Eosinopenia as a marker of mortality and length of stay in patients admitted with exacerbations of chronic obstructive pulmonary disease

Background and objective: Blood eosinopenia has long been known as a marker of acute infection, and has recently been shown to be a better predictor of sepsis than CRP in critically ill patients. This study examines the usefulness of eosinopenia (< 0.04), for predicting the severity of exacerbations of COPD using inpatient mortality and length of stay as markers of severity. Methods: Retrospective review of the case-notes of patients admitted with an exacerbation of COPD from March 2007 to April 2008. Patients with radiographic evidence of pneumonia and those having steroids in the previous week were excluded. Data were collected for age, length of stay, pH, WCC and mortality. Results: Sixty-five patients fulfilled the inclusion criteria, 42 with a normal eosinophil count and 23 with eosinopenia. No significant differences were seen between the two groups' age, total WCC and admission pH. However, significant differences were seen in mortality (4/23 (17.4%) vs 1/42 (2.4%), P = 0.049) and length of stay (8 vs 5 days, P = 0.005) when the eosinopenia group compared with those with normal eosinophils. Conclusions: The eosinophil count might be a useful marker of severity inpatients admitted with an exacerbation of COPD independent of the WCC and pH. As it is routinely given in the full blood count in all patients admitted to hospital, there is no extra cost for this beneficial test.