Mean Blood Pressure of the General Population with the Mean of Three Measurements Versus the Mean of the Second and Third Measurements. Ricarto Study

Abstract

Introduction: Our aim was to determine the difference between measuring blood pressure (BP) with the mean of three determinations versus the mean of the second and the third determinations in a random general population sample. Methods: Epidemiological study of the general population aged ≥ 18 from the Health Area of Toledo (Spain), based on the health card database. Three readings of systolic and diastolic BP were taken with validated oscillometric devices OMRON HEM-907. The mean of the three readings was compared with the mean of the second and third readings after discarding the first measurement. We analyzed age, sex, BMI, abdominal obesity, dyslipidemia, diabetes mellitus, smoking and sedentary lifestyle. A descriptive study was conducted, as well as the agreement in the diagnosis of hypertension. Results: 1532 subjects were analyzed (mean age 49.01 ± 15.79 years old, 55.5% women). Response rate 36.3%. The mean systolic BP with three readings was 125.39 ± 17.43 mmHg, versus 124.33 ± 17.07 mmHg with the mean of the second and third readings (mean difference 1.01 ± 4.31; Cohen’s D = 0.059). The mean diastolic BP was 73.93 ± 10.89 versus 73.71 ± 10.93 mmHg with both methods (mean difference 0.19 ± 2.11; Cohen’s D = 0.017). Differences by age, sex, BMI, abdominal obesity, dyslipidemia, diabetes, smoking and sedentary lifestyle were all small (Cohen’s D < 0.08). The agreement between both models for classifying subjects as hypertensive/non-hypertensive showed a Kappa value = 0.936 (McNemar’s test p < 0.001). Conclusions: Determining the mean of three readings of BP does not make a significant difference in relation to the reading of the second and third measurements in a sample of general population.