The impact of patient ethnicity on haematopoietic cell transplantation outcome: a retrospective cohort study on the UK experience

Background: Patient ethnicity has been correlated with different outcomes after haematopoietic cell transplantation (HCT), with patients from minority ethnic backgrounds reported to have worse outcomes compared with White patients. To date, studies have been predominantly done in the USA, where health-care models are different to many European countries, including the UK. We aimed to evaluate the impact of patient-reported ethnicity on autologous and allogeneic HCT outcomes in the UK.

Methods: In this retrospective cohort study, patients who had autologous or allogeneic HCT between Jan 1, 2009, and Dec 31, 2019, and were registered in the British Society of Blood and Marrow Transplantation and Cellular Therapy patient registry were analysed as full cohorts and as separate adult (≥18 years) and paediatric (0–17·9 years) cohorts. Patient ethnicity was self-defined and grouped into four broad categories: Asian, Black, Other, and White. The outcome was 5-year overall survival, with overall survival defined as the time from transplantation to death from any cause.

Findings: 20 119 first autologous HCTs and 13 978 first allogeneic HCTs were analysed. Median times to follow-up were 60 months (IQR 35–89) for patients receiving autologous HCT and 32 months (10–68) for patients receiving allogeneic HCT. 5-year overall survival for the full allogeneic HCT cohort was 55% (95% CI 51–58). After adjustment for prognostic factors, Asian patients undergoing allogeneic HCT (n=1081) had significantly worse 5-year overall survival (hazard ratio [HR] 1·16 [95% CI 1·03–1·30], p=0·012) than White patients (n=11 705). Differences in overall survival between White (n=1489) and Asian patients (n=384) were most pronounced in paediatric patients (HR 1·67 [95% CI 1·28–2·19], p=0·00018). In the autologous HCT cohort, there were no associations between ethnicity and 5-year overall survival.

Interpretation: This large UK-based analysis suggests significant variation in outcomes after allogeneic HCT between patients of different ethnicities. The causes are unclear, and further research to elucidate and improve these health inequalities is warranted.

Funding: Anthony Nolan Charity and British Society of Blood and Marrow Transplantation and Cellular Therapy.