Procalcitonin vs C-reactive protein as predictive markers of response to antibiotic therapy in acute exacerbations of COPD

Chest. 2010 Nov;138(5):1108-15. doi: 10.1378/chest.09-2927. Epub 2010 Jun 24.


Background: Rational prescription of antibiotics in acute exacerbations of COPD (AECOPD) requires predictive markers. We aimed to analyze whether markers of systemic inflammation can predict response to antibiotics in AECOPD.

Methods: We used data from 243 exacerbations out of 205 patients from a placebo-controlled trial on doxycycline in addition to systemic corticosteroids for AECOPD. Clinical and microbiologic response, serum C-reactive protein (CRP) level (cutoffs 5 and 50 mg/L), and serum procalcitonin level (PCT) (cutoffs 0.1 and 0.25 μg) were assessed.

Results: Potential bacterial pathogens were identified in the majority of exacerbations (58%). We found a modest positive correlation between PCT and CRP (r = 0.46, P < .001). The majority of patients (75%) had low PCT levels, with mostly elevated CRP levels. Although CRP levels were higher in the presence of bacteria (median, 33.0 mg/L [interquartile range, 9.75-88.25] vs 17 mg/L [interquartile range, 5.0-61.0] [P = .004]), PCT levels were similar. PCT and CRP performed similarly as markers of clinical success, and we found a clinical success rate of 90% in patients with CRP ≤ 5 mg/L. A significant effect of doxycycline was observed in patients with a PCT level < .1 μg/L (treatment effect, 18.4%; P = .003). A gradually increasing treatment effect of antibiotics (6%, 10%, and 18%), although not significant, was found for patients with CRP values of ≤ 5, 6-50, and > 50 mg/L, respectively.

Conclusions: Contrary to the current literature, this study suggests that patients with low PCT values do benefit from antibiotics. CRP might be a more valuable marker in these patients.

Trial registration: NCT00170222.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Anti-Bacterial Agents / therapeutic use*
  • Biomarkers / blood
  • C-Reactive Protein / metabolism*
  • Calcitonin / blood*
  • Calcitonin Gene-Related Peptide
  • Doxycycline / therapeutic use*
  • Female
  • Follow-Up Studies
  • Glycoproteins
  • Humans
  • Male
  • Nephelometry and Turbidimetry
  • Protein Precursors / blood*
  • Pulmonary Disease, Chronic Obstructive / blood*
  • Pulmonary Disease, Chronic Obstructive / drug therapy
  • Pulmonary Disease, Chronic Obstructive / physiopathology
  • Recurrence
  • Retrospective Studies
  • Treatment Outcome


  • Anti-Bacterial Agents
  • Biomarkers
  • CALCA protein, human
  • Glycoproteins
  • Protein Precursors
  • Calcitonin
  • C-Reactive Protein
  • Calcitonin Gene-Related Peptide
  • Doxycycline

Associated data