OXAM prospective cohort study: Ambulatory blood pressure monitoring in primary care
Ed Juszczak and Doug Altman with Martin Dawes (Oxford, now Montreal) and the Oxford Ambulatory Blood Pressure Monitoring (OXAM) Study Committee
The relationship between clinic readings of blood pressure and the risk of cardiovascular morbidity and mortality is well established. However, the recommended method of estimating blood pressure in a clinical setting is subject to error due to problems of observer bias, terminal digit preference, inaccurate equipment, threshold avoidance and the rapid loss of the effects of technique training.
Ambulatory blood pressure monitoring (ABPM) has the potential to overcome most of these problems. In addition, by taking into account the variability of blood pressure, ABPM may be a better predictor of cardiovascular risk than conventional measures. However, there is very little evidence on the use of ABPM in primary care. In 1992 Oxfordshire Health Authority gave ambulatory blood pressure monitors to 52 general practices; thus an ideal opportunity arose for assessing their everyday use in practice in a community setting. The OXAM project is investigating issues such as the practical problems of routine ABPM in primary care; the prevalence and determinants of ‘white-coat’ hypertension; and prognosis (mortality) in relation to level of ambulatory blood pressure and white-coat hypertension.