Accuracy of Lung Injury Biomarkers in the Initial Investigation of Patients With Suspected Pneumonia

Diagnostic and Prognostic Accuracy of Surfactant Protein D, Krebs Von Den Lungen, and Chitinase-3-like Protein 1 (YKL-40 ) in the Initial Investigation of Patients With Suspected Pneumonia

The aim of this study is to investigate the diagnostic and prognostic value of surfactant protein D, Krebs von den Lungen (KL-6), and Chitinase-3-like protein 1 (YKL-40) in the initial investigation of patients hospitalized with suspected pneumonia. This to improve the diagnosis of pneumonia, contribute to a more rapid and accurate antibiotic treatment, and assess disease severity to predict short-term and long-term mortality in community-acquired pneumonia patients.

Community-acquired pneumonia (CAP) is one of the most common infection diseases in the emergency department (ED). Diagnosis of pneumonia is challenging as symptoms are often weak and nonspecific and the current methods for focal and etiological diagnosis have low sensitivity and specificity and often deliver results after the antibiotic treatment decision has been made.

The abundant and restricted expression of surfactant protein D (SP-D) within the lung makes this protein a specific marker for lung disease. Krebs von den Lungen-6 (KL-6) is expressed in the lung and is a diagnostic and prognostic marker of interstitial lung disease. The inflammatory glycoprotein Chitinase-3-like protein 1 commonly known as YKL-40 is associated with severity of interstitial lung disease. The value of these lung injury markers for diagnosing pneumonia needs further investigation.

The investigators hypothesize that surfactant protein D, Krebs von den Lungen (KL-6), and Chitinase-3-like protein 1 (YKL-40) have an impact on diagnosing, prognosis, and treatment of patients with verified CAP.

The objectives of the study are:

• To investigate the diagnostic accuracy of surfactant protein D, Krebs von den Lungen (KL-6), and Chitinase-3-like protein 1 (YKL-40) in the diagnosis of CAP
• To identify the prognostic value surfactant protein D, Krebs von den Lungen (KL-6), and Chitinase-3-like protein 1 (YKL-40) in relation to adverse events in patients with verified CAP

Inclusion Criteria:

• Suspicion of APN assessed by the receiving physician at the ED

Exclusion Criteria:

• If the attending physician considers that participation will delay a life-saving treatment or patient needs direct transfer to the intensive care unit.
• Admission within the last 14 days
• Verified COVID-19 disease within 14 days before admission
• Pregnant women
• Severe immunodeficiencies: Primary immunodeficiencies and secondary immunodeficiencies (HIV positive CD4 <200, Patients receiving immunosuppressive treatment (ATC L04A), Corticosteroid treatment (>20 mg/day prednisone or equivalent for >14 days within the last 30 days), Chemotherapy within 30 days)