Summary
Background
Viral or bacterial upper respiratory infections are the most common cause of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Based on available data, no reliable parameter has been presented to distinguish between bacterial and nonbacterial exacerbations. Therefore, we compared the diagnostic value of procalcitonin (PCT) level, which is a newer marker for predicting bacterial infections in patients with AECOPD, to routine parameters such as C-reactive protein (CRP) levels and the neutrophil/lymphocyte (N/L) ratio.
Methods
This study included all consecutive patients who were admitted for a diagnosis of AECOPD between January 1 and March 31, 2014. PCT, CRP, and the N/L ratio were assessed in addition to cultures from tracheal aspirates or sputum on the first day of admission. Patients with a pneumonic infiltration on chest radiographs, or an extrapulmonary infection focus, or whose blood samples were not obtained for PCT and/or CRP at the same time as sputum culture were excluded from the study.
Results
A total of 77 patients were included with a mean age of 71.7 ± 9.5 years. Bacteria were isolated in 37.4 % of the patients. Mean PCT levels were significantly higher in patients with positive sputum cultures than in patients with negative sputum cultures. The cut-off values for PCT, CRP, and the N/L ratio for predicting a bacterial infection were 0.40 ng/mL, 91.50 mg/L, and 11.5, respectively; sensitivity was 61, 54, and 61 % respectively; specificity was 67, 52, and 58 %, respectively; and the area under the curve (AUC) values were 0.64, 0.52, and 0.58, respectively. The AUC value of PCT was significantly better for predicting bacterial infection compared with the CRP level or the N/L ratio (p = 0.042).
Conclusion
PCT was better than CRP and the N/L ratio for predicting a bacterial infection in hospitalized patients with AECOPD. However, we find PCT not so reliable in predicting bacterial infection in AECOPD due to sensitivity and specificity of less than 80 % and a low AUC value.
Zusammenfassung
Hintergrund
Virale oder bakterielle Infektionen des oberen Respirationstraktes sind die häufigste Ursache einer akuten Exazerbation einer chronisch obstruktiven Lungenerkrankung (COPD). Bis jetzt ist kein verlässlicher Parameter bekannt, der in der Lage ist, zwischen bakteriellen und nicht-bakteriellen Exazerbationen zu unterscheiden. Wir haben daher den diagnostischen Wert der Konzentrationen von Procalcitonin (PCT), einem neueren Marker zur Vorhersage bakterieller Infektionen bei Patienten mit COPD, mit dem der herkömmlichen Routineparameter, wie dem C-reaktivem Protein (CRP) und dem Neutrophilen/Lymphozyten (N/L) Quotienten, verglichen.
Methoden
Diese Studie schloss alle konsekutiven Patienten ein, die mit der Diagnose einer COPD zwischen 1. Jänner und 31. März 2014 aufgenommen waren. PCT, CRP und die N/L Quotienten wurden zusätzlich zu Kulturen von Aspiraten aus der Trachea oder von Sputa am Aufnahmetag erhoben. Patienten mit einem Lungeninfiltrat oder einem extrapulmonalen Infektionsherd und/oder deren Blutproben nicht am selben Tag wie die Sputum Kulturen abgenommen waren, wurden aus der Studie ausgeschlossen.
Ergebnisse
Siebenundsiebzig Patienten mit einem mittlerem Alter von 71,7 ± 9,5 Jahren wurden in die Studie aufgenommen. Bei 37,4 % der Patienten konnten Bakterien isoliert werden. Die mittleren PCT Werte waren bei den Patienten mit positiven Sputum Kulturen signifikant höher als bei denen mit negativen Kulturen. Die Grenzwerte für die PCT, CRP und N/L Quotienten Werte zur Vorhersage eines bakteriellen Infektes lagen bei 0,40 ng/mL, 91,50 mg/L, und 11,5. Die Sensitivität war bei 61, 54, und 61 % – die Spezifität bei 67, 52, und 58 %, die Flächen unter der Kurve (AUC) 0,64, 0,52, and 0,58. Die AUC der PCT Werte war bei der Vorhersage von bakteriellen Infekten im Vergleich zu den CRP Werten und den N/L Quotienten signifikant besser (p = 0,042).
Schlussfolgerung
Bei Patienten mit COPD war das PCT bei der Vorhersage von bakteriellen Infekten besser als das CRP beziehungsweise die N/L Quotienten. Wir sind allerdings der Meinung, dass PCT kein sehr verlässlicher Parameter in der Vorhersage von bakteriellen Infekten ist, da sowohl die Spezifität als auch die Sensitivität unter 80 % liegen, und da auch die AUC niedrig ist.
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Tanrıverdi, H., Örnek, T., Erboy, F. et al. Comparison of diagnostic values of procalcitonin, C-reactive protein and blood neutrophil/lymphocyte ratio levels in predicting bacterial infection in hospitalized patients with acute exacerbations of COPD. Wien Klin Wochenschr 127, 756–763 (2015). https://doi.org/10.1007/s00508-014-0690-6
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DOI: https://doi.org/10.1007/s00508-014-0690-6