Peñuelas O, Muriel A, Abraira V, et al. - Since differences in clinical features and treatment and in the mortality of mechanically ventilated patients have not been adequately assessed, therefore, researchers analyzed four studies including 26,024 patients admitted to 1,253 units from 38 countries, to investigate if mortality shows a variability related to country following adjustment for clinical features and management. These studies were performed at 6-year intervals over an 18-year span. The outcome of interest was 28-day mortality. A significant reduction in adjusted 28-day mortality was seen over time (first study as reference). In patients with moderate hypoxemia and without hypoxemia, a moderate fraction of the impact of time on mortality was mediated by a protective ventilatory strategy and the use of continuous sedation, respectively. Mortality was significantly influenced by country, as revealed in logistic multilevel modeling. A possible contribution of country, independently of confounder variables, to the outcome, was suggested, and a reduction in the magnitude of the influence of country was seen over time.