Prevalence of isolated systolic hypertension in the population over 55 years old. Results from a national study.

We concluded that ISH prevalence ranges between 20.3% in primary" care patients and 35% in the community, using mean values of both systolic and diastolic BP. ISH prevalence is higher among women; it increases with age, decreasing slightly after the age of 70. Risk factors include gender, age and family history of hypertension. The predictive value for ISH diagnosis is 100% and 65% with methods ISH-1 and ISH-2 respectively, with positive predictive value of 51.05% and 63% for ISH-1 and ISH-2 respectively. Orthostatic hypotension prevalence is higher at 5 minutes than at 2 minutes and is higher among elderly subjects. The prevalence of untreated hypertension in the Portuguese population aged over 55 years, according to the WHO/ISH criteria, was 44.92%.