Predicting nosocomial pneumonia risk in level-1 trauma patients: An external validation study using the trauma quality improvement program

Background: Early identification of patients at risk of nosocomial pneumonia enables the opportunity for preventative measures, which may improve survival and reduce costs. Therefore, this study aimed to externally validate an existing prediction model (issued by Croce et al.) to predict nosocomial pneumonia in patients admitted to US level-1 trauma centers. Methods: A retrospective cohort study including patients admitted to level-1 trauma centers and registered in the TQIP, a US nationwide trauma registry, admitted between 2013–2015 and 2017–2019. The main outcome was total nosocomial pneumonia for the first period and ventilator-associated pneumonia (VAP) for the second. Model discrimination and calibration were assessed before and after recalibration. Results: The study comprised 902,231 trauma patients (N_2013–2015 ​= ​180,601; N_2017–2019 ​= ​721,630), with a median age of 52 in both periods, 64–65 ​% male, and approximately 90 ​% sustaining blunt traumatic injury. The median Injury Severity Scores were 13 (2013–2015) versus 9 (2017–2019); median Glasgow Coma Scale scores were 15. Nosocomial pneumonia incidence was 4.4 ​%, VAP incidence was 0.7 ​%. The original model demonstrated good to excellent discrimination for both periods (c-statistic_2013–2015 0.84, 95%CI 0.83–0.84; c-statistic_2017–2019 0.92, 95%CI 0.91–0.92). After recalibration, discriminatory capacity and calibration for the lower predicted probabilities improved. Conclusions: The Croce model can identify patients admitted to US level-1 trauma centers at risk of total nosocomial pneumonia and VAP. Implementing (modified) Croce models in route trauma clinical practice could guide judicious use of preventative measures and prescription of additional non-invasive preventative measures (e.g., increased monitoring, pulmonary physiotherapy) to decrease the occurrence of nosocomial pneumonia in at-risk patients.