Three Hours Ambulatory Blood Pressure: A Surrogate for Daytime Ambulatory Blood Pressure Assessment in the Pakistani Population

Accuracy of Short-Term Ambulatory Blood Pressure Measurements for the Diagnosis of Hypertension

Purpose The accuracy of the diagnosis of hypertension increases by obtaining repeated blood pressure values. This can be achieved by obtaining multiple office blood pressure measurements (OBPM) or by home blood pressure measurements (HBPM) or using ambulatory blood pressure measurement (ABPM). A 24-hour ABPM is recommended as the preferred modality to diagnose hypertension by the latest guidelines. In this study, we evaluated the diagnostic accuracy achieved by four short-duration-ABPM (sABPM) protocols, i.e., two-hour, four-hour, six-hour, eight-hour compared to standard 24-hour ABPM. Materials and methods We performed a prospective diagnostic accuracy study in individuals attending the medicine outpatient department. Participants were >18 years, had systolic BP between 130 and 150 mmHg, and were not previously diagnosed as hypertensive. Initially, two OBPM values were taken, and then the ABPM apparatus was applied for 24 hours, which recorded BP at every 30 minutes while awake and at every 60 minutes while asleep. We used four sABPM values (2-hour, 4-hour, 6-hour, and 8-hour sABPM) and OBPM values as index tests, with awake ABPM cut-off of greater than or equal to 135/85 as the definition of hypertension. Analyses were conducted using the R Statistical language (version 4.0.3; R Core Team, 2020) on macOS Catalina 10.15.6. Result Based on the 24-hour ABPM based reference standard definition, 76 (48.7%) individuals out of 156 were classified as hypertensive. The positive predictive value (PPV) of sABPM at two-hour, four-hour, six-hour, and eight-hour above the cut-off of 135/85 was 80.0%, 83.8%, 93.4%, and 94.8%, respectively. PPV increased from 83.8% to 93.4%, and the positive likelihood ratio (LR+) increased from 5.4 to 15.0 with an increase in the sABPM duration from four to six hours. Conclusion We conclude that short-duration ABPM for six hours has a good diagnostic accuracy amongst hospital attendees. It can act as an intermediary approach between multiple OBPM and standard 24-hour ABPM in this population.