This study has shown that, when a single practice assesses the proportion of treated hypertensive patients achieving the recommended blood pressure targets, office and ambulatory measurements of blood pressure give markedly different results. Assessing blood pressure control based on a single measurement and/or a single visit is unlikely to be reliable, but calculating the average office blood pressure over the previous year results in significantly fewer patients achieving the GMS target.
The study sample represented 86% of the eligible patients. Office blood pressure measurements were made using calibrated mercury sphygmomanometers and ambulatory blood pressure measurements using validated, calibrated devices. Data on the pre-treatment blood pressure was not collected which may have added to the study.
Providing a high quality service for patients with hypertension is dependent on being able to correctly identify those patients with suboptimal blood pressure control in whom additional treatment is necessary, and similarly identifying patients who have adequate blood pressure control (up to 30% will show a white-coat effect) in whom the risks and costs of additional treatment can be avoided. There is recent evidence that suboptimal ambulatory blood pressure is a more powerful prognostic indicator in treated hypertensives,5
and we have previously shown that annual ambulatory blood pressure monitoring is cost effective in this population of patients.6
There needs to be more specific guidance and standardisation in the methodology used for assessing blood pressure control, particularly if these measurements are being used as quality indicators of clinical practice.