Background The very old patients (≥ 80 years-old, VOP) comprise a subpopulation increasingly admitted to intensive care units (ICUs). Community-acquired pneumonia (CAP) is a common reason for admission and the best strategy of mechanical ventilation for respiratory failure in this scenario is not fully known.
Methods Multicenter cohort study of VOPs admitted with CAP in need of invasive (IMV) or noninvasive (NIV) mechanical ventilation to 11 Brazilian ICUs from 2009 through 2012. We used logistic regression models to evaluate the association between ventilator strategy (NIV vs. IMV) and hospital mortality adjusting for confounding factors. We evaluated effect modification with interaction terms in pre-specified sub-groups.
Results Of 369 VOPs admitted for CAP with respiratory failure, 232 (63%) received NIV and 137 (37%) received IMV as initial ventilatory strategy. IMV patients were sicker at ICU admission (median SOFA 8 vs. 4, p < 0.001). Hospital mortality was 114/232 (49%) for NIV and 90/137 (66%) for IMV. For the comparison NIV vs. IMV (reference), the crude odds ratio (OR) was 0.50 (95% CI, 0.33–0.78, p=0.002). This association was largely confounded by antecedent characteristics and non-respiratory SOFA (adjOR = 0.70, 95% CI, 0.41–1.20, p=0.196). The fully adjusted model, including Pao2/Fio2 ratio, pH and Paco2, yielded an adjOR of 0.81 (95% CI, 0.46–1.41, p=0.452). There was no strong evidence of effect modification among relevant subgroups, such as Pao2/Fio2 ratio ≤ 150 (p = 0.30), acute respiratory acidosis (p = 0.42) and non-respiratory SOFA ≥ 4 (p = 0.53).
Conclusions NIV was not associated with lower hospital mortality when compared to IMV in critically ill VOP admitted with CAP, but there was no strong signal of harm from its use. The main confounders of this association were both the severity of respiratory dysfunction and of extra-respiratory organ failures.