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introduction:The patients with Community-Acquired Pneumonia(CAP) could have a higher risk of acute and severe respiratory illness than those without CAP in acute exacerbations of COPD(AECOPD).consequently,early identification of pneumonia in AECOPD is quite important. metholds:62 subjects with AECOPD+CAP and 107 subjects with AECOPD were enrolled from two clinical centers. Clinical parameters and the values of osteopontin (OPN),soluble triggering receptor expressed on myeloid cells-1 (sTrem-1), C-reactive protein (CRP),procalcitonin (PCT),and neutrophil counts (NEU) were measured and compared in AECOPD and AECOPD+CAP on the first day of admission. results:patients with AECOPD+CAP has increased presence of fever, sputum volume,sputum purulence,diabetes mellitus,lower blood pressure, and higher carbon dioxide partial pressure than AECOPD patients(p<0.05).At day1,AECOPD+CAP patients had higher values of NEU,CRP,PCT and OPN,while serum sTREM-1 levels were similar in the two groups. CRP fares best at predicting acute exacerbation of COPD with pneumonia with an area under the curve (AUC) of 0.78, while OPN had similar accuracy with Neu and PCT.the AUC value of OPN,Neu and PCT was 0.61(95% CI 0.53-0.68) , 0.63(95% CI 0.55-0.70) and 0.68(95% CI 0.60-0.75) respectively(p<0.05 for the test of difference). In multivariate analysis, plasma levels of CRP≄15.8 mg/dL at day 1 and sputum purulence were promising predictors of pneumonia in AECOPD. Conclusions:Patients with CAP in AECOPD patients present more clinical parameters and increased biomarker levels but similar short-term outcomes. Combined with plasma CRP level and the clinical characteristic of purulent sputum can be used to predict COPD complicated with pneumonia.