Permanent Impairment-Free, Relapse-Free Survival: A Novel Composite Endpoint to Evaluate Long-Term Success in Allogeneic Transplantation

Permanent impairment (PI) of vital organs is one of the transplantation-related health problems affecting the quality of life and morbidity even in patients who do not develop graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HCT), but no data are available on PI of multiple organs. This retrospective study aimed to estimate a novel composite endpoint of PI-free, relapse-free survival (PIRFS) in 164 allo-HCT recipients. We defined PI as >26% to 30% impairment of the whole person in 6 vital organs using the whole person impairment rating. Conventional GVHD-free/relapse-free survival (GRFS) and PIRFS at 5 years were 33.8% (95% confidence interval [CI], 26.5% to 41.3%) and 40.6% (95% CI, 32.6% to 48.4%), respectively. In the whole cohort, PIRFS was higher than GRFS at any time after allo-HCT. However, PIRFS was lower than GRFS after day 397 post-transplantation in patients who underwent umbilical cord blood transplantation (UCBT). In UCBT recipients, 5-year GRFS and PIRFS were 47.6% (95% CI, 34.3% to 59.7%) and 39.2% (95% CI, 26.6% to 51.5%), respectively. The cumulative incidence of PI after 5 years was 20.9% (95% CI, 13.7% to 29.0%) in patients surviving for ≥6 months without relapse. The multivariate analysis revealed that high disease risk (hazard ratio [HR], 1.91; 95% CI, 1.26 to 2.88; P < .01) and Karnofsky Performance Status score ≤90% at transplantation (HR, 1.73; 95% CI, 1.14 to 2.63; P = .01) were correlated with the lower PIRFS, whereas UCBT (HR, 2.35; 95% CI, 1.11 to 4.99; P = .03), grade III-IV acute GVHD by day 180 (HR, 3.59; 95% CI, 1.04 to 12.4; P = .04), and thrombotic microangiopathy by day 180 (HR, 2.74; 95% CI, 1.10 to 6.87; P = .03) were significantly correlated with a higher incidence of PI. More than 20% of long-term survivors had PI. Our data suggest that PIRFS is a useful endpoint for assessing long-term transplantation success from a different perspective than has been established previously.