The prognostic significance of PD-L1 and PD-1 expression in patients with nasopharyngeal carcinoma: a systematic review and meta-analysis

Table 3 Subgroup analysis of included studies about PD-L1 and OS in this meta-analysis

Subgroup	No. of studies	No. of patients	HR (95% CI)	p value	Heterogeneity		Statistical model used
Subgroup	No. of studies	No. of patients	HR (95% CI)	p value	I² (%)	p value	Statistical model used
Cut-off value for PD-L1 positive
≥ 5%	5	606	0.98 (0.70, 1.35)	0.89	0	0.77	Fixed
≥ 1%	2	217	0.83 (0.50, 1.37)	0.47	0	0.59	Fixed
Detection area
Tumor cells	10	1561	1.55 (0.99, 2.42)	0.06	79	0.000	Random
Immune cells	3	483	0.68 (0.47, 0.99)	0.04	0	0.57	Fixed
TC or IC	2	275	0.82 (0.51, 1.31)	0.40	0	1.00	Fixed
Calculation of HRs
Multivariate	9	1558	1.40 (0.93, 2.10)	0.11	81	0.000	Random
Univariate	9	1146	1.06 (0.58, 1.91)	0.86	79	0.000	Random
Estimation method of HRs
Reported	10	1604	1.37 (0.92, 2.03)	0.12	79	0.000	Random
K–M curve	3	342	3.12 (0.49, 19.83)	0.23	88	0.000	Random

HRs: hazard ratios; IC: immune cells; K–M curve: Kaplan–Meier curve; No: number; OS: overall survival; TC: tumor cells; 0.000, P < 0.001

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