“…All the included studies detected pretransplantation serum concentrations of sCD30 using an enzyme-linked immunosorbent assay technique except for one study using microsphere flow-cytometry assay. Among the 12 studies, 5 were performed in Europe (9,12,15,16,20), 3 in America (11,18,19), and 4 in Asia (10,13,14,17). All studies were retrospective cohort studies and did not adopt blind design.…”