Risk factors for bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation: a systematic review and meta-analysis.

BACKGROUND: Bronchiolitis obliterans syndrome (BOS) after hematopoietic stem cell transplantation (HSCT) is a late-onset complication that significantly impairs patients' quality of life and is associated with a high mortality rate. Currently, the risk factors for BOS after HSCT remain controversial. We therefore conducted a systematic review and meta-analysis to identify potential risk factors associated with BOS after HSCT. METHODS: Three primary medical databases (PubMed, Web of Science, Embase) were exhaustively reviewed from their inception through November 2024 to assess contributing factors for BOS occurrence following HSCT. Data synthesis was conducted using RevMan 5.4 for meta-analytic evaluation. RESULTS: Fourteen studies involving 10,317 HSCT recipients were included, 778 of whom developed BOS. Female sex (OR = 1.26; 95% CI: 1.08, 1.47; p = 0.003), ABO blood group incompatibility (OR = 1.39; 95% CI: 1.07, 1.81; p = 0.01), peripheral blood stem cell transplantation (PBSCT) (OR = 1.31; 95% CI: 1.04, 1.64; p = 0.02), myeloablative conditioning (MAC) (OR = 1.63; 95% CI: 1.23, 2.16; p = 0.0008), acute graft-versus-host disease (aGVHD) (OR = 1.93; 95% CI: 1.16, 3.23; p = 0.01), grade Ⅱ-Ⅳ aGVHD (OR = 1.41; 95% CI: 1.12, 1.77; p = 0.004), and extrapulmonary chronic graft-versus-host disease (cGVHD) (OR = 11.69; 95% CI: 5.29, 25.82; p < 0.00001) were associated with an increased risk of BOS after HSCT. CONCLUSIONS: Female sex, ABO blood group incompatibility, PBSCT, MAC, aGVHD (especially grade II-IV), and extrapulmonary cGVHD are associated with an increased risk of BOS after HSCT. PROSPERO REGISTRATION: CRD42024609569.