Bone Marrow Quality Index: A Predictor of Acute Graft-versus-Host Disease in Hematopoietic Stem Cell Transplantation for Thalassemia

Abstract

Bone marrow (BM) continues to be the preferred source of stem cells in allogenic transplantation for nonmalignant disorders. Granulocyte colony-stimulating factor (G-CSF)-primed BM is associated with low rates of acute graft-versus-host disease (aGVHD) and allows reduced collection volumes while ensuring speedy engraftment. However, variability in BM harvest quality is a concern. This study evaluated the utility of a novel indicator, the Bone Marrow Quality Index (BMQI), to predict aGVHD. We analyzed 184 consecutive first matched related donor bone marrow transplants for thalassemia using G-CSF-primed bone marrow over 6 years from March 2017 to April 2023 across 2 centers in India. BMQI was defined as the ratio of the G-CSF-primed BM WBC count to the peripheral blood WBC count within 24 hours of harvest. European Society for Blood and Marrow Transplantation criteria were used to grade aGVHD. The log-rank test was used to assess the impact of BMQI on aGVHD. The chi-square test was used to compare categorical data, and the Wilcoxon rank-sum test was used to compare the numerical data. A Cox proportional hazards model was used to investigate the association of BMQI vis-à-vis other factors on aGVHD. Of the 184 patients studied, 19 had a BMQI <.9, 18 had a BMQI between .9 and 1, and the remaining 147 had a BMQI >1. The rate of aGVHD grade II-IV was 37% in patients with a BMQI <.9 , 22% in those with BMQI .9 to 1, and 12% in those with BMQI >1 (P = .018). Patients with BMQI <.9 had a 3.1-fold greater chance (95% confidence interval [CI], .9 to 10.6) and those with BMQI .9 to 1 had a 2-fold greater chance (95% CI, .5 to 6.6) of developing aGVHD grade II-IV. BMQI was the significant predictor associated with aGVHD hazard (P = .014). BMQI appears to be the most relevant and controllable predictor of aGVHD. It is a novel, informative, and very simple indicator that could influence aGVHD prophylaxis decision making. Our indicator is accurately measurable, inexpensive, precise, and timely; furthermore, it does not involve any sophisticated equipment and thus may be widely applicable. Prior knowledge of poor BM quality may help intensify prophylaxis and monitoring for aGVHD, as well as trigger a review of collection procedures.

Keywords: Bone marrow transplantation; Graft vs host disease; Granulocyte colony-stimulating factor; Quality indicators.