Rationale Chronic Obstructive Pulmonary Disease (COPD) patients with frequent exacerbations are recognised as a distinct clinical phenotype. There are calls for studies to investigate treatment responses within clinical phenotypes of COPD. Pulmonary rehabilitation is considered one of the most beneficial treatments for COPD including a reduction in risk of exacerbations. However, clinical outcomes of pulmonary rehabilitation between frequent and infrequent exacerbators remain unclear. The aim of this study was to examine responses to pulmonary rehabilitation in frequent and infrequent exacerbators of COPD.

Methods 73 mild to very severe COPD patients (FEV₁ pred, 51%±18%) were enrolled on to community pulmonary rehabilitation. COPD patients were categorised as frequent (2 or more exacerbations (requiring treatment) in the past 12 months) or infrequent exacerbators (1 or less exacerbations). The primary outcome was successful completion of pulmonary rehabilitation defined as attending a minimum number of 12 sessions. The following outcomes were analysed for patients who completed initial and final assessment: incremental shuttle (ISWT) and endurance shuttle walk tests (ESWT), chronic respiratory disease questionnaire (CRQ), and hospital anxiety and depression scale (HADS).

Results Fewer frequent exacerbators completed pulmonary rehabilitation compared to infrequent exacerbators (45% vs 69%, p=0.048). Both groups experienced statistically significant improvements in ISWT (p<0.001) and ESWT (p<0.001) performance, but no group ×time interactions (ISWT, p=0.198; ESWT, p=0.453) or group differences were observed (ISWT, p=0.911; ESWT, p=0.688). There was a significant improvement in disease specific quality of life (CRQ (all domains), p<0.05; depression, p=0.025) with pulmonary rehabilitation but no significant effects were observed with anxiety (p=0.138). No significant effects of group or group ×time interaction on disease specific quality of life domains, anxiety (p=0.920; p=0.298) or depression (p=0.808; p=0.644) were observed.

Conclusion Frequent exacerbators are less likely to successfully complete pulmonary rehabilitation, but those who complete appear to experience similar improvements to infrequent exacerbators. Pulmonary rehabilitation should be encouraged in both frequent and infrequent exacerbators of COPD, but additional support or targeted interventions may be required for frequent exacerbators to complete the programme.