Influence of correction for within-person variability in blood pressure on the prevalence, awareness, treatment, and control of hypertension.

We assessed the influence of correction for within-person variability (WPV) on the prevalence, awareness, treatment, and control of hypertension. Data were collected from two cross-sectional population-based studies on cardiovascular disease risk factors from 1987 to 1995 among 56,026 subjects aged 20 to 59 years. Correction factors were calculated from an internal reproducibility study among 924 subjects who were examined in 1989 and 1990. The prevalence of hypertension without a correction of blood pressure values for WPV was substantially overestimated (38%), whereas the prevalence of awareness and treatment of hypertension were substantially underestimated (-13% and -28%). The prevalence of control of hypertension did not change much after this correction. It may be advisable to perform a correction for within-person variability to obtain valid prevalence estimates in surveys that only take one or two measurements of blood pressure.