PD-1/PD-L1 + CTLA-4), the impact of PD-1/PD-L1 on the risk of pneumonitis was weaker than that of the control group (OR = 0.43, 95%CI [0.25, 0.74], I2 = 25%, Z = 3.09 (P = 0.002); Fig. 2D) [23, 74, 81, 82, 86]. Here, PDCD1 is linked to pneumonitis.