A recently published study in the New England Journal of Medicine shows that 24-hour ambulatory blood pressure monitoring is a better predictor of cardiovascular and all-cause mortality than just monitoring blood pressure in the clinic.
While the results may not be surprising, they are important validation for the growing field of remote patient monitoring, which generally holds that monitoring patients more consistently with wearable devices yields more accurate and more useful data than the status quo of measuring patients only in the clinic.
A team of researchers from the University of Madrid in Spain analyzed 10 years of data from 63,910 adults who had signed up for a blood pressure registry. All of the patients had both a 24-hour ambulatory blood pressure measurement and a two-visit clinical blood pressure measurement in their records.
In addition to finding that higher systolic blood pressure from an ambulatory measurement was a better predictor of death than higher systolic blood pressure from a clinical measurement, researchers looked at the differences between the two values in individual patients in order to group them into four cohorts. The group with high blood pressure for both scores was said to have “sustained hypertension” and the group with normal blood pressure in both scores was said to have “normotension.”
The group with elevated clinic hypertension but normal 24-hour hypertension was dubbed the “white coat” hypertension group (the white coat effect is a known phenomenon where people’s blood pressure goes up when it’s being measured, often because they find doctor visits to be stressful situations). The group with normal clinical hypertension and elevated 24-hour hypertension was said to have “masked hypertension,” as their high blood pressure wouldn’t show up in normal screenings.
Researchers found that the group with masked hypertension had the highest all-cause mortality out of any of the four groups.
“In our study, unlike most previous studies, we observed consistently greater mortality associated with masked hypertension than with sustained hypertension, which might be due to the delayed detection of masked hypertension in patients, who consequently could have more organ damage and cardiovascular disease than patients with sustained hypertension,” researchers wrote.
In addition, “white coat” hypertension was not found to be benign; patients with white coat hypertension had a higher mortality rate than normotensive patients.
The study had some limitations, including an all-white cohort and the fact that patients were generally only monitored for 24 hours a single time, as opposed to many remote patient monitoring programs that monitor patients over a longer period. Researchers also note that the study may have inherited a selection bias since they were only able to study patients who had been recommended 24-hour monitoring for some reason.
But still, the size of the study and its real-world nature make it a worthwhile contribution to the ongoing conversation about the efficacy and importance of continuous patient monitoring.