Assessment of physical activity in COPD patients in the stable state and during exacerbation and recovery

INTRODUCTION: Chronic obstructive pulmonary disease (COPD) is an important cause of morbidity and mortality worldwide. It is mainly caused by long-term inhalation of smoke particles. / AIMS: This thesis aims to describe physical activity in COPD patients in the stable state, during exacerbation and subsequent recovery, and the factors which influence these phases especially those that are environmental. / METHODS: Physical capacity and activity was assessed with a variety of methods and devices. I chose to use a six minute walking distance test and an accelerometer (SenseWear) device which estimates energy expenditure. A number of clinical factors were also assessed at the stable, exacerbation and recovery states through use of questionnaires (COPD assessment test, Hospital Anxiety and Depression Scale and Functional Assessment of Chronic Illness Therapy-Fatigue Scale). To prospectively collect data leading up to an exacerbation I used a pedometer which was validated against the SenseWear device and manual counting. Patients recorded their step counts on a total or 16,478 days- an average of 267 days per patient (range 29-658) when stable, at exacerbation presentation (day 0) and at recovery visits (days 3, 7 and 14 days thereafter). At the same time, patients recorded any increase over usual stable symptoms per day, time spent outdoors and Peak Expiratory Flow (PEF). / RESULTS: The 73 COPD patients (70% male) had a mean (±SD) age 71.1 (±8.7) years and FEV1 52.9 (16.5) % predicted. Results showed that daily step count in community treated exacerbations returns to pre-exacerbation levels within 3–4 days, with those patients experiencing the greatest reduction in step count taking longer to recover, and patients suffering frequent exacerbations experiencing a faster decline in activity. I also observed that patient activity in the stable state was inversely associated with high levels of atmospheric pollution. Moreover patient activity was markedly lower during the weekends and during cold weather. At exacerbation, changes in exercise capacity, muscle strength and energy expenditure were related to disease severity, changes in the perception of fatigue and exacerbation frequency. The results also indicated that prior pulmonary rehabilitation may have a lasting benefit in mitigating this reduction in physical activity, and that possibly change in physical activity is associated with changes in systemic inflammatory markers at exacerbation. / CONCLUSIONS: Maintenance of physical activity is important in COPD. Strategies that encourage activity when patients are unwell (such as personalised early Pulmonary rehapilation) or unwilling to take exercise (such as during the winter or weekends) need to be devised to prevent de-conditioning at these times. Physical activity and exercise capacity are reduced during COPD exacerbation recovery and may be linked to increased systemic inflammation and fatigue. Frequent exacerbators should be particularly targeted for exercise programs. Schemes to reduce levels of atmospheric pollution should be further encouraged