Abstract Carbon monoxide (CO)‐based tests have precisely measured hemolysis for over 40 years. End‐tidal CO was the primary marker in clinical hematology research, followed by carboxyhemoglobin. Quantification of CO reflects heme oxygenases degrading heme in a 1:1 stoichiometric ratio, making CO a direct marker of hemolysis. CO in alveolar air can be quantified using gas chromatography, whose high resolution allows detecting mild and moderate levels of hemolysis. CO can be elevated in active bleeding, resorbing hematoma, and smoking. Clinical acumen and other markers remain necessary to diagnose the cause of hemolysis. CO‐based tests constitute an opportunity for bench‐to‐bedside technology transfer.
We studied the outcome of 213 patients who received allo-HSCT for hematological malignancies, 121 (57%) from HLA identical siblings, 63 (29%) from 10/10 HLA identical unrelated donors and 29 (14%) from 9/10 HLA mismatched unrelated donors. Engraftment was lower in the 9/10 HLA group (90%) than in the 10/10 HLA group (95%) than in the sibling group (99%); 3 months CI of aGVHD ≥ 2 was 32% (23-41), 20% (15-26) and 27% (23-32) respectively; the one year CI of extensive cGVHD was 21% (13-30), 9% (5-13) and 17% (14-21) respectively. The median OS was 10 months (5-21), 18 months (11-NR) and 60 months (31-NR) respectively with 2-years probability of 19% (8-44), 43% (31-59) and 63% (54-74) respectively. TRM was significantly higher in the 9/10 HLA group with 1 year CI of 45% (35-55), compared to 33% (27-39) in the unrelated 10/10 HLA group and 12% (9-15) in the identical siblings group (p < 0.001).
