Telesolutions have been increasingly developing during past epidemics, e.g., for contact investigations and disease control6. In the time of the Ebola outbreak between the years 2014 and 2016, a mobile application helped to trace and monitor confirmed cases14, increasing the time to case registration, completeness, and security of the data. When SARS-CoV 1 was dealt with in Taiwan, online communication via a webcam increased the availability of medical consultations and reduced their costs15. Swiss teleservice notifications associated with fever were proven to reflect influenza activity16.
Lately, the pandemic situation forced outpatient care out of the doctor’s office. Italian authors, like Omboni17, complained of insufficient telemedicine implementation during the first striking COVID-19 wave and suggested it is a must in a modern healthcare system, especially in terms of chronically-ill patients during a lockdown. Nevertheless, more attention in the literature has been put on telehealth concerning home-isolated COVID-19 patients and controlling their disease18, especially after the unpredictable character of SARS-CoV 2-associated pneumonia presented itself throughout the world. The China health center19 has set up a network for COVID-19 alert and response with 126 network hospitals involved. Between January 28 and February 17 in 2020 63 teleconsulted patients had severe pneumonia alongside 591 were moderate cases. At that time, there were mobile devices used for collecting, evaluating, and reporting patient vital signs to the caring team in isolation wards. The authors outline that the bedside system allowed to limit the exposure to patients’ contagious secretions and the communication system was utilized to build and remotely train multidisciplinary health teams for a more comprehensive treatment. An utterly different telesurveillance solution for home-treated patients based on questionnaires in a mobile application has been developed by a French group20, with more than 65,000 users in Paris, and it consisted of Medical Responders and physicians reacting to changing subjective health status of ill individuals.
The effects of telemedicine implementation and its impact are well known in cardiology, with trials such as the TIM-HF221 which demonstrated that remote telemonitoring reduced days lost due to unplanned cardiovascular hospitalizations, as well as documented a decrease in all-cause mortality among patients managed in the study. In chronic obstructive pulmonary disease, our research group has previously shown that a decrease in saturation exceeding 4% can predict an exacerbation in the forthcoming 7 days22. With enough time and training, home spirometry starts to correlate with hospital spirometry among the idiopathic pulmonary fibrosis group23. Among the less obvious effects of telemedicine-enhanced home care, the worth-to-consider effects are both improved psychological well-being and individually tailored treatment decisions.
Much is known about the average recovery after COVID-19 pneumonia and persistent symptoms; however, the variety of research does not answer the question of which patients should be supervised with special attention. To our knowledge, no other group monitored patients at home for a longer period than we managed to do. This study aimed to stratify the usefulness of day-to-day saturation and heart rate measurements, as well as the subjective extent of dyspnea and cough, in post-COVID care among previously hospitalized survivors. Our findings suggest that a patient who provides at-rest saturation measurements lower than 94% will not significantly improve in pulmonary function tests—FVC and DLCO—after 2 to 3 months post-discharge. This equals continuous exercise intolerance.
Most of the existing research associated with COVID-19 and telehealth considers the acute infection stage, sometimes with a short sequence afterward. Motta et al. monitored saturation, heart rate, body temperature and peak expiratory flow of 12 patients during 30 consecutive days of acute home-treated individuals with mild to asymptomatic SARS CoV 2 infestations to evaluate a quick response system during the worsening symptoms24. The findings have shown a significant decrease in SpO2 and an increase in heart rate during the illness, while PEF values dropped below 80% of the normal range among 4 of the participants. The authors outlined that there was not enough data to guide the use of home pulse oximetry or validate it in disease progression.
O’Carroll et collaborates used remote oxygen saturation monitoring in COVID-19 cases to facilitate the discharge of non-oxygen-dependent patients and have their safe follow-up25. During the median time of 12 days of measurements, the telemonitoring allowed to detect 3/18 patients with desaturations because of worsening COVID-19 infiltrates and 1/18 worsening from hospital-acquired pneumonia developing after the hospital discharge. Telemedicine served its role—it allowed managing patients’ conditions in a more controlled manner; no one from this group (4/18) required non-invasive or invasive ventilation during readmission. Of note, the alerts that lead to medical attention were programmed to be generated after every measurement lower than 94% SpO2, consistent with our findings. The frequency of measurements was higher (mean 3.9 vs 5.7 per day) in the readmission group25; our own observations showed a higher cooperation rate among more seriously ill (non-improvers). Similar research from Grutters et al. proved the 5-day (± 3.8) shortening of hospital stay among the 33 participants group via the use of telehealth. It also allowed a safe follow-up with 3 readmissions and 1 pulmonary embolism diagnosis, along with the cost-effectiveness of a whole system. Most patients in these studies rate telemonitoring to be friendly and useful.
Research by Martínez-García et al. included two groups of patients in the surveillance26: 224 outpatients traced from the beginning of the disease and 89 inpatients after discharge. Every patient provided oxygen saturation and temperature 3 times a day. Proactively, the patient was reached at least once a day. Until the termination of the study after 30 days, 38 (16.90%) outpatients were referred to the Emergency Department, 18 were hospitalized (8.03%), and 2 were deceased. One patient from the inpatient group was re-hospitalized and one left the study. Importantly, neither deaths nor vital emergencies happened at home. The average time of monitoring was 11.64 (± 3.58) days, and 224 (73.68%) patients were discharged during the 30 days of the study.
Patients are reluctant to participate in telehealth research for various reasons explored e.g. by Sanders et al.27. Most anxiety comes from technical requirements—which are often misunderstood and exaggerated. There is a group of patients that consider telemedical surveillance with a high degree of dependency and ill health, which is unbearable to them. At the same time, others are glad to have their current healthcare providers and they are hesitant about the care methods they are unfamiliar with. Great telemonitoring adherence data comes from the paper by Lang et al.28. Among the analyzed group, some participants withdrew from the study during its course—referred to as the drop-outs. 41 patients gave reasons for dropping out after a period of sending data. They can be further categorized into groups: no perceived benefits for health; no need for telemonitoring; investing too much time in participation; insufficient user-friendliness; feeling a loss of privacy. The most mentioned reasons for dropping out were no perceived benefit (19/41; 46.3%) and the lack of telemonitoring needs (18/41; 43.9%). Cook29 also outline that the majority of users resigning from telehealth did not find the equipment useful once they had tried it, while Foster’s30 telehealth engagement study reported that as much as 40.1% (n = 2852) of decliners did not feel a need for additional health support, 27.2% (n = 1932) stated being too busy to use it and 15.3% (n = 1092) of decliners were not interested in the research. This data is greatly consistent with our findings, where non-adherence and omitting the daily measurements are correlated with functional improvement after COVID-19. We did not investigate participants’ motivation though, so we can only speculate that they did not feel the necessity to stay under strict surveillance.
Compared to the research cited above, our prospective study is unique because we prolonged the monitoring until a minimum of 2 weeks of SpO2 ≥ 95% with a mean observation time of 67 (range 45–114) days. The program allowed us to notice serious events in patients’ individual post-COVID history. It becomes crucial when you realize a striking study by Chopra et al.3 who depicted that from 1250 COVID-19 survivors in the US State of Michigan 84 patients (6.7% of hospital survivors and 10.4% of ICU-treated hospital survivors) died in the following 60 days, bringing the overall mortality rate for the cohort to 29.2% hospitalized and 63.5% of treated in ICUs. Data from Bellan et al. further confirm these results with 5% post-discharge 30-day mortality31. Furthermore, 189 convalescents (15.1%) became re-hospitalized in the same period. In our group, one of the patients returned to a hospital during the study because of Clostridioides difficile diarrhea as a post-hospitalization and post-antibiotic consequence. At the time of observation, the additional diagnoses were: one outpatient post-COVID pulmonary embolism; one hereditary thrombophilia (in another person); two asthma diagnoses; urinary bladder ulcers of possible viral etiology in one patient; myocarditis (two suspected and one of them confirmed in the MRI). There was also one underlying interstitial lung disease suspected but the final diagnosis of severe emphysema with overlapping post-COVID radiological changes has been determined. None of the participants died or had rapidly worsening respiratory parameters. Worthy of note, those hospitalized in pulmonary rehabilitation units reported notable subjective improvement. The efficacy of post-COVID pulmonary rehabilitation is undoubtedly beneficial in research papers32. Such a statement cannot be assigned to pharmacological interventions so far.
On the other hand, the heart rate measurements did not prove to be useful in our real-life telemonitoring study, probably because compensatory tachycardia was deeply modified by the use of medications like β-blockers and ivabradine. We were also disappointed with dyspnea and cough self-assessment scales that did not correspond with pulmonary improvement. Interestingly, it appears from existing studies that there is no significant difference in PFTs when comparing patients with persistent COVID-19-related symptoms and asymptomatic ones33.
The study could not consider confounding factors. The main limitation of our research is group heterogeneity; as explained in the methods section almost every patient hospitalized for COVID-19 pneumonia was allowed to join it. The severity of interstitial pneumonia among participants was not equal and men were the predominant sex. The starting point slightly differed between patients hospitalized in our unit and those from other centers, forming a possible bias. 6-min walk tests were performed with different supervisors and it probably had an impact on patients’ engagement in the test itself. The unique benefits come from a longer observation time and addressing the pulmonary function tests to pulse oximetry results; as far as we are concerned no other researchers found such a correlation. Every patient had technical training with access to technical and medical consultation whenever problems occurred; just to eliminate loss of data or potentially hazardous events.