Validation of a Community-Acquired Pneumonia Score To Improve Empiric Antibiotic Selection at an Academic Medical Center

The 2019 American Thoracic Society and the Infectious Diseases Society of America community-acquired pneumonia (CAP) guidelines recommend that drug-resistant pathogens (DRP) be empirically covered if locally validated risk factors are present. This retrospective case-control validation study evaluated the performance of the drug resistance in pneumonia (DRIP) clinical prediction score. Two hundred seventeen adult patients with ICD-10 (https://www.who.int/classifications/classification-of-diseases) pneumonia diagnosis, positive confirmed microbiologic data, and clinical signs and symptoms were included. A DRIP score of ≥4 was used to assess model performance. Logistic regression was used to select for significant predictors and create a modified DRIP score, which was evaluated to define clinical application. The DRIP score predicted pneumonia due to a DRP with a sensitivity of 67% and specificity of 73%. The area under the receiver operating characteristic (AUROC) curve was 0.76 (95% confidence interval [CI], 0.69 to 0.82). From regression analysis, prior infection with a DRP and antibiotics in the last 60 days, yielding scores of 2 points and 1 point, respectively, remained local risk factors in predicting drug-resistant pneumonia. Sensitivity (47%) and specificity (94%) were maximized at a threshold of ≥2 in the modified DRIP model. Therefore, prior infection with a DRP remained the only clinically relevant predictor for drug-resistant pneumonia. The original DRIP score demonstrated a decreased performance in our patient population and behaved similarly to other clinical prediction models. Empiric CAP therapy without anti-methicillin-resistant Staphylococcus aureus and antipseudomonal coverage should be considered for noncritically ill patients without a drug resistant pathogen infection in the past year. Our data support the necessity of local validation to authenticate clinical risk predictors for drug-resistant pneumonia.