Comparison of usefulness of plasma procalcitonin and C-reactive protein measurements for estimation of severity in adults with community-acquired pneumonia

Although procalcitonin (PCT) measurement has been performed in patients with infectious diseases, there are few reports on its usefulness in community-acquired pneumonia (CAP) associated with systemic inflammatory response syndrome (SIRS). We investigated 88 patients who visited the internal medicine departments of Nagasaki University Hospital, Nagasaki, Japan, and its 11 affiliated hospitals in Japan because of CAP with or without SIRS. Of the 88 patients, 15 (17.0%), 43 (48.9%), and 30 (34.1%) were judged to have severe, moderate, and mild CAP, respectively. Although 87 patients (98.9%) had C-reactive protein (CRP) levels exceeding 0.3 mg/dL, only 30 patients (34.1%) had PCT levels more than 0.5 ng/mL. In addition, 93.3% (28/30) of patients with mild CAP had negative PCT, and 48.3% (28/58) of patients positive for PCT had moderate or severe CAP. Our findings suggest that PCT level might be more useful for estimating CAP severity than CRP level at the 1st visit.