Background: The Clinical Pulmonary Infection Score (CPIS) has been used in the intensive
care unit (ICU) as a decision tool for initiation of antibiotics in suspected pneumonia and also
for discontinuing antibiotics if the CPIS score is ≤6 on day three of therapy, but it is not in
common clinical use. We sought to determine if application of a CPIS score ≤6 at three days
could reduce antibiotic use and if a blinded committee would have a greater percentage of
patients with CPIS >6 on day one receiving antibiotics empirically for pneumonia.
Methods: Over 11 months, we evaluated empiric antibiotics prospectively in two ICUs of a
large tertiary university teaching hospital. A pneumonia committee (PC) reviewed all patients
and defined pneumonia according to the guidelines of the U.S. Centers for Disease Control
and Prevention (CDC). The CPIS was calculated for all patients at day one and day three of
antibiotic therapy. The percentage of patients with a CPIS ≤6 was compared for the ICU and
PC, and the total antibiotic days potentially saved by using CPIS ≤6 as the criterion for treatment
were determined. Receiver operating characteristic (ROC) curves and inter-observer reliability
were determined.
Results: Three hundred twelve patients received empiric antibiotics, 83 of whom were believed
to have pneumonia by the ICU staff (2,283 antibiotic days). On day one, the 55 patients
started on antibiotics had a CPIS ≤6, with 1,460 antibiotic-days, and only 28 patients had a
CPIS >6 (823 antibiotic-days). In contrast, the PC determined 19 patients (23%) to have pneumonia
by the CDC definition (731 antibiotic-days), with eight of these patients having a CPIS
≤6 and 11 a CPIS >6. Pneumonia committee review resulted in fewer patients believed to
have pneumonia and a greater percentage with a CPIS >6 (odds ratio [OR] 2.7; 95% confidence
interval [CI] 0.86, 8.6; p = 0.05). Restriction of antibiotics to patients with a CPIS >6
would have saved 1,460 antibiotic-days at day one and 1,053 days if treatment was delayed
until day three. Clinical Pulmonary Infection Score ROC curves for the PC showed an area
under the curve (AUC) of 0.82 (95% CI 0.72, 0.91), whereas the AUC for the ICU group was
0.85 (95% CI 0.79, 0.92). The sensitivity and specificity of a CPIS >6 for the PC were 79% and
75%, respectively, with correct prediction 76% of the time. The inter-observer reliability of
the CPIS had a kappa value of 0.88.
Conclusions: This prospective evaluation confirms that 50% of antibiotic-days in our ICU
are used empirically for pneumonia when that infection is not likely to be present by either
CDC or CPIS criteria. Although the CPIS has good reliability and acceptable sensitivity and
specificity, PC review and CPIS ≤6 were commonly divergent (42–47%). Thus, better strategies
should be developed for identification of pneumonia and empiric antibiotic administration
in the ICU.
