Characteristics and outcomes of Bahraini pediatric patients sent abroad for bone marrow transplantation: A ten-year retrospective cohort study

Abstract

Background: Bone marrow transplantation (BMT) is a breakthrough procedure for patients with hematological and oncological conditions, particularly when all other treatments fail. Its indications vary between patients and settings, and its outcomes depend on the donor type, transplantation facility, and center expertise. In countries where transplantation facilities are lacking, sending patients abroad for transplantation might be a safe and effective alternative to leaving the patient to face eventual disease morbidity or even mortality if the procedure is not performed locally. However, studies evaluating BMT abroad are scarce.

Aim: To assess the clinical characteristics of patients who underwent BMT overseas and analyze the factors affecting their survival outcomes.

Methods: We conducted a retrospective cohort study of all Bahraini pediatric patients who underwent BMT between 2013 and 2024. Medical records from Salmaniya Medical Complex and Overseas Treatment Office were reviewed. Patient demographics, transplant indications, donor type, transplantation type, overseas centers, complications, and outcomes (overall and 5-year survival rates) were analyzed. Clinical characteristics and outcomes were compared using χ ² test, Student's t-test, Mann-Whitney U test, and Kaplan-Meier method. Univariate and multivariate analyses were used to estimate survival predictors.

Results: Of the 75 listed patients, 62 (82.7%) underwent BMT and were included, 10 (13.3%) did not, and 3 (4.0%) were awaiting transplantation. Most patients were male (n = 33, 53.2%). The mean age at transplantation was 7.8 ± 4.9 years. The main indication for treatment was acute myeloid leukemia (AML) (n = 15, 36.6%). Six patients (9.7%) required re-transplantation. Of the 68 transplants, 60 (88.2%) involved conditioning, mostly a combination of fludarabine and total body irradiation (n = 7, 11.7%). Most patients underwent allogeneic transplantation (n = 48, 77.4%), primarily from related donors (n = 47/48, 97.9%). The most common complication was infection (n = 51, 79.7%). Follow-up averaged 3.3 ± 2.5 years. The overall survival rate was 77.4%. Survival odds were better for non-AML patients and Middle Eastern centers (P = 0.015 and P = 0.032, respectively).

Conclusion: Bahraini males with AML primarily underwent allogeneic BMT. Non-AML patients and those transplanted in the Middle East had better survival rates, despite high complication rates.

Keywords: Acute myeloid leukemia; Allogeneic; Autologous; Bahrain; Bone marrow transplantation; Complications; Mortality; Pediatrics; Survival.

Figure 1

Flow charts of pediatric patients who underwent an overseas bone marrow transplantation, Kingdom of Bahrain, 2013-2024. BMT: Bone marrow transplantation.

Figure 2

Donor-recipient relationship of patients who underwent bone marrow transplantation (n = 67/68, 98.5%). BMT: Bone marrow transplantation.

Figure 3

The main countries where the Kingdom of Bahrain sent pediatric patients overseas to undergo bone marrow transplantation. Middle East countries included Jordan (n = 41, 66.2%), Turkey (n = 7, 11.3%), and Saudi Arabia (n = 4, 6.5%); Asia and Pacific countries included Singapore (n = 7, 11.3%); European countries included Germany (n = 2, 3.2%) and United Kingdom (n = 1, 1.6%). ^aPearson’s χ² test.

Figure 4

Conditioning regimens of patients who underwent bone marrow transplantation (n = 60/68 bone marrow transplantations). Other conditioning regimens are shown in Supplementary Table 2. BMT: Bone marrow transplantation; Bu: Busulfan; Mel: Melphalan; Cy: Cyclophosphamide; Etop: Etoposide; CB: Carboplatin; Flu: Fludarabine; TT: Thiotepa; ATG: Antithymocyte globulin; TBI: Total body irradiation.

Figure 5

Survival analysis based on type of transplant in pediatric patients post bone marrow transplantation using the Kaplan-Meier method.