Use and outcomes of mechanical ventilation for people with severe mental disorders admitted due to natural causes: A nationwide population-based study.

Objective: To characterize temporal trends and outcomes of invasive mechanical ventilation (MV) for people with severe mental disorders (SMD) admitted due to natural causes.

Methods: We identified all 224,507 hospitalizations of patients aged 15-69 who underwent MV in Spain between 2000 and 2015, excluding poisonings and injuries, and divided them by presence of an SMD diagnosis. We compared the two study groups regarding demographic and clinical characteristics and examined time trends in the incidence of MV and in-hospital mortality.

Results: SMD patients were younger and had fewer comorbidities and lower in-hospital mortality than the non-SMD group. However, among patients admitted due to circulatory diseases, SMD patients had higher mortality risk (OR = 1.39; 95%CI = 1.22-1.59). In the SMD group, the increase in MV use quadrupled that of non-SMD patients (Average Annual Percent Change = 6.9%; 95%CI = 5.5-8.3 vs. 1.5%; 0.9-2.0, respectively). Overall in-hospital mortality declined similarly in both study groups. While the SMD group's circulatory-specific mortality also decreased, by 2015 it remained elevated in comparison to non-SMD patients (44% vs. 38%, respectively).

Conclusion: The increase in MV use due to natural causes among people with SMD outpaced that of non-SMD patients, with comparable decreasing trends in mortality. Although declining, SMD patients' higher circulatory-specific mortality risk requires further investigation.