LAUSR

Objectives: To explore the differences between the intra-individual variations of the first two, the last two, and all three repeated blood pressure measurements (BPM). Methods: We recruited 55,837 volunteers who took BPMs at community pharmacies. Of those, 49,820 had their blood pressures measured for three repeated times. Medical history and frequency of blood pressure self-monitoring were elicited using a structured questionnaire. Variations of BPMs were calculated using the coefficients of variation (CoV). Individuals were classified as infrequent blood-pressure self-monitoring (BPSM) if they took BPMs for three times or less per week. Results: Of the 49,820 individuals (mean age, 56.9 ± 16.0 years), 51% were women, 53% had hypertension, and 85% were infrequent BPSM. As for systolic blood pressure (SBP), the coefficient of variations of the first two, the last two, and all three repeated BPMs were 2.9 ± 3.1%, 2.5 ± 2.7%, and 3.2 ± 2.8%. As for diastolic blood pressure (DBP), the coefficient of variations of the first two, the last two, and all three repeated BPMs were 3.3 ± 3.7%, 2.9 ± 3.4%, and 3.7 ± 3.4%. As both for SBP and DBP, the CoV of all three repeated BPMs were largest (p < 0.01), and those of the last two BPMs were smallest (p < 0.01). As showed in the Figure, the multivariate logistic analysis revealed that, as compared with the variations of the last two diastolic BPMs, current smoker (odds ratio, 1.13; 95% confidence interval, 1.02 – 1.07) predisposed individuals to have the greater variations of the first two diastolic BPMs; while, as for SBP, the associations with clinical characteristics was not found. Conclusion: Our findings demonstrated that the last two of the three repeated BPMs have smallest intra-individual variations, whose associations with cardiovascular events warrants further cohort studies.