Systematic difference between blood pressure readings caused by cuff type

Abstract

In this study we determined whether blood pressure readings using a cuff of fixed size systematically differed from readings made with a triple- bladder cuff (Tricuff) that automatically adjusts bladder width to arm circumference and assessed subsequent clinical and epidemiological effects. Blood pressure was measured with a standard cuff or a Tricuff in 454 patients visiting an outpatient clinic in the Seychelles (Indian Ocean). Overall means of within-individual standard cuff-Tricuff differences in systolic and diastolic blood pressures were examined in relation to arm circumference and sex. The standard cuff-Tricuff difference in systolic and diastolic blood pressures increased monotonically with circumference (from 4.7±0.8/3.2±0.7 mm Hg for arm circumference of 30 to 31 cm to 10.0±1.1/8.0±0.9 mm Hg for arm circumference ≥36 cm) and was larger in women than men. Multivariate linear regression indicated independent effects of arm circumference and sex. Forty percent of subjects with a diastolic blood pressure of ≥95 mm Hg measured with a standard cuff had values less than 95 mm Hg measured with a Tricuff. Extrapolation to the entire population of the Seychelles decreased the prevalence of blood pressure greater than or equal to 160/95 mm Hg by 11.5% and 24.0% in men and women, respectively, aged 35 to 64 years. The age- adjusted effect of body mass index on systolic and diastolic blood pressures decreased twofold using blood pressure readings made with a Tricuff instead of a standard cuff. Because of a systematic difference, blood pressure readings made with a cuff of fixed 12-cm width instead of with a Tricuff substantially overestimate the prevalence of high blood pressure and the effect of body mass index on blood pressure.