July Effect on Mortality and Complications in Patients With ARDS in US Teaching Hospitals.

BACKGROUND Each July, teaching hospitals in the United States experience an influx of new resident and fellow physicians. It has been theorized that this occurrence may be associated with increased patient mortality, complication rates, and health care resource use, a phenomenon known as the "July effect." OBJECTIVE To assess the existence of a July effect in clinical outcomes of patients with acute respiratory distress syndrome (ARDS) receiving mechanical ventilation in the intensive care unit in US teaching hospitals. METHODS The National Inpatient Sample database was queried for all adult patients with ARDS who received mechanical ventilation from 2012 to 2014. Using a multivariate difference-in-differences (DID) model, differences in mortality, ventilator-associated pneumonia, iatrogenic pneumothorax, central catheter-associated bloodstream infection, and Clostridium difficile infection were compared between teaching and nonteaching hospitals during April-May and July-August. RESULTS There were 70 535 and 43 175 hospitalizations meeting study criteria in teaching and nonteaching hospitals, respectively. Multivariate analyses revealed no differential effect on the rates of all-cause inpatient mortality (DID, 0.66; 95% CI, -0.42 to 1.75), C difficile infection (DID, 0.29; 95% CI, -0.19 to 0.78), central catheter-associated bloodstream infection (DID, 0.14; 95% CI, -0.04 to 0.33), iatrogenic pneumothorax (DID, 0.00; 95% CI, -0.25 to 0.24), ventilator-associated pneumonia (DID, 0.22; 95% CI, -0.05 to 0.49), and any complication (DID, 0.60; 95% CI, -0.01 to 1.20) for July-August versus April-May in teaching hospitals compared with nonteaching hospitals. CONCLUSION This study did not show a differential July effect on mortality outcomes and complication rates in ARDS patients receiving mechanical ventilation in teaching hospitals compared with nonteaching hospitals.