Context:
Since the outbreak of SARS-CoV-2, health care systems have been subject to increased pressures. This is mainly due to infected patients being admitted to the medical wards and intensive care units, but also due to the requirement to reduce exposure of both healthcare professionals and patients to COVID by minimising contact. There are indications that reduced access to healthcare services during the pandemic is responsible for more than half of excess deaths in the United States. In response to this, the CDC is advocating the use of telemedicine to keep providing a remote version of healthcare services. A study of telemedicine services in China used during COVID-19 pandemic showed that they reduced burden on hospitals, prevented overcrowding, reduced the risk of cross-infection, and relieved patients' anxiety. The use of telemedicine is also being developed in Europe, where many patients are being denied the use of clinical services, like cardiac rehabilitation, because of centres being closed. In the context of the NHS, an increased use of telemedicine services is being observed. The NHS long-term plans do, in fact, include tele-consultations as a pillar for its sustainability. Healthwatch have produced useful advice for outpatient clinicians to consider avoiding asking patients to attend physical outpatient appointments where a clinically-appropriate and accessible alternative exists. Where an appointment is clinically necessary, the national benchmark is that at least 25% could be conducted by telephone or video including 60% of all follow-up appointments. Initial promising results are being seen in the context of diabetes, where virtual clinics are recommended as mitigation to the pandemic.
The 6MWT:
To assess patient's exercise capacity, the six-minute walk test (6MWT) is a standard method used in patients with cardiopulmonary disease such as Heart Failure (HF) or Pulmonary arterial Hypertension (PAH). The 6MWT measures how far a patient can walk in 6 minutes. Walking is an activity performed every day, by most patients except for those most severely limited. By assessing patients' ability to exercise, the 6MWT provides a global assessment of respiratory, cardiovascular, neuromuscular and cognitive function. The 6MWT does not differentiate what limits the patient, nor does it assess maximal exercise capacity. Instead, the 6MWT allows the patient to exercise at a daily functional level, and is a useful tool for assessing changes after a therapeutic intervention, and correlates with a subjective improvement in dyspnoea.
In PAH the 6MWT is used to evaluate patients' response to treatment, with an increase in 6MWT distance of greater than 42 m being considered a clinically significant improvement . Furthermore, change in 6MWT distance correlates with VO2 max, NYHA class and mortality in those patients, providing an objective assessment of disease progression, prognosis and response to treatment. It is a universally accepted test as it is safe and easily performed by the patient.
Cardiovascular outpatient management during the pandemic:
Since the outbreak of SARS-CoV-2, the standard regime of care for outpatients with cardiovascular disease has been affected. For example, in PAH patients, the normal regime of a 6MWT, echocardiogram and face to face consultation was abandoned as those patients were felt to be extremely clinically vulnerable, and therefore were recommended to shield at home. Therefore patients needed to be assessed without having any face to face contact, unless in an emergency. In cardiovascular outpatient clinics in Oxford, patients were regularly contacted by phone to replace face to face visits. During these phone calls, questions about the general status of the patient are asked, i.e. how far they think they can walk and whether they have noticed a change in their exercise capacity or functional capacity, but no objective data, like the results of the 6MWT, were available for assessment.
Telemedicine services for pulmonary hypertension:
In a previous research project called 6APP, we designed, developed and evaluated a mobile-health "app" (a type of telemedicine where patients use their mobile phones), to allow them to perform the 6MWT in the community. We hypothesized that a test conducted by patients, in their environment, would reflect more the patient's functional status, would free up healthcare resources and would be less stressful and costly for the patients themselves.
The app allowed patients to perform the test both indoors, by walking back and forth along a corridor of fixed length, and outdoors, using the localization system (like the GPS). In our study with 30 PAH patients, we proved that the app is accurate when used outdoors, the measurements are reliable and repeatable and the method is well-accepted by patients. After these encouraging results, the app has been simplified and made available for free for both Android and iPhones under the name of "Timed Walk". The original app was developed by Dario Salvi at the Institute of Biomedical Engineering of the Oxford University. The current app, which uses the same validated outdoors test approach, is instead maintained by the Malmo, University Sweden, where Dr. Salvi is currently employed.
Given the circumstances during the pandemic period, the PH clinic in Oxford and other cardiovascular outpatient clinics were recommending patients to use the Timed Walk app, the results of which were being used by the clinical team to assess patients in addition to their symptoms and general well-being. This is felt to be more appealing to the patients, and would reduce the time spent in hospital on the day of their outpatient appointment. The app only allows outdoor tests (as these proved to be more reliable and practical) and to share 6MWT data via email if patients want to.
Goal:
The goal of this study is to contribute to existing research on the adoption of remote mobile-based 6MWT through a mixed methods approach where we mix of complementing quantitative and qualitative data to validate the use of an app within the context of the pandemic.
Methods:
Outpatients undergoing follow up in the cardiovascular outpatient clinics in Oxford, who were able to walk and use a smartphone, were considered eligible. Some of these patients were already using the app, prior to the start of the study, for example in the case of the pulmonary hypertension clinic. Prospective participants were approached by a member of the clinical team for consideration and recruited during their regular outpatient consultation either via phone call or during a visit to the clinic. Participants in the study were asked to download the Timed Walk app and use it to perform a 6MWT in the community, outdoors, at least once a month, and to report the measured 6MWD to the clinicians during the outpatient consultations, via phone or in the clinic.
We did not sample participants as the aim was to involve all patients in the cardiovascular clinics who required a 6MWT and were able to use the app. However, as restrictions started to be lifted in 2022 and practical reasons made the recruitment pace slower than desired (about 4 patients per month), a decision was made to stop recruitment after the 100th patient was selected.
In order to assess the impact the app had on the clinical management of consented patients, at each consultation (either through phone or face to face visit) the clinician who contacted the patient logged any study-related event on a spreadsheet marked with a code, including distance walked during the 6MWT and medical decisions taken. Coding was used to simplify and automate later analysis and was defined in collaboration with the clinical professionals that were part of the study.
As one of the aims of the study was to understand if patients are able and willing to use the app, we used and adapted the broad and validated technology acceptance model for mobile health services and the uMARS questionnaires.
In addition to clinical impact and user acceptance, we wanted to confirm the reliability of the app-based measurements by comparing the 6MWD gathered through the smartphone with a reference. A group of 12 volunteers, patients and staff, were invited after the study period was completed. This included performing 10 6MWT each, using the app and a trundle wheel used as reference simultaneously.
To study the accuracy of the estimated distance under different conditions, participants were instructed to perform 5 tests walking along paths known to obtain the best distance estimation (straight or gently curved paths) and 5 tests walking over paths that are suspected to be more challenging for the app (including narrow curves, U-turns or in confined spaces). We refer to the former type of path as conventional and the latter as unconventional.
