A total of 2459 studies were retrieved of which 38 studies were included in a meta-analysis involving 22,304 patients. Risk factors identified were: older age, higher APACHE II scores, COPD, pneumonia, shock, low SaO2, low PaO2, low PaO2/FiO2, low hemoglobin, low albumin, high brain natriuretic peptide, low pH, high respiratory rate, low tidal volume, a higher rapid shallow breathing index, a lower vital capacity, a higher number of spontaneous breathing trials, prolonged length of mechanical ventilation, weak cough, a reduced patient's cough peak flow and positive cuff leak test. Subgroup analysis showed that risk factors substantially overlap when reintubation was considered within 48 hours or within 72 hours after extubation.