Incidence and Risk Factors for Invasive Mechanical Ventilation Dependency in Japan: A Nationwide Retrospective Cohort Study

Objectives To describe the incidence and risk factors for becoming dependent on invasive mechanical ventilation (IMV) in Japan. Design Retrospective cohort study using a nationwide inpatient database from April 1, 2014, to March 31, 2020. Setting More than 1500 acute care hospitals participating in the Diagnosis Procedure Combination Study Group Database, covering approximately 50% of all hospitalizations in acute care hospitals in Japan. Patients Adults (≥18 years), in whom IMV was initiated during hospitalization. IMV-dependency was defined as discharge while still receiving IMV after ≥7 days and having undergone tracheostomy during hospitalization. Interventions None. Measurements And Main Results Of the 388,752 patients in whom IMV was initiated, 7805 (2.0%) became IMV dependent. In-hospital mortality occurred in 138,111 (35.5%) patients, and 242,836 (62.5%) were discharged without IMV dependency. The incidence of IMV dependency increased over time, from 1.6% in 2014 to 2.4% in 2019. Patients who became IMV dependent had a mean age of 71.3 years, and 49% were ≥75 years. Emergency admissions accounted for 91.7% of cases, and 68.1% presented with impaired consciousness at admission. In multinomial regression analysis (reference: discharged alive without IMV dependency), older age (≥75 years; RRR 1.48, 95% CI 1.41-1.56), impaired consciousness at admission (RRR 1.75, 95% CI 1.63-1.88), emergency admission (RRR 2.18, 95% CI 1.97-2.42), and surgery prior to IMV (RRR 1.92, 95% CI 1.82-2.03) were independently associated with IMV dependency. Conclusions The incidence of IMV dependency increased over time. Identified risk factors may inform clinical decision-making and advance care planning.