Assessment, Monitoring and Optimisation of Prehabilitation Patients Using Wearable Fitness Trackers

Optimising patients pre-operatively or "Prehabilitation" is a relatively new and evolving concept in patient care. Prehabilitation utilises prescribed exercise in the time prior to surgery with the aim of improving a patient's functional capacity enabling them to better withstand the stress of surgery. 1-3 This is required due to the physiological insult cause by surgery, particularly in those with cancer, which in turn results in a decline in patients' function.

Post-operative restorative rehabilitation programmes such as Enhanced Recovery After Surgery (ERAS) are commonplace and used with the aim of returning the patients' function towards their preoperative baseline. ERAS has been shown to improve postoperative outcomes, including length of stay, re-admission, and complication rates.4 Prehabilitation has been shown to both improve cardiovascular fitness prior to surgery5,6 and like ERAS reduce post-operative complications.7,8 However, despite this and unlike ERAS, it's use is still patchy, with no national protocols in existence.

Due to evidence demonstrating its effectiveness, the benefits of commissioning prehabilitation services have been acknowledged in several surgical fields,9 with national policy documents from NHS England placing an emphasis on preventative rehabilitation, delivered before and during cancer treatment.10 As such, the policy environment could be seen as favourable. However, there is little evidence available, and significant heterogeneity in that which is available, for how best to approach a prehabilitation service to achieve the best results.

Physical activity is a core component seen across all reported prehabilitation programmes. However, heterogeneity is seen across multimodal programmes, meaning the type of exercise, duration and supervision of physical activity is inconsistently administered between studies. Additional interventions such as dietary support, psychological wellbeing and smoking cessation are also variably addressed in some studies.

Accurate, reliable, and reproducible assessment of cardiopulmonary fitness is required to effectively prescribe and monitor patients as they progress through a prehabilitation programme. Currently, cardiopulmonary fitness assessment requires patients to attend for in person assessment to undergo Maximal or Submaximal exercise testing.

WEARABLE ACTIVITY TRACKING AND EHEALTH TECHNOLOGIES IN HEALTHCARE

Wearable "fitness tracking" technologies incorporating sensors which monitor activity and physiological parameters are now pervasive and are a rapidly expanding commercial industry worldwide with a market size valuation of USD 37.10 billion in 2020, and a projected compound annual growth rate of 15.9% from 2020 to 2027.11 With significant investment in this technology leading to increasing functionality, reliability and aesthetics it opens up the potential for use in a healthcare setting where to date their use has already been shown to be both feasible and insightful in the perioperative setting.12 Intuitively, these devices could provide a beneficial aid in prehabilitation programmes. However, a literature review found no studies have yet reported the use of wearable technologies on patients when used within a prehabilitation programme.

eHealth technologies are defined as the cost-effective and secure use of information and communications technologies in support of health and health-related fields13. They are already widely used by patients with 72% of internet users saying they looked online for health information of one kind or another within the past year14 and 69% of adults regularly tracking a health indicator like weight, diet, exercise routine, or symptom15. Utilising eHealth technology within prehabilitation may help to improve patient participation, particularly in home-based programmes. The assessment of exercise intensity is one possible area in which it could be used to overcome the limitations of self-assessment. Making it easier for patients to assess intensity and monitor the frequency that they are achieving their target activity may improve exercise behaviour and consequently improve the response to prehabilitation.

RATIONALE FOR CURRENT STUDY

Using fitness trackers in prehabilitation opens up the potential for remote programmes whilst maintaining objective measurement of heart rate and step count. Remote prehabilitation programmes, as opposed to in person individual or group sessions within a hospital setting are attractive to patients, health professionals and policy makers alike. For patients, the distance from home and the physical and financial demands of travel can negatively impact accessibility of programmes and the time available to complete exercises. Particularly pertinent for those travelling long distances to tertiary centres for cancer treatment and more recently with the risks of COVID-19 to those clinically vulnerable. Therefore, reducing unnecessary hospital visits is desirable. Remote assessment makes scheduling easier for clinicians and the use of wearable fitness trackers provides a more detailed understanding of individual parameters over longer periods, rather than a snapshot. For policy makers, remote assessment means reduced clinic and or gym space required, therefore reducing costs and reduced footfall (a key target resulting from the covid-19 pandemic) within the hospital to facilitate other scheduling commitments. Whilst many perceived benefits exist, it is also necessary to acknowledge that the use of fitness trackers and remote assessment may not benefit all, an area which will be addressed in this work. Whilst many remote programmes do now exist, the use of fitness trackers to support these programmes has not been assessed.

Exercise intensity Many reported programmes use a measure called Rating of Perceived Exertion (RPE) to measure exercise intensity. RPE is a widely used and validated scale that has been shown to accurately correspond to intensity measured by maximum heart rate (HRmax) in many different populations.16-18 However, as a self-reported measure, it is inherently prone to measurement bias; a preliminary study found that over 60% of RPE measurements made by patients during prehabilitation were overestimates of the actual achieved intensity measured by achieved heart rate. It is therefore proposed that using fitness trackers individuals could exercise to prescribed heart rate zones to improve achievement of their exercise targets. A heart rate zone is a range of heart rates which corresponds to a desired training effect for an individual. They can be calculated as a percentage of the heart rate reserve (HRR) which is the maximum heartrate (HRmax) an individual can achieve minus their resting heartrate (RHR).

Existing prehabilitation programs prescribe the intensity of aerobic exercises to patients by asking them to exercise to a rating of perceived exertion (RPE). As a self-reported measure, there is an inherent propensity towards measurement bias, with studies reporting over 60% of RPE measurements made by patients during prehabilitation as overestimates of the actual intensity achieved when measured by their heart rate. Therefore, I hypothesise that prescribing to a heart rate zone and providing a heart rate tracker to monitor this will increase the levels of moderate intensity exercise achieved.

Self-reporting and Adherence

Direct links have been reported between the amount of physical activity completed each week and post operative outcomes (lower risk of post-operative pneumonia with increasing volumes of activity completed in the pre-operative period). 19 However, current programmes are reliant on self-reported adherence, making assessment of the true benefits challenging. A previous study of the PREPARE programme found an average adherence of 64% to the prescribed exercise.20 Adherence to home-based exercises is often lower than supervised programmes 21 and exercise participation during chemotherapy is particularly challenging.22 It is therefore important to explore ways to remotely support and encourage patients to follow their exercise programmes during prehabilitation. Fitness trackers provide a potential objective measurement of adherence to prescribed targets.

It is beneficial to provide home (vs. hospital) based exercise programmes. However, their effectiveness dependent on patients' adherence to the prescribed physical exercises (currently self-reported via an activity log), where activity is frequently over-reported. Heart rate trackers provide data on activity level and therefore can be used remotely to determine compliance.

Patient satisfaction of using fitness trackers

Whilst the theory of using fitness trackers in remote prehabilitation is attractive, it is only beneficial if the target population are engaged, willing and able to use the devices for the desired purposes. It is important to acknowledge that the demographics of those undertaking prehabilitation for OG, HPB and LC resections may not be representative of the average and could find the use of these technologies challenging.

There is no current evidence to demonstrate that patients find the use of wearable fitness trackers in prehabilitation acceptable. The benefits of using wearable fitness trackers in prehabilitation will be reduced if compliance with the device is low (i.e., they do not wear them). Therefore, there is a need to assess the acceptability, usability, and user experience of using heart rate trackers in a prehabilitation setting.