Time points for obtaining representative values of 24-hour blood pressure in chronic kidney disease

Background/Aims: Ambulatory blood pressure (BP) monitoring has been widely recommended for evaluating the status of BP, but is lacking in practicality. Determination of the specific time points for BP measurement that are representative of 24-hour mean BP could be useful and convenient in hypertensive patients with chronic kidney disease (CKD). Methods: A total of 1,317 patients for whom 24-hour ambulatory BP monitoring was performed were enrolled in a multicenter study on hypertensive CKD. We analyzed the time points at which systolic blood pressure (SBP) values exhibited the smallest differences from 24-hour mean SBP (mSBP). We included office mSBP and analyzed the relationships between SBPs at the office and the time points with the smallest differences from 24-hour mSBP using several methods. Results: The time points with the smallest differences from 24-hour mSBP were 7:00 AM, 2:00 PM, and 9:30 PM. In regression analysis, SBPs at 7:00 AM and 9:30 PM were better correlated with 24-hour mSBP than SBPs at 2:00 PM and the office. The proportions of patients with SBPs within 30% of 24-hour mSBP were higher at 7:00 AM and 9:30 PM. The best consistency between the uncontrolled hypertensive groups, defined as ${\geq}135mmHg$ of 24-hour mSBP and higher values of SBPs corresponding to 135 mmHg of 24-hour mSBP, were observed at the 7:00 AM and 9:30 PM time points. Conclusions: The specific time points for SBPs that correlated well with 24-hour mSBP in hypertensive CKD patients were 7:00 AM and 9:30 PM.