Higher vs. lower haemoglobin threshold for transfusion in septic shock: subgroup analyses of the TRISS trial

Background: Using a restrictive transfusion strategy appears to be safe in sepsis, but there may be subgroups of patients who benefit from transfusion at a higher haemoglobin level. We explored if subgroups of patients with septic shock and anaemia had better outcome when transfused at a higher vs. a lower haemoglobin threshold. Methods: In post-hoc analyses of the full trial population of 998 patients from the Transfusion Requirements in Septic Shock (TRISS) trial, we investigated the intervention effect on 90-day mortality in patients with severe comorbidity (chronic lung disease, haematological malignancy or metastatic cancer), in patients who had undergone surgery (elective or acute) and in patients with septic shock as defined by the new consensus definition: lactate above 2 mmol/l and the need for vasopressors to maintain a mean arterial pressure above 65 mmHg. Results: The baseline characteristics were mostly similar between the two intervention groups in the different subgroups. There were no differences in the intervention effect on 90-day mortality in patients with chronic lung disease (test of interaction P = 0.31), haematological malignancy (P = 0.47), metastatic cancer (P = 0.51), in those who had undergone surgery (P = 0.99) or in patients with septic shock by the new definition (P = 0.20). Conclusion: In exploratory analyses of a randomized trial in patients with septic shock and anaemia, we observed no survival benefit in any subgroups of transfusion at a haemoglobin threshold of 90 g/l vs. 70 g/l.