1038. Can Serum Procalcitonin (PCT) Help Interpret Inconclusive Chest Radiographs (CXR) in Patients with Acute Respiratory Illness (ARI)?
Session: Poster Abstract Session: Diagnostic Procedures in Clinical Practice
Saturday, October 22, 2011
Room: Poster Hall B1

Background: Diagnosis of pneumonia in busy emergency rooms is often based on inconclusive CXR readings (edema vs. atelectasis vs. infiltrate) driving unnecessary antibiotic use to meet CMS guidelines. Recently, serum procalcitonin (PCT) has been used to guide antibiotic use in ARI, presumably by identifying bacterial infection (PCT ≥ 0.5 ng/ml). Thus, we correlated serum PCT with CXR findings, specifically to aid in evaluation of inconclusive CXR findings.


Methods: Patients hospitalized for ARI during the winters 2008 and 2009 were recruited. Evaluation included review of CXR reports, measurement of PCT on admission, and viral and bacterial diagnostics. A pulmonologist evaluated all patients and independently read all CXRs. For both the radiologist (RAD) and pulmonologist (PULM), CXRs were classified as (1) no acute disease (NAD), (2) other [i.e., atelectasis, mass, effusion, etc.], (3) possible infiltrate [inconclusive], or (4) infiltrate.


Results: 532 patients with 556 illnesses were recruited, of which 18 were excluded (No CXR or non-pulmonary infection) leaving 538 illnesses for evaluation. CXR reads by RAD were inconclusive in 31% of cases. Readings by PULM were; 31% infiltrates, 54% NAD, 14% other, and 0.9% inconclusive. Mean admission PCT levels were significantly higher in subjects with infiltrates vs. NAD classified by PULM (0.31±1.83 ng/ml vs. 4.84 ± 26.47 ng/ml, p=.004). PCT was >0.5ng/ml in 6% of patients with NAD and 42% of those with infiltrates. All patients with bacteremia had PCT > 0.5ng/ml. Of the 167 inconclusive RAD CXRs, those with PCT ≥ 0.5ng were more likely to have bacterial infections and infiltrates as read by PULM vs. those < 0.5ng/ml. (Table)





PULM Infiltrates

PCT ≥ 0.5ng/ml


6 (14%)

19 (43%)

36 (77%)

PCT < 0.5ng/ml


44 (36%)

14 (11%)

50 (41%)


Conclusion: Measurement of serum PCT levels in patients with ARI and inconclusive CXR may be useful in making antibiotic decisions.  In stable patients with low PCT and inconclusive CXR findings, appropriate microbiologic specimens should be sought prior to hastily initiating antibiotics.

Subject Category: J. Clinical practice issues

Edward Walsh, MD1,2, Andrew Swinburne, MD2, Eric Nylen, MD3, Richard Snider, PhD3, Kenneth Becker, MD, PHD3 and Ann Falsey, MD1, (1)University of Rochester School of Medicine, Rochester, NY, (2)Rochester General Hospital, Rochester, NY, (3)VAMC, George Washington University, Washington, DC


E. Walsh, None

A. Swinburne, None

E. Nylen, None

R. Snider, None

K. Becker, None

A. Falsey, Sanofipasteur: Consultant, Consulting fee and Research support
GLaxosmithKline: Consultant, Consulting fee and Research support
Medimmune: Consultant, Consulting fee
AstraZeneca: Consultant, Consulting fee
Novartis: Consultant, Consulting fee

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.