nCD64 index as a prognostic biomarker for mortality in acute exacerbation of chronic obstructive pulmonary disease.

BACKGROOUND

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of mortality and morbidity worldwide. However, there are still no easily obtained biomarkers for prognosis. As a high-affinity Fc receptor, CD64 is an early marker of immune response to bacterial infection, but its role in acute exacerbation of COPD (AECOPD) remains incompletely understood.

OBJECTIVE

We investigated the prognostic role of the neutrophial CD64 (nCD64) index in AECOPD patients.

DESIGN

Retrospective cross-sectional study of all patient admitted between January 2013 to May 2014.

SETTING

Provincial hospitals affiliated with a university.

PATIENTS AND METHODS

Clinical and laboratory data were collected in patients admitted for AECOPD and stable COPD patients, in whom nCD64 index was obtained. A receiver operating characteristics curve was used to determine the optimal cut-off levels for the nCD64 index that discriminated survivors versus nonsurvivors during index hospitalization, and during a post-discharge period of 12 months.

MAIN OUTCOME MEASURES

nCD64 index level.

RESULTS

The white blood cell count, CRP (C-reactive protein (CRP) and PCT (procalcitonin) in AECOPD subjects (n=31) were all significantly higher than in controls (n=18) (P= 3.3 predicted in-hospital mortality with a sensitivity and specificity of 80% and 83%, respectively (area under the ROC=0.887; 95% confidence interval [CI]=0.721-0.972, P < .001). An nCD64 index of 3.3 upon admission as the optimal cut-off level to predict post-discharge mortality had a sensitivity and specificity of 83% and 75%, respectively (area under the ROC=0.842; 95% confidence interval [CI]=0.667-0.948, P < .001).

CONCLUSIONS

An elevated nCD64 index was a reliable prognostic biomarker for both short-term and long-term mortality in patients admitted for AECOPD.

LIMITATIONS

Retrospective design prevented collection of enough evidence to demonstrate infectious origin for COPD in every patient. Unsure whether nCD64 differed between bacterial and viral exacerbation.