P50 Use of accelerometers to compare physical activity levels in participants with asthma grouped by body mass index and asthma severity

Background: Patients with asthma may find it impacts their ability to be physically active. Physical activity (PA) has been demonstrated to be lower in asthmatics compared to healthy controls. Obesity is commonly linked with difficult-to-control asthma and can worsen outcomes. At least 150 minutes of moderate physical activity (PA) per week is recommended for all adults by the World Health Organisation. We aimed to compare PA levels in patients with difficult-to-control asthma and body mass index (BMI) ≥25 kg/m2 (DOW group) and two control groups with mild-moderate asthma, one with BMI <25 kg/m2 (MHW group) and one with BMI ≥25 kg/m2 (MOW group).

Methods: This cross-sectional study used 7-day recordings from wrist-worn accelerometers to compare PA between groups. We recorded inactive time, light (LPA) and moderate-vigorous physical activity (MVPA). We also measured novel metrics: intensity gradient (IG) reflecting PA intensity, and average acceleration (AA) reflecting PA volume. Parameters were compared across groups using ANOVA testing for normally distributed data and Kruskall-Wallis for skewed data. Correlation analysis explored associations between PA parameters and asthma measures. As AA was most closely correlated with asthma measures, we compared the highest and lowest AA quartiles using unpaired t and Mann-Whitney U tests, depending on normality.

Results: 75 participants were recruited, 25 per group. Inactive time was significantly higher (p<0.001), and LPA (p=0.007), MVPA (p<0.001), IG (p<0.001) and AA (p<0.001) all significantly lower in DOW group compared to MHW and MOW groups, even after adjusting for age and BMI. For AA, notable correlations included beclometasone diproprionate-equivalent dose of inhaled corticosteroid (r=-0.591, p<0.001), asthma-related quality of life score (r=0.531, p<0.001) and six-minute walk distance (r=0.719, p<0.001). Highest and lowest AA quartiles revealed significant differences in 14 of 21 asthma outcomes including the above, and pre-bronchodilator forced expiratory volume in 1 second, 6-point asthma control questionnaire and BMI.