Evaluation of reliability of MYZONE MZ-3 Heart Rate Monitor: A study for the Future of Telephysiotherapy for Preoperative Prehabilitation in Cancer Patients.
TELEMEDICINE and e-HEALTH 2017;23(4):1-5 doi:10.1089/tmj.2016.0138
Presented by: Dr C Francis
Pre-operative optimisation programs seek to implement a series of interventions to improve and enhance recovery after major surgery. An important aspect of this is the use of exercise programs. The Authors of this paper suggest a major barrier to successful completion of these programs could be inaccessibility of in-hospital supervised exercise programs. There is an increasing abundance of wearable technology, however the accuracy and reliability of commercially available Heart Rate monitors is variable.
Design & Setting
Small, prospective, pilot experiment at single centre in Australia. Small sample (n=7) of young, healthy volunteers without significant medical history and in normal sinus rhythm recruited. Asked to perform increasing intensity effort on exercise bike wearing the MYZONE MZ-3 Heart rate monitor and a clinical 3 lead ECG system. Paired HR measurements to be taken and compared statistically using a Bland Altman plot
Seven young physically active, healthy individuals in normal sinus rhythm (mean age 29.7 years; 5 female, 2 male)
Asked to complete an exercise on static bike of increasing intensity whilst wearing both clinical 3 lead ECG and MYZONE MZ-3 HR monitor.
1,983 data points collected. Of which 55 data points unpaired as loss of contact with MYZONE MZ-3 HR Monitor. Only paired data sets included. Significantly 5 of the 7 participants had their collected data received out of sync, reported as being due to a failure to manually synchronise time on both MYZONE MZ-3 HR and ECG monitors pre test. Authors included this data after retrospective correction of data by aligning out of sync data, moving the sample to the left by 20 seconds. The authors feel this adjustment of data unlikely to cause any clinically significant effects on results.
Using a Bland-Altman plot able to demonstrate a bias of 0.4bpm, and adjusted 95% limits of agreement (95% LOA) to be -4.5 to +5.3 bpm. And a percentage error [95%LOA/mean HR] of 3.6%
MYZONE MZ-3 has an acceptable level of reliability for use in healthy volunteers performing exercise across a wide range of HR. Further studies using a similar methodology are required to validate the use in patients presenting for cancer surgery.
- Prospective study
- Appropriate use of statistical analysis to assess reliability and precision of HR monitor.
- This study had a very small sample size, of healthy, young volunteers. Therefore, this cannot be extrapolated to those awaiting cancer surgery.
- None of the participants were noted to have any features which may have produced inaccuracy such as arrythmias, obesity, tremor, pacemakers.
- A static bike was used and so there was minimal movement artifact.
- 55 data sets were not paired due to the loss of contact with HR monitor and are not included in reliability figures.
- Perhaps most significantly there is retrospective alteration of the data collected from 5 out of the 7 participants. Whilst the authors claim this is unlikely to have caused significant effects to the results I fail to see how an experiment with aims of assessing precision and accuracy of a piece of equipment can be deemed safe when 5/7 of data sources have been altered retrospectively.
- In addition, there was no structured exercise protocol used and no examination of the cost benefit of the intervention.
- Limited at present.
- Could be deemed a starting point for a project requiring significant further examination.
Potential for impact
Increasing numbers of wearable technologies are available and being used in the community. There is much competition between devices and price points are changing dramatically as with most tech products. The use of these products could be of great use in prehabilitation of pre-operative patients. There is much scope for further investigation and cost benefit analysis of this and similar products.