Chronic Obstructive Pulmonary Disease (COPD) affects up to 20% of VA patients and is associated with frequent exacerbations and disability. Physical activity (PA) in COPD may be affected by exacerbations triggered by environmental factors such as air pollution and changes in temperature. Increased use of inhaled short acting beta-agonist (SABA) medications such as albuterol may reflect mild exacerbations or the beginning of a moderate or severe exacerbation. A global positioning system (GPS)-enabled inhaler sensor permits monitoring of location and timing of bronchodilator use. The primary goal of this pilot study was to explore the feasibility recruiting subjects and completion of study procedures, and to obtain data from the GPS-enabled inhaler, the pedometer, and self-reported COPD symptoms and physical activity.
Aim 1: To capture worsening respiratory symptoms and mild exacerbations with a GPS-enabled SABA inhaler device.
Aim 2: To characterize physical activity in patients with COPD using pedometers and a Physical Activity Checklist (PAC).
Aim 3: To examine whether environmental factors (air pollution, temperature, relative humidity) are linked to mild exacerbations as measured by GPS-enabled SABA inhaler device.
We conducted a 12-week longitudinal pilot study of Veterans with COPD at VA Puget Sound. Subjects performed spirometry and completed questionnaires on sociodemographics, medical history, COPD symptoms, and PA. A GPS sensor was placed on subjects' albuterol inhaler to record the time and location of use during the 3-month follow-up. Subjects completed monthly calls regarding exacerbations and hospitalizations, and repeat questionnaires related to their breathing symptoms and PA. A pedometer measured PA for three 7-day periods. During the second month, subjects completed a 7-day PAC, which consisted of 15 common activities.
Patient data was linked to inhaler use data and air pollution and meteorological data. We computed descriptive statistics for all measures. Mean daily inhaler use (puffs/day), mean county-level particulate matter <2.5 micrometers (PM2.5) and ozone (O3) were compared during three mutually exclusive periods: (1) baseline, (2) 3-days prior to exacerbation onset, and (3) during self-reported exacerbations.
We enrolled 35 subjects between December 2011 and January 2014. The device was not compatible with the Combivent (combined albuterol and ipratropium) inhaler, we therefore only used it with albuterol inhalers. 34 subjects completed all study procedures; one subject died of pneumonia unrelated to study procedures and therefore did not complete the study. Subjects were predominantly male (94%) and Caucasian (91%). Mean age was 66 years, with an average of 67.7 pack-years smoking. The mean FEV1 was 45% predicted; 40% were hospitalized and 57% visited the emergency department (ED) at least in the previous year. Of 30 who completed a satisfaction questionnaire, 93% reported being "very" or "somewhat" satisfied with the inhaler device. Of the 28 who reviewed the pedometer, 89% reported overall satisfaction.
Aim 1: The average SABA use recorded by the sensors was 6.5 puffs per day (standard deviation [SD] 5.6). On average, 29.9% [SD 24.1%] of days for each subject had no inhaler use recorded. We could not determine whether days with zero inhaler use reflected days when patients did not need the medications, or if subjects substituted another means of administrating the same medication (i.e. nebulizers or inhaler without the GPS sensor). Hence, days with no recorded inhaler use were excluded from analysis.
The mean baseline puffs per day was 5.4 [SD 4.2]. Twenty-nine patients reported 49 COPD exacerbations: 33 mild (symptom only), 9 moderate (treated with prednisone and/or antibiotics), and 7 severe (ED visit or hospitalization). During mild, moderate, and severe exacerbations the mean puffs per day were 5.8 [SD 5.3], 4.2 [SD 1.8], and 9.9 [SD 4.6], respectively. SABA use changed by
-1.3%[SD 45.3], +2.3%[SD 32.6], and +55.7%[SD 20.7] from baseline to the exacerbation periods.
Aim 2: The mean steps per day measured by the pedometer was 2,472[SD 2,155; n=32], 2,311[SD 1,777; n=28], and 2,045[SD 1,535, n=27], at baseline, week 5, and week 10, respectively. The average number of activities reported on the PAC was 5.2[SD 2.0; n=28] out of 15. The most frequent activities (>50% of days) were walking for >5 minutes, preparing meals, and traveling in a vehicle. The least frequent (<12% of days) were walking in a mall, exercising in a gym, exercising at home, going to medical appointments, and digging in the yard. The correlation between PAC activity count and mean steps per day from the pedometer at week 5 was 0.36[p=0.07].
Aim 3: We linked study data to air pollution data (ozone and PM2.5) from the Environmental Protection Agency and meteorological data (daily temperature and relative humidity) from National Oceanic and Atmospheric Administration in King and Pierce counties in Washington State. Although we planned to exam air pollution at the same location where the inhaler was used, we found that only 22% of inhaler use was associated with a GPS location. The main reason for missing GPS location data was lack of real-time communication between the device and the Bluetooth-enabled phone at the time of the actuation.
The average baseline PM2.5 was 7.21 g/m3. During severe exacerbations, PM2.5 was 31% higher than baseline levels in the 3 days prior to symptom onset (6.39 g/m3 to 8.01 g/m3). The average PM2.5 was 6.81 g/m3 during the first 5 days of severe exacerbations.
97% of participants completed all study procedures, however on average 30% of days had no inhaler use data and 78% of recorded inhaler use was missing GPS location data. We found inhaler use increased during severe exacerbations, suggesting that real-time inhaler use may allow early identification of these events. In addition, higher levels of air pollution (PM2.5) were seen during severe exacerbations. Building on the pilot data, we will use strategies to ensure that the device is measuring all patient SABA use and we will plan not to use the GPS monitoring feature given technological barriers we found. Future research will focus on the effect of pollution to COPD exacerbations and using the inhaler monitoring device to identify early exacerbations in order to help initiate prompt treatment.
- Magzamen S, Oron AP, Locke ER, Fan VS. Association of ambient pollution with inhaler use among patients with COPD: a panel study. Occupational and Environmental Medicine. 2018 May 1; 75(5):382-388.
- Sumino K, Locke ER, Magzamen S, Gylys-Colwell I, Humblet O, Nguyen HQ, Thomas RM, Fan VS. Use of a Remote Inhaler Monitoring Device to Measure Change in Inhaler Use with Chronic Obstructive Pulmonary Disease Exacerbations. Journal of aerosol medicine and pulmonary drug delivery. 2018 Jun 1; 31(3):191-198.
- Sumino K, Locke E, Magzamen S, Thomas R, Gylys-Colwell I, Nguyen HQ, Fan VS. Use of a remote inhaler monitor device to measure change in inhaler use with COPD exacerbations. Poster session presented at: American Thoracic Society Annual International Conference; 2015 May 10; Denver, CO.