Comparison of the Average of Five Readings with Averages from Fewer Readings for Automated Oscillometric Blood Pressure Measurement in an Outpatient Clinic

ABSTRACT

BACKGROUND AND OBJECTIVES: The optimal number of consecutive measurements for obtaining an average blood pressure (BP) reading in clinical practice is yet undefined by research. This study aimed to compare readings obtained from an average of 5 with averages of 2, 3, and 4, sequential measurements. SUBJECTS AND METHODS: Using an automated oscillometric device (BpTRU), BP measurement was conducted on 410 consenting adults attending a general outpatients clinic. Comparison of an average of 5 readings with averages of 2, 3, and 4 readings involved evaluation of correlations, Bland-Altman analysis, comparison of means and distribution of readings, and determination of the proportion of differences between compared readings which were clinically non-significant. RESULTS: 397 (96.8%) sets of complete BP readings were suitable for analysis. Clinically non-significant differences ( or =140 mm Hg and or =90 mm Hg for systolic and diastolic readings, respectively. Strong positive correlations were found between 5 average readings and each of 2, 3, and 4 average readings, respectively. CONCLUSION: An average of 5 readings may be excessive for routine BP measurement using this device at outpatient clinics.