Measuring an individual's heart rate appears to produce closely related results when the measurements are taken by an electrocardiogram or captured by photoplethysmography using a device such as a smartphone, according to a study published in npj Digital Medicine.
University of California San Francisco researchers recorded 10-second heart rate measurements from 50 participants after five minutes of rest. Heart rate was measured by PPG using a smartphone-based app as well as ECG. The researchers calculated the average differences between the two methods in milliseconds and beats per minute.
Using data from the 50 study participants, the research team performed a cross-sectional analysis of health information collected from 66,788 Health eHeart Study participants collected between April 2014-18. UCSF and the American Heart Association conducted the Health eHeart Study, and participants in the study completed online surveys on topics including demographics, physical activity levels, medications and medical conditions.
To determine heart rate measured by PPG, the researchers included data from all Health eHeart Study participants who recorded at lease one heart rate PPG measurement through a mobile app. Results of the study showed that heart rate measured by PPG and ECG were highly correlated at 0.90. Additionally, the study produced the following heart rate "norms" through analysis of the collective dataset:
· An average, real-world heart rate of 79.1 BPM.
· Factors associated with an elevated heart rate included the number of medical conditions a person has, female gender, increasing body mass index and Hispanic descent.
· Increasing age was associated with a reduced heart rate.
The study authors concluded that because PPG was measured using a specific mobile app, the accuracy of the participants' measurements might vary based on individuals' different user interfaces. However, heart rate taken by PPG can provide insights on a wider variety of patient phenotypes and medical conditions, the authors added.