For clinical parameters, 7 out of 13 articles showed that positive PD-L1 expression was more common with international prognostic index (IPI) scores of 3–5 in DLBCL patients (OR = 1.552, 95% CI: 1.111–2.169, P = 0.010; I2 = 12.40%, P = 0.335) [11, 17, 18, 21, 22, 26, 27]. This evidence concerns the gene CD274 and diffuse large B-cell lymphoma.