Background Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are characterised by an acute worsening of symptoms beyond the normal day-to-day variability. Pneumonic episodes, confirmed by new chest X-ray (CXR) infiltrates, are common in patients with COPD but are difficult to distinguish in primary care from non-pneumonic exacerbations. It is uncertain whether AECOPD and pneumonic episodes in COPD patients are distinct clinical events in terms of aetiology and/or response to oral therapy. We performed a longitudinal study to characterise these events and to determine clinically meaningful differences associated with CXR changes in the outpatient setting.
Methods The Acute Exacerbation and Respiratory Infections in COPD (AERIS) study is a longitudinal epidemiological study to assess how changes in the COPD airway microbiome contribute to the incidence and severity of AECOPD. Patients with moderate to very severe COPD aged 40–85 years were followed monthly for 2 years, and reviewed within 72 h of onset of symptoms of AECOPD. We compared markers of systemic and airway inflammation between pneumonic AECOPD characterised by new CXR infiltrates, and non-pneumonic AECOPD, in a sub-cohort of 36 patients.
Results In the first year of study participation 122 exacerbations were recognised of which 120 had a CXR performed. Of these, 20 (16.7%, n = 12 patients) were identified as having new radiographic infiltrates. Statistically significant differences occurred in mean white blood cell count, blood neutrophil count, C-reactive protein, fibrinogen and sputum percentage neutrophil count between those AECOPD with new CXR infiltrates and those without (Table 1). Furthermore, there was a trend towards more severe symptom scores with pneumonic episodes using the EXACT-PRO score (p = 0.057).
Conclusion Pneumonic episodes are common in the context of clinical events presenting as outpatient AECOPD. The profile of airway and systemic inflammation is greater during these events than those without CXR changes. Understanding whether the biology and clinical course of these events is distinct from other exacerbations is key, particularly as patients are encouraged to self-manage based on symptom changes alone. Further study of the AERIS cohort will investigate links between aetiology, outcomes and prognostic markers at exacerbation including radiological and clinical indices.