Characterizing Agreement in the Level of Interarm Blood Pressure Readings of Adults in the Emergency Department (CALIBRATE Study)

Background: Increased interarm systolic blood pressure difference (IASBPD) is one of the major predictors of cardiovascular disease. An IASBPD of >10 mmHg is of clinical significance. However, studies have reported a high number of patients visiting the emergency department (ED) with high IASBPD and varying correlation of IASBPD to age, ethnic background, and comorbidities such as hypertension and diabetes. Objective: The CALIBRATE study aimed to measure the IABPDs in the multiethnic patient population presenting to the ED in Qatar and to assess the distribution of IASBPD in this population. Methods: In a sitting position, two consecutive blood pressure (BP) measurements were recorded from the right and left arms for each participant using a calibrated automated machine and appropriate cuff sizes. The data were recorded using predefined data fields, including patient demographics, past medical, and social and family history. The continuous variables were reported as mean or median based on the distribution of data. The data were analyzed using Stata MP 14.0. Results: A total of 1800 patients, with a mean age of 34 (10) years, were prospectively recruited from the ED. The median absolute systolic BP difference (ΔSBP) between the right and left arms was 6 (3–10) mmHg, and it was the same for the first (ΔSBP1) and the second readings (ΔSBP2). The absolute average of ΔSBP1 and ΔSBP2 was 7 (4–10) mmHg. The difference in systolic BP difference (SBP) of < 20 mmHg for interarm blood pressure was seen in the 95th percentile of the population. No meaningful association could be detected between the IABPD and the study variables such as age, demographics, regions of interest, and risk factors. Conclusion: In population presenting to the ED, the IASBPD of at least 20 mmHg reached at the 95th percentile, validating the known significant difference. The utility of SBP difference can be improved further by taking the average of two individual readings.