Changing Pattern of Sputum Cell Counts During Successive Exacerbations of Chronic Obstructive Pulmonary Disease

AbstractBackground: Chronic Obstructive Pulmonary Disease exacerbations are associated with worsening of airway inflammation, the nature of which may be neutrophilic, eosinophilic, or both.Objective: The primary objective was to examine the cellular nature of airway inflammation in successive COPD exacerbations in order to ascertain if they changed in individual patients. The secondary objective was to estimate the relative risk indicating the extent to which a particular type of exacerbation changed as a function of the most recent exacerbation. Design: This was a retrospective survey performed on a computerised sputum cell count database of a referral respiratory service in Hamilton, Canada. Recurrent event analyses were used to model the incidence of exacerbations and subtypes of exacerbations. Results: 359 patients and 148 patients had sputum examined during stable condition and during exacerbations, respectively. It was found 65 patients had sputum examined during both situations. The exacerbations w...