Variability of blood pressure and the results of screening in the Hypertension Detection and Follow-up Program

Abstract

The variability of blood pressure readings of individual subjects is known. This intraindividual and inter-individual variation has important implications for blood pressure screening programs, as well as for clinical and epidemiological studies. The Hypertension Detection and Follow-up Program (HDFP) included a two-stage screening of approximately 159,000 men and women, 30–69 yr of age in 14 United States communities. Three readings were taken at home with a standard mercury sphygmomanometer. Persons found positive were re-screened in special clinics within 2 weeks, where two readings using standard sphygmomanometers and two readings using a Random Zero device were obtained in alternating order. Analyses demonstrated that: (1) between individual variation increased with age and differed by previous history of hypertension and treatment status; (2) within individual variation was related to age, race, sex, history of hypertension and treatment status as well; (3) use of the Random Zero device appeared to reduce the influence of previous readings as demonstrated by increases in the average within individual variation.