Isolated systolic hypertension in an elderly Danish population. Prevalence and daytime ambulatory blood pressure

Isolated systolic hypertension (ISH) is a major risk factor for cardiovascular complications. Nevertheless, data on the prevalence in a representative population do not seem to be available. The prevalence of ISH and the white coat effect was thus studied in a cross-sectional survey of 2806 inhabitants aged 70-80 years. In untreated subjects, the prevalence of ISH was 17.4% (95% CI 14.9-20.2) in women and 13.5% (95% CI 11.3-15.9) in men using clinic blood pressure at first visit. The prevalence increased significantly with age. The prevalence was reduced to 10.4% when using the average of all-visits clinic blood pressures. By a simulation model, it was demonstrated that his reduction mainly resulted from a regression towards the mean. Average all-visits clinic blood pressure was 172.6 +/- 10.4/81.1 +/- 6.0 mmHg. Less than one-third of those with all-visit ISH had sustained ISH. Identifying subjects with sustained ISH requires measurements in more than three visits.