Subgroup analysis of symptoms and their effect on functioning, exercise capacity, and physical activity in patients with severe chronic obstructive pulmonary disease

Background: Little is known about symptom clusters and their effect on outcomes in people with chronic obstructive pulmonary disease (COPD). Purposes: To determine whether subgroups of patients with COPD could be identified by symptom ratings, whether they differed on selected demographic and clinical characteristics, and whether they differed on functioning, exercise capacity, and physical activity. Method: Subjects with severe COPD ( n=596) were drawn from the National Emphysema Treatment Trial dataset. Data were drawn from questionnaires and clinical measures. Results: Two subgroup clusters emerged from four symptoms. Mean age and the proportion of participants with higher education, higher income levels, and using oxygen at rest were significantly different between subgroups. Participants with high levels of symptoms had lower functioning and decreased exercise capacity. Symptom cluster subgroups were significantly associated with social functioning. Conclusion: These findings suggest that screening for high levels of symptoms may be important in patients with severe COPD.