CRP and bacterial infectious disease: In another study performed by Tanriverdi et al., it has been shown that although serum procalcitonin was better than C-reactive protein for predicting bacterial infection in hospitalized patients with acute exacerbation of COPD, serum procalcitonin was not so reliable in predicting bacterial infection in acute exacerbation of COPD due to sensitivity and specificity of less that 80% (25).