Bidirectional Associations Between Physical Activity, Sedentary Behavior, and Daily Symptoms in Patients With Chronic Obstructive Pulmonary Disease: Longitudinal Observational Study.

Background: Questionnaire-based symptom assessment may introduce recall bias and lacks bidirectional exploration. This is particularly relevant, given the unclear direction of the associations between physical activity (PA), sedentary time (ST), and symptoms in patients with chronic obstructive pulmonary disease (COPD). Understanding these associations could inform symptom management strategies and improve patient quality of life. Objective: This study aimed to investigate the direction of the association between PA, ST, and symptoms in patients with COPD using accelerometry and ecological momentary assessment (EMA). Methods: A subsample from the FAntasTIGUE study answered 8 randomly timed EMA questionnaires daily for 5 days. Ten symptoms were rated on a 7-point Likert scale: "I feel relaxed, short of breath, energetic, cheerful, insecure, irritated, satisfied, anxious, tired, and mentally fit." Concurrently, step count and ST were measured using the ActiGraph GT9X Link placed on the right hip. Step count and ST 15 and 30 minutes pre- and post-EMA were used in multilevel models, controlled for pre-EMA steps and ST, and the previous EMA score. Significant confounders were used as covariates, and patient ID was used as random intercept. Results: Thirty-four patients (19/34, 56% men, mean age 66, SD 7 years; forced expiratory volume in 1 second 52±20% predicted; 1035 EMA responses) were included. Feeling more relaxed was associated with a higher step count 15 minutes post-EMA (β=5.1; 95% CI 0.9 to 10.1; P=.046). Conversely, higher step count 15 and 30 minutes pre-EMA was associated with feeling less relaxed (β=-5.2×10-4; 95% CI -9.7×10-4 to -7.0×10-5; P=.02; and β=-3.2×10-4; 95% CI -5.6×10-4 to -7.9×10-5; P=.009), more short of breath (β=8.5×10-4; 95% CI 4.7×10-4 to 1.2×10-3; P<.001; and β=4.6×10-4; 95% CI 2.6×10-4 to 6.6×10-4; P<.001), and tired (β=5.1×10-4; 95% CI 7.2×10-5 to 9.4×10-4; P=.02; and β=2.9×10-4; 95% CI 5.3×10-5 to 5.2×10-4; P=.02). Higher ST 15 and 30 minutes pre-EMA was associated with feeling more anxious (β=1.7×10-4; 95% CI 1.7×10-5 to 3.2×10-4; P=.03; and β=8.5×10-5; 95% CI 2.5×10-6 to 1.7×10-4; P=.04). Conclusions: A bidirectional association of feeling relaxed with PA was found in patients with COPD. Higher step count was related to feeling more short of breath and tired, whereas higher ST was associated with heightened anxiety.