Abstract P012: Agreement In Same Day Research-Quality And Casual Systolic Blood Pressure Measurements: Insights From BETTER-BP

Introduction: Prior studies suggest that BPs measured casually during routine clinic workflow are higher than research-grade measurements. However, BPs in these studies were typically collected on different days. We sought to compare the influence of day of assessment on this difference, within the context of an ongoing randomized trial. Methods: This is a cross-sectional interim analysis of the BETTER-BP trial, which examines the effect of behavioral economic incentives for medication adherence on BP. Our study focused on concordance between baseline BP measurements and did not analyze trial outcome data. We included the first 171 participants (1/1/20-3/31/22). Research BP was measured in a seated position after a 5 minute rest period using a standard cuff (Omron HEM 907-XL). Casual BP measurements (most recent recording prior to the research measurement) as well as baseline characteristics were abstracted from the EHR. Participants were divided into two groups based on whether their casual BP was measured on the same day (vs different day) as their research BP. The mean systolic BP (SBP) obtained for research versus casual measurements were compared, for the two separate groups, using paired T-tests. Results: Mean age was 55 years, 49.1% were female, 93.2% were nonwhite, and 48.5% were Spanish-speaking. Common comorbidities were diabetes (48.5%) and obesity (49.1%). Among the 132 patients with same day measurements, mean research SBP was 139.2 ± 20.4 mmHg and casual SBP was 137.9 ± 16.4 mmHg (mean within person difference=1.3 mmHg; P=0.259). Among the 39 patients with different days of measurement (median 14 [IQR 6-47] days), mean research SBP was 136.5 ± 23.3 mmHg and casual SBP was 144.2 ± 18.9 mmHg (mean within person difference= -7.7 mmHg; P=0.007). Casual SBP was higher among patients with measurements on different days compared to patients with same day measurements (P=0.043). Conclusion: SBP measured casually during clinical practice were concordant with research-quality measurements when obtained on the same day. SBP measurements differed significantly when obtained on different days. These findings suggest that prior reports showing casual BPs to be consistently higher than research BPs may have been influenced by temporal variability.