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

Abstract

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.

Introduction

Procalcitonin (PCT) is a 13-kDa 116-amino acid prohormone of calcitonin. Its sequence is identical to that of calcitonin (32AA) and katacalcin (21AA). Intact PCT level is elevated in blood of patients with systemic inflammations because of bacterial infections and sepsis a few hours after the occurrence of infection (Beghetti et al., 2003, Brunkhorst et al., 1998, Dandona et al., 1994, Meisner et al., 1996, Müller et al., 2001, Nijsten et al., 2000, Sauerland et al., 2003). Hausfater et al. (2002) reported that PCT was useful as a marker of systemic infection in the emergency department for screening and determination of the prognosis of severely ill patients. Further studies showed that viral infections and autoimmune diseases did not elevate PCT level, but bacterial infection and sepsis did induce high levels of PCT (Delèvaux et al., 2003, Gendrel et al., 1999, Gendrel and Bohuon, 2000, Ugarte et al., 1999).

Several studies have reported the clinical usefulness of measurement of plasma PCT level in patients with infectious diseases, since Assicot et al. (1993) demonstrated the elevation of PCT levels in patients with sepsis in 1993. In 1996, Nylén et al. reported the pneumonitis-associated hyperprocalcitonemia. Hedlund and Hansson, 2000, Brunkhorst et al., 2002 investigated PCT elevation in patients with hospital-acquired or community-acquired pneumonia (CAP), comparing C-reactive protein (CRP) level, and concluded that PCT is more useful for prediction of the prognosis of severe pneumonia than CRP. Korppi et al., 2003, Boussekey et al., 2005, Boussekey et al., 2006) reported that the measurement of PCT is useful for diagnosis and the prediction of the prognosis in pediatric and adult patients with severe CAP in the intensive care unit (ICU). Christ-Crain et al. (2004) suggested that PCT-guided treatment succeeded in reducing the need for antibiotics in patients with lower respiratory tract infection. However, most of the reports above included patients with severe infectious disease only, in particular, those in ICUs and emergency departments for over a decade.

In Japan, almost all patients can be hospitalized even if the CAP is mild by the difference in the health insurance system, where all people buy the medical insurance, which is cheap and covers wide range of diseases and treatments. The people can choose clinics and hospitals anytime as they like. Furthermore, the CAP patients are most usually treated in internal medicine departments even if the patients have severe CAP. We therefore conducted a prospective multicenter study by respiratory physicians having speciality of infectious diseases and by forming a PCT Study Group in the internal medicine departments in 12 Japanese hospitals, and evaluated the usefulness of measurement of plasma PCT in CAP patients ascertained the presence or absence of systemic inflammatory response syndrome (SIRS), whether PCT can discriminate moderate or severe CAP from mild CAP, compared with CRP measurement.