Procalcitonin is not an independent predictor of 30-day mortality, albeit predicts pneumonia severity in patients with pneumonia acquired outside the hospital

Takanori Akagi,Kentaro Watanabe,Hiroyuki Miyazaki,Masaki Fujita,Nobuhiko Nagata,Kenji Wada,Satoshi Takeda,Yuji Yoshida,Taishi Harada

doi:10.1186/s12877-018-1008-8

Abstract

BackgroundProcalcitonin (PCT) is a useful marker for pneumonia. However, its clinical usefulness in elderly patients has not been studied extensively. This study aimed to assess the relationship between PCT and prognosis and pneumonia severity in elderly patients with pneumonia acquired outside the hospital.MethodsData considered relevant to pneumonia severity and prognosis were retrospectively obtained from clinical charts of all patients with pneumonia who were admitted to our hospital from 2010 to 2017. The primary outcome was 30-day mortality in elderly patients (aged ≥75 years), and the relationship between PCT levels and pneumonia severity, as determined by the pneumonia severity index (PSI) was also examined.ResultsData were collected from 667 patients, of which 436 were elderly patients. Multivariate and receiver operating characteristic curve analysis revealed that albumin, body mass index, and PSI class rather than PCT are important factors related to 30-day mortality in elderly patients. PCT was also not an independent prognostic factor in younger patients. PCT levels significantly differed by pneumonia severity (mild, moderate, and severe) in both younger (p < 0.001) and elderly (p < 0.0001) patients, with levels increasing as severity increased. In contrast, C-reactive protein (CRP) levels and white blood cell counts did not significantly differ by pneumonia severity in younger and elderly patients. A subgroup analysis focused on Streptococcus pneumoniae pneumonia revealed that PCT levels differed by severity in elderly patients (p = 0.03), with levels increasing as severity increased.ConclusionPCT was not an independent predictor of 30-day mortality in both of elderly and younger patients. PCT levels, but not CRP levels, significantly increased with increasing pneumonia severity in younger and elderly patients, although the degree of increase tended to be lower in elderly patients compared to younger patients for the same severity. PCT levels also significantly increased with increasing pneumonia severity in elderly patients with Streptococcus pneumoniae pneumonia.

Highlights

Procalcitonin (PCT) is a useful marker for pneumonia
Data on admission considered related to pneumonia severity and prognosis were examined, including age, sex, category of pneumonia occurring outside the hospital (CAP or healthcare-associated pneumonia (HCAP)), pneumonia severity index (PSI) class, comorbidities, body mass index (BMI), serum albumin, C-reactive protein (CRP), PCT and blood urea nitrogen (BUN) levels, and white blood cell (WBC) count
No of patients died within 30 days Male / female Age(years) Community-acquired pneumonia (CAP) / HCAP PSI class I II III IV V BMI(kg/m2) Albumin(g/dL) Procalcitonin(ng/mL) WBC(/mm3) CRP(mg/dL) BUN(mg/dL) Comorbidity Charlson comorbidity index 0 1 2 3 4 5 6 Chronic lung disease Diabetes mellitus Dementia Cerebrovascular disease Chronic heart failure Malignancy Kidney disease Liver disease Pathogen Streptococcus pneumoniae Haemophilus influenzae Klebsiella pneumoniae Escherichia coli Pseudomonas aeruginosa Moraxella catarrhalis Methicillin-sensitive Staphylococcus aureus (MSSA) Methicillin-resistant Staphylococcus aureus (MRSA) Serratia marcescens Enterococcus faecalis Stenotrophomonas maltophilia

Summary

Introduction

Procalcitonin (PCT) is a useful marker for pneumonia. Its clinical usefulness in elderly patients has not been studied extensively. This study aimed to assess the relationship between PCT and prognosis and pneumonia severity in elderly patients with pneumonia acquired outside the hospital. Representing the large majority of cases of CAP admitted to acute-care hospital wards, are often excluded from clinical studies due to the possible presence of multiple confounders. Pneumonia occurs mainly in the elderly, the usefulness or clinical significance of PCT in these patients has not been studied extensively. While some studies have reported that PCT levels do not elevate according to the severity in elderly patients [8, 9], others have argued that PCT is useful for predicting the severity of CAP [10, 11]

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