CRP and Thoracic Emergency Ultrasound in Pneumonia
Condition: Difference, Individual; Community-acquired Pneumonia; Ultrasound
MeSH terms: Pneumonia; Emergencies
Study type: Observational

Summary: 
      This preliminary study investigates in patients with possible clinical diagnosis of
      pneumonia, clues and biomarker assessed at Emergency Department (ED) triage, potentially
      predicting detection of lung consolidation by Thoracic-ultrasound (TUS) and/or by
      Chest-X-Rays. Cough and high admission CRP levels will be defined according to the cutoff
      defined by ROC analysis, will be challenged if independently associated with TUS lung
      consolidation detection High level of the chosen biomarker, and any of the considered
      symptoms, in otherwise not extremely critical patients (CURB65≤3), should prompt to immediate
      confirm by TUS, during the physical examination. This may limit the need of further
      radiological investigations allowing targeted workup.
    

Detailed description: 
      Chest-X-Rays (CXR), Computerized Tomography (CT) or Thoracic Ultrasound (TUS) provide images
      deemed consistent with acute lung consolidation and suitable to confirm the diagnosis of
      community acquired pneumonia (CAP). Patients which may be affected by CAP are many , but
      diagnosis is not straightforward because we are managing "a disease characterized by educated
      guesswork" . Comprehensive imaging workup may be not regularly affordable in busy emergency
      rooms. Point-of-care TUS allows reliable diagnosis of lung consolidation and of pleural
      effusion. Regretfully, adequate TUS expertise is more warranted than actually available in
      most medical departments. Even not specifically investigated, a delay or even an impairment
      of appropriate TUS or CXR evaluation for several patients may occur due to time- or
      resource-limiting factors.

      Clinical clues of lung consolidation are many. Key symptoms are cough, fever, chest pain and
      dyspnea with tachypnea, while the major physical signs are chest crackles and dullness.
      Surrogate biomarkers more easily obtainable in emergency facilities are C-reactive-protein
      (CRP), peripheral non-invasive pulse-oxymetry and neutrophil-to-lymphocyte ratio (NLR) which
      is an index of systemic inflammation associated also with pneumonia and subsequent outcome.

      The aim of this preliminary study is to evaluate if any clue and which biomarker, including
      NLR, assessed at Emergency Department (ED) triage, is predictive of the subsequent detection
      of lung consolidation by TUS and/or by CXR.

      The minimal groups' size, with and without TUS or CXR lung consolidation, was calculated
      according to the difference of the averages of neutrophil-to-lymphocyte ratio (NLR) in the
      reference the study of Yoon et al. Accepting alpha 0.01, for the probability of type 1 error,
      and power 80% for probability of type 2 error, a minimum sample size of 19 participants in
      each group (total 38) was required. Student's t-tests assessed the differences of CRP, WBC -
      white blood cells count - (TLC), neutrophil count (TNC) and NLR, between the groups with TUS
      and, separately, with CXR lung consolidation.Thereafter, by ROC (receiver operating curve)
      analysis, a cutoff of NLR, total leucocytes count (TLC), total Neutrophil count (TNC) and of
      CRP was calculated vs. the optimal reliability for the detection of TUS consolidation;
      sensitivity, specificity and accuracy (The proportion of all tests that are correct), and
      relative Odds Ratio (OR) and confidence intervals (CI) of the individual symptoms, and ORs of
      so defined laboratory assay cut-offs were calculated separately vs. TUS and CXR
      consolidation.
    

Intervention name(s): Thoracic Ultrasound (TUS)
Intervention type(s): Diagnostic Test
Observational model: Case-Only
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Criteria of exclusion: severe respiratory failure - pulse oxymetry ≥92%, myocardial
        infarction, acute pulmonary edema or severe heart failure, excluded on clinical basis,
        severe COPD excluded by patient's history and by subsequent CXR, CURB65 ≥3.