Modified IDSA/ATS minor criteria for severe community-acquired pneumonia best predicted mortality

Background: It is not clear whether the 2007 IDSA/ATS minor criteria for severe community-acquired pneumonia (CAP) could further be simplified and even be modified to orchestrate an improvement in predicting mortality Methods: A retrospective cohort study of 1230 CAP patients was performed to simplify and to modify the scoring system by excluding four noncontributory or infrequent variables (leukopenia, hypothermia, hypotension and thrombocytopenia) and by excluding these variables and then adding age ≥ 65 yrs, respectively. The simplification and modification were tested against a prospective two centre validation cohort of 1409 adults with CAP. Results: The mortalities were 1.3% and 3.8% in the retrospective and prospective cohorts, respectively. The increasing numbers of the minor criteria present were positively associated with the mortalities in the two cohorts, showing significant increased odds ratios for mortality. The sensitivity, specificity, positive predictive value, and Youden9s index of the modified minor criteria for mortality prediction were the best pattern in the retrospective cohort. High values of corresponding indices were confirmed in the validation cohort. The highest accuracy of the modified version for predicting mortality in the retrospective cohort was illustrated by the highest area under the receiver operating characteristic curve of 0.925. The validation cohort confirmed a similar paradigm. Conclusions: The IDSA/ATS minor criteria could be simplified to five variables to orchestrate an improvement in predicting mortality in CAP patients and then to facilitate their use. The modified version best predicted mortality.