Role of home telemonitoring of lung function using the forced oscillation technique (FOT) in asthma during down-titration of treatment

In a pragmatic, observational study, we will evaluate the ability of day-to-day variations in lung function measured by the forced oscillation technique (FOT), to predict occurrence of exacerbations (primary outcome) and changes in symptom control (secondary outcome) in asthma, during physician-indicated down-titration of treatment according to Australian guidelines. Potential patients are identified during routine clinic visits (treated as Visit 1) based on their clinical status (well-controlled symptoms and on maximal ICS treatment dose) and consideration for down-titration of treatment by their treating physician according to Australian guidelines. Patients who are eligible for the study will be asked if they are willing to participate in home monitoring, and have their baseline health status, symptoms (ACQ-5) and standard respiratory function (spirometry and lung volumes) data collected as part of their standard clinical assessment. Patients willing to participate in the study will have a FOT device installed in their homes by a study investigator (a respiratory researcher familiar with FOT), who will train them to make unsupervised FOT self-measurements during a 30-45 minute visit. Participants will be monitored for an initial (approximate) 8-week baseline period during which existing treatment will be unchanged unless clinically warranted. Following this, physician-indicated step-down of treatment will be initiated, to 50% of the patient’s regular maintenance ICS dose for 8 weeks, with a further 50% step-down or switch from twice- to once-daily treatment after another 8 weeks if clinically indicated, consistent with recommendations in Australian guidelines. For most patients, these reductions in ICS dose will be achieved with commercially available combination ICS/LABA formulations; for patients using separate ICS and LABA inhalers at entry (e.g. those whose ICS is ciclesonide or beclomethasone), the dose reductions will be achieved with commercially available ICS formulations, with the same LABA dose continued. Monitoring will cover a total period of approximately 24 weeks (8 weeks of baseline period + 16 weeks prediction phase). During this time, any treatment decisions/changes will be made solely by the treating physician based on the patient’s clinical need. Throughout the entire study period, patients will self-record symptoms and FOT once daily in the morning, followed by a PEF measurement, before taking their maintenance treatment. Patients will also have weekly telephone interviews where questionnaire data (ACQ), symptoms and exacerbations will be captured. Details of measurements performed during home monitoring can be found below. It is expected that patients will come in for further visits for clinical assessment and standard respiratory function testing whenever clinically indicated: prior to the prediction phase (Visit 2, at which treatment step-down is confirmed), midway during the prediction phase (Visit 3, at which need for further treatment step-down is evaluated), and at the end of the study (Visit 4). Treatment Changes Should a treating physician deem that a change in treatment is warranted during any phase, e.g. due to loss of control or exacerbations, patients will not need to be withdrawn, but will continue daily monitoring as per usual. FOT Measurements FOT home monitoring devices (Resmon Pro DIARY, Restech srl, Milan, Italy) will be set up at the patient’s home at enrolment. The technical specifications for the device have been previously published [Dellaca et al, Physiol Meas (2010) 31:N11–N24]. During measurement, a loudspeaker generates 5-11-19 Hz forced oscillations delivered to the airway opening via an antibacterial filter/mouthpiece assembly. The resulting airway opening pressure and flow are measured and used to calculate respiratory resistance. These can be further partitioned into an inspiratory and expiratory component. Patients will be instructed to make a 1- to 2-min measurement (for a minimum of 10 technically acceptable breaths) each day during normal breathing whilst seated, wearing a nose clip and with cheeks supported. De-identified FOT data will be uploaded daily via the 4G mobile internet network to encrypted servers, where they will be checked for quality by a research assistant. PEF Measurements Following FOT, patients will also monitor their PEF using a digital spirometer using standardised protocol, i.e. highest of 3 blows. Patients who currently make PEF measurements will be asked to use the digital spirometer, and they will be shown how to extract the results for their normal monitoring. Patients who have never made PEF measurements before will be instructed on how to do them during the home visit. Symptom and Exacerbation Measurements Daily symptoms will be entered into an electronic diary prior to the FOT measurement via the same device interface. We will use an adaptation of symptom diary used in a recently published trial [Virchow et al, Jama (2016) 315:1715-25], from which the definition of moderate exacerbations was derived. In addition, study personnel will contact the patient weekly to record treatment changes, symptoms (ACQ-5), medications and asthma-related healthcare utilisation, to capture changes in asthma control and/or exacerbations. During this time, patients will continue to see their usual healthcare provider when necessary.