Ratio=2,71 for body mass index 30 Kg/m2 with HTNFinal) and with left ventricular hypertrophy (Odds ratio=3,21 for HTNFinal with left ventricular hypertrophy). In many individuals labelled as hypertensive on a single evaluation, hypertension was not confirmed on reassessment, leading to a significant overestimation of 14.6% of the true value of prevalence. That is why the measurement of BP should be made at least in two office evaluations both for clinical purposes and in epidemiologic studies. On the other hand, an abnormal high BP measurement, in an individual older than 45 years old, is associated with HVE.