Risk of ankylosing spondylitis in long-term follow-up of hematopoietic stem cell donors: impact of HLA-B27 status and donation type.

Hematopoietic stem cell transplantation (HSCT) is a pivotal curative therapy for various hematologic diseases, and donor safety is paramount. A few cases of ankylosing spondylitis (AS) have been reported in healthy unrelated donors, but the incidence has not been previously described. This retrospective cohort study analyzed 1098 bone marrow (BM) and 3890 peripheral blood stem cell (PBSC) donors between January 1998 and December 2018, along with healthy participants from the donor registry using de-identified data from the Taiwan National Health Insurance Research Database. The overall AS incidences among donors and non-donors were both 0.38%. AS incidence did not differ between BM and PBSC donors and their matched counterparts. Individuals with HLA-B27 exhibited higher incidence rate ratios than those without HLA-B27 in both the BM and PBSC cohorts. In those individuals with HLA-B27, BM donors showed a relative risk of 3.85 (p = 0.0017) compared to non-donors, while the risk for PBSC donors was not significantly higher (1.36, p = 0.339). The findings suggest that while AS incidence among HSC donors is comparable to non-donors, HLA-B27 positivity is the main risk factor associated with AS development, particularly among BM donors. This study provides valuable insights into the safety of HSCT donation and long-term follow-up.