Predictive Factors for Invasive Mechanical Ventilation in Community-acquired Pneumonia

Objective Community-acquired pneumonia is an acute infectious disease with potentialy life-threatening consequences. Because invasive mechanical ventilation (IMV) requires the attention of many medical staff, early risk prediction at the time of admission is expected to lead to a predictable course of patient care and the appropriate allocation of medical resources. There are a limited number of reports on predictive factors for IMV, such as SMART-COP. Therefore, further studies are required. Methods We retrospectively reviewed cases of patients with community-acquired pneumonia other than coronavirus disease 2019 admitted to our institution from 2002 to 2019. We performed competing risks analysis with the need for IMV from the day after admission as the outcome and used multivariable analysis to identify predictive factors of IMV from admission characteristics. Results Among 2,227 patients (mean age 67.3 years, 69.0% male), 39 patients required IMV on or after the day following admission. A multivariable analysis showed that predictive factors of IMV were respiratory rate >30 breaths/min [subdistribution hazard ratio (SHR), 5.53; 95% confidence interval (CI), 2.09 to 14.67; p=0.001], PaO₂/FiO₂ ratio <250 (SHR, 8.02; 95% CI, 2.78 to 23.13; p<0.001), and Legionella pneumonia (SHR, 4.87; 95% CI, 1.56 to 15.13; p=0.006). Conclusion This study revealed that among other factors including mainly vital signs, specific infection by a microorganism itself (Legionella in this study) was a predictive factor for the need of IMV.