Ambulatory blood pressure in the hypertensive population: patterns and prevalence of hypertensive subforms.

BACKGROUND: A number of clinically identifiable patterns of blood pressure elevation are apparent using ambulatory measurement Their prevalence and age and sex distribution have not been described. The purpose of this study was to describe the epidemiology of patterns of high blood pressure in a large population.

DESIGN: Retrospective database analysis of referral hypertensive population.

PATIENTS: Clinic and ambulatory blood pressure measurements were performed in 2092 patients with essential hypertension while they were not taking antihypertensive medication.

METHODS: The patients were classified into six groups on the basis of their ambulatory blood pressure monitoring profiles: white-coat hypertensives, borderline hypertensives, isolated systolic hypertensives, isolated diastolic hypertensives, combined systolic and diastolic hypertensives and nocturnal hypertensives. The categories were examined for age and sex differences.

RESULTS: All patients were categorized into one of the six groups. The majority (56.2%) were systolodiastolic hypertensives, 12.9% were borderline and 10.8% were white-coat hypertensives. Isolated systolic hypertensives comprised 6.2% of the population, isolated diastolic hypertensives 6.9% and nocturnal hypertensives 7.1%. The isolated systolic hypertensives showed the greatest change with age, with a prevalence of < 5% in patients below 40 years of age, rising to almost 20% in the 70 plus age group. White-coat, isolated diastolic and borderline hypertensives showed the opposite change in prevalence, falling from younger to older age groups. Apart from a greater prevalence of white-coat hypertension in females, the patterns were largely similar between sexes.

CONCLUSIONS: Ambulatory blood pressure monitoring allows the blood pressure pattern to be defined in hypertensive patients. The patterns identified here in a referral hypertensive cohort show changes in prevalence with age, and further study is required to determine the prognostic significance of hypertensive sub-forms.