Utility of wearable fitness tracking devices in the assessment of immunoglobulintherapy: A prospective cohort study

Abstract

Executive Summary

Background: Immunoglobulin therapy, administered by subcutaneous or intravenous routes with a wide range of regimen options, is the mainstay of treatment for patients with antibody deficiency, and is also used to treat various neurological and haematological conditions. It is of key importance to be able to demonstrate the benefit of immunoglobulin therapy and to ensure the chosen treatment regimen is optimal. The efficacy of this therapy has been conventionally assessed in a number of ways including the clinical history and examination, blood tests including immunoglobulin trough levels, imaging, microbiology, and validated quality of life tools. Conventional assessment methods are extremely helpful but have some important limitations in that data is obtained intermittently at clinical assessments such as outpatient clinics every six months, imaging every five years, and annual lung function testing. Previous studies have reported that fitness tracker devices (FTDs) are useful in the monitoring of patients with various diseases such as stroke, cancer, and patients undergoing ambulatory surgery. However, it is not known whether these FTDs can be used to monitor the health status and physical activity levels of patients receiving immunoglobulin therapy.

Aim: To assess whether wearable FTDs are useful for assessing the physical activity levels of patients receiving immunoglobulin therapy.

Methods: We conducted a non-randomised longitudinal pilot study over a 1-year period including adult patients receiving immunoglobulin therapy at the Immunodeficiency Centre for Wales (ICW) and other specialist disciplines at the University Hospital of Wales where immunoglobulin therapy is administered and relevant controls. During this first study visit, data about age, sex, medical history, and immunoglobulin therapy (for patients only) were collected using a user-administered questionnaire, and the height and weight of the participant were measured and recorded. Further information relating to the immunoglobulin therapy was obtained from the medical records (patients only). Also, participants were given a FTD and trained how to appropriately use the device. Key metrics recorded by the FTD included date and time, total daily steps, 15-minute heart rate, daily heart rate, daily calories expended, daily metabolic equivalents, daily active time, daily sedentary time, daily distance, and daily sleep time. The data were summarized using descriptive

iv analyses including mean and standard deviation, median and interquartile range, and counts and proportions as appropriate. Compliance to the FTD was assessed using the 15-minute heart rate and wear hours per day and wear days per follow-up period were calculated. Within-subject and between-subject variability was assessed using intraclass correlation and participant-level standard deviation respectively. Correlation between the various physical activity parameters was assessed using repeated measures correlation. The effect of immunoglobulin therapy on physical activity levels was estimated by determining the effect of treatment on the change in the total daily steps, daily sedentary time, daily walk distance, and daily sleep time after 1 year of follow-up.

Results: Of the 33 study participants with available FTD data, it was possible to compute compliance statistics for 27 participants, and these participants were included in the analysis. The mean (±SD) age of the sample was 50 (± 12) years, and there were 13 (48%) females. Also, there were 13 (48%) immunology patients, 7 (26%) neurology patients, 2 (7.4%) haematology patients, and 10 (37%) controls. The proportion of days of the follow-up period when the device was worn varied amongst participants and ranged from 6% to 100%, with the majority (75%) of participants wearing the device for above 60% of the days of the