Fig. 3

Forest plot of the adjusted SHR computed with multivariate computing risk regression of the probability of being successfully weaned from mechanical ventilation. eABT was defined as the first line of antibiotic therapy introduced during the first 24 h of ICU admission. COPD frequent exacerbator status was defined as at least two acute exacerbations of COPD with hospital admission within one year. Respiratory sample at AECOPD onset was defined as bacterial respiratory sample performed between 48 h before ICU admission and the end of ICU day-1. Univariate Fine and Gray analysis was first performed on each variable of interest (Additional file 1: Table S1). Then, the following variables were selected for inclusion in the multivariate model because of their assumed relevance: eABT status, centre, age, truncated SAPS2 (leaving out age, Glasgow Coma Scale, PaO2/FiO2 and temperature components to avoid collinearity with the other variables), home NIV or home oxygen status, COPD frequent exacerbator status, ICU day-1 cardiovascular and renal SOFA subscore (to avoid multicollinearity with SAPS2), ICU day-1 highest body temperature, ICU day-1 worst Glasgow, ICU day-1 worst PaCO2, ICU day-1 worst PaO2/FiO2 (PaO2/FiO2 was entered as a categorical variable because it was reported as a SAPS2 value when data were collected), invasive mechanical ventilation on ICU-day-1, respiratory sample at AECOPD onset, and cardiogenic pulmonary oedema on ICU day-1. Interactions were systematically checked for. We did not report any significant interaction between eABT and other variables included in our model. Then, we reduced our model by deleting all variables with multivariate p-value > 0.1. SHR lower than 1 indicates a lower probability of being successfully weaned from mechanical ventilation, accounting for the competing risk of death. SHR subdistribution hazard ratio; CI95% 95% confidence interval, NIV non-invasive ventilation, PaCO2 CO2 arterial partial pressure; PaO2/FiO2 ratio of O2 arterial partial pressure on fraction of inspired O2, SAPS2 simplified acute physiology score 2, SOFA Sequential Organ Failure Assessment, eABT early antibiotic therapy, COPD chronic obstructive pulmonary disease, ICU intensive care unit