Commented by Claudio López Bruzual, MD
This follow-up study of respiratory infections based upon an application throws up revealing preliminary data on COVID-19 patients suffering from long-term symptoms.
Doctors have observed that COVID-19 patients have long-term symptoms of autonomic dysfunction and heart insult up to 6 months from the onset of the disease.
To analyze this phenomenon various studies have begun to be carried out. One of them was the so-called DETECT (Digital Engagement and Tracking for Early Control and Treatment) which consisted of a remote longitudinal, app-based research. According to its authors, this is the first study to examine data from long lasting wearable devices, for instance, long term ECG recording devices. This is a technology that consists of the use of a set of electronic devices that are incorporated into the user's body to interact with it continuously, and provide readings called wearable data.
To conduct this study, from March 25th, 2020 through January 24th, 2021, 37,146 adult participants from across the United States enrolled. They provided wearable data to better understand the individual changes associated with viral diseases, including COVID-19.
The following paper focuses on 875 individuals who reported symptoms of an acute respiratory disease. Those people were swab tested for COVID-19 and tested positive (n=234) or negative (n=641).
Cardiac and sleep pattern affectations of prolonged COVID-19
The sample that was subjected to this analysis consisted of two types of participants:
- 234 COVID-19 positive individuals with a mean range age of 45.3 years (18-76 years); of these, 164 were women (70.9%).
- 641 COVID-19 negative symptomatic individuals, with a mean range age of 44.7 years (19-75 years); of them, 455 were women (71.1%.
Individuals with COVID-19 took longer to return to their Resting Heart Rate (RHR), previous sleep pattern and baseline physical activity level, compared to symptomatic COVID-19 negative individuals.
The difference between the groups was more marked for Resting Heart Rate (RHR), as COVID-19 positive individuals initially experienced transient bradycardia, followed by prolonged relative tachycardia that did not return to baseline, on average, until 79 days after the onset of symptoms. The step count and amount of sleep returned to baseline before RHR at 32 and 24 days, respectively.
Individuals with COVID-19 experienced different trajectories in returning to their baseline RHR, compared to COVID-19 negative individuals. A small subgroup of 32 participants (13.7%) with COVID-19 maintained a RHR of more than 5 beats per minute than their baseline RHR, which did not return to their normal for more than 133 days.
During the acute phase of COVID-19 individuals in this group reported the following:
- A higher cough frequency: 27 participants (84.4%) versus 57 participants (55.3%) in the <1 beat per minute group, and 57 participants (57.6%) in the 1-5 beats per minute group.
- Body ache: 20 individuals (62.5%) versus 42 (40.8%) in the <1 beat per minute group, and 35 participants (35.4%) in the 1-5 beat per minute group.
- Shortness of breath: 9 participants (28.1%) versus 9 participants (8.7%) in the <1 beat per minute group, and 6 individuals (6.1%) in the 1-5 beat-per minute group, compared to the other groups.
Other relevant data
- The researchers found an impact of COVID-19 infection that lasted approximately 2 to 3 months, on average, but with substantial variability between individuals. This could reflect various levels of autonomic nervous system disfunction or potential ongoing inflammation.
- A different previous follow-up case study showed transient bradycardia lasting approximately 9 to 15 days from the onset of symptoms, which also was seen in this study.
- Data from the study suggest that early symptoms and increased initial response of Resting Heart Rate to COVID-19 infection may be associated with the physiological duration of recovery from this virus.
As you may have noticed, this study points to a novel path in terms of clinical research, since it combines data obtained from the use of wearable devices (such as long term ECG recording devices) with clinical variables collected by the use of applications. This allows monitoring large population groups.
