SYSTEMATIC DIFFERENCE BETWEEN BLOOD-PRESSURE READINGS CAUSED BY CUFF TYPE

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 greater than or equal to 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 greater than or equal to 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.