Abstract Pneumonia is a leading cause of severe morbidity and mortality among adults. During the last two decades, several scores were developed to evaluate the probability of morbidity and mortality among patients with community acquired pneumonia (CAP), such as the PORT score and the CURB65. Recently, several studies showed that elevated Red Cell Distribution Width (RDW) could be used as a prognostic tool for predicting severe morbidity and mortality among patients with cardiac diseases.

RDW is a quantitative measure for red blood cell (RBC) size variability. Recent studies have suggested that high levels of RDW are in association with higher mortality among cardiovascular patients.

RDW has not yet been studied as a prognostic sign in CAP. The goal of this study is to examine the role of RDW as a prognostic factor for severe morbidity and mortality among patients who were hospitalized with CAP , independently to Hemoglobin levels, renal function and inflammatory markers.

Inclusion Criteria:

patients 18 years and older, hospitalized due to pneumonia between 2005-2010. All patients must have RDW values.

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Exclusion Criteria:

• under 18 no RDW value The primary cause of hospitalization was not pneumonia

Adult patients with pneumonia