Comorbid conditions after allogeneic haematopoietic stem cell transplantation in young adults in Germany-A prospective, multicentre trial.

Young adults (YA) are particularly affected by comorbid conditions following allogeneic haematopoietic stem cell transplantation (alloHSCT), as they have to live with them for many years. This is the first multicentre prospective study investigating sequelae after alloHSCT in YA in Germany. In total, 107 patients who survived relapse-free until day 100 after alloHSCT were enrolled. Median patient age was 29.3 years. Chronic graft-versus-host disease (cGvHD) occurred in 40.2%. Comorbidities were captured at days 100, 180, 365 and 910 by applying the post-transplant multimorbidity index (PTMI). Considering all time points, 12.5%-23.5% of patients had no comorbidity, while 39.2%-49.5% had 1-3, 26.3%-33.0% had 4-6 and 5.7%-8.4% had >6 PTMI-defined comorbidities respectively. The most prevalent PTMI-based comorbidities were iron overload, hypogonadism, arterial hypertension, infections, hepatic dysfunction and osteopenia/osteoporosis. However, the spectrum of PTMI-recorded comorbidities and those concurrently self-reported by patients differed substantially. Factors linked to a higher PTMI were total body irradiation and active cGvHD. Investigating single PTMI-defined comorbidities, we found significant associations of osteopenia/osteoporosis with cGvHD, ongoing immunosuppression and hypogonadism, which was more common among female survivors. These results provide a detailed analysis of the occurrence of a vast spectrum of PTMI-defined comorbidities in YA after alloHSCT.