The Changing Comorbidity Burden and its Association with Outcomes in Acute NIV: A Charlson Comorbidity Index-Based Analysis.

Acute non-invasive ventilation (NIV) is a lifesaving treatment for acute hypercapnic respiratory failure, particularly during exacerbations of chronic obstructive pulmonary disease (COPD), and is also an established therapy that improves outcomes in acute cardiogenic pulmonary oedema. Decisions regarding NIV initiation are complex and require careful consideration of patient-specific factors. With an aging population, with increasing multimorbidity, understanding the evolving acute NIV patient characteristics is critical to optimize NIV delivery. We audited all adult acute NIV patients at a tertiary centre, pre-COVID (April 2019-March 2020) and post-COVID (April 2023-March 2024) and performed a retrospective observational cohort analysis. We compared the Charlson Comorbidity Index (CCI) scores and outcomes using Chi-squared or Mann-Whitney U. Three hundred and twelve patients received acute NIV, 171 pre-COVID and 141 post-COVID. Post-COVID patients had higher comorbidity burden vs pre-COVID (median CCI 5 vs 4, p=0.002), and ward-based NIV ceiling of care frequency (83% vs 66%, p=0.009). Across the entire cohort, higher CCI score associated with increased NIV failure (p=0.007) and in-hospital mortality (p<0.001). Our demonstration of increasing multimorbidity in a real-world cohort, and the association of multimorbidity with NIV failure, provides insights to guide optimization strategies for acute NIV services. Further understanding the evolving patient characteristics and their impact on outcome is essential to determine how best to incorporate comorbidity assessment into clinical decision making for improved NIV delivery.