Burden of Morbidity after Allogeneic Blood or Marrow Transplantation for Inborn Errors of Metabolism – A BMTSS Report

• Approximately one-half of survivors of inborn errors of metabolism develop severe chronic health conditions after bone marrow transplantation. • Reduced-intensity conditioning is associated with a greater hazard of chronic health conditions • Young adult survivors face significant challenges with societal reintegration. Survival after blood or marrow transplantation (BMT) for inborn errors of metabolism (IEM) is excellent; however, the burden of morbidity in long-term survivors of BMT for IEM remains understudied. This study examined the risk of chronic health conditions (CHC) in ≥2-year survivors of allogeneic BMT for IEM performed between 1974 and 2014 using the BMT Survivor Study. In this retrospective cohort study, participants (or their parents; n = 154) reported demographic data and CHCs (graded using Common Terminology Criteria for Adverse Events version 5), and transplantation characteristics were obtained from institutional databases. Unaffected siblings (n = 494) served as a comparison group. Logistic regression was used to estimated the odds of severe/life-threatening CHCs compared with siblings. Cox proportional hazards regression was used to estimate factors associated with severe/life-threatening/fatal CHCs in survivors of BMT for IEM. Survivors of allogeneic BMT for IEM (leukodystrophies, 43.5%; mucopolysaccharidoses, 41.0%) were at 12.5-fold higher odds of severe/life-threatening CHCs (95% confidence interval [CI], 5.4 to 28.9) compared with their siblings. The mean 10-year post-BMT cumulative incidence of grade 3-5 CHCs was 47.5 ± 4.0%. Reduced-intensity conditioning (RIC) was associated with a 2.7-fold higher risk (95% CI, 1.2 to 6.2; P = .02) of any grade 3-5 CHC, a 6.7-fold higher risk of grade 3-5 cardiopulmonary conditions (95% CI, 1.3 to 35.4), and a 3.0-fold higher risk of severe hearing/vision deficits (95% CI, 1.4 to 6.6). Older (age >26 years) BMT survivors were significantly less likely to graduate from college (odds ratio [OR], 0.3; 95% CI, 0.1 to 0.7) or marry (OR, 0.01; 95% CI, 0.004 to 0.07) compared with their siblings. Survivors of BMT for IEM carry a significant burden of morbidities, which affects their ability to attain adult milestones. Efforts to reduce chronic health conditions in this population are needed.