Table 2.

Subgroup analyses of the prognostic effect on OS of the sarcopenia vs. non-sarcopenia group in head and neck cancer.

Variable	Subgroups	Availability		Effect		Heterogeneity
		Studies (N)	Patients (N)	HR (95% CI)	P-values	I2 (%)	$p_{inter}^{\ast }$
Race	Asian Non-Asian	4 6	678 1,793	2.11 [1.59, 2.81] 1.92 [1.64, 2.25]	<0.00001 <0.0001	39 0	0.5
Stage	Locally advanced	4	837	1.92 [1.35, 2.73]	0.0003	49	0.95
	Non-metastasis	5	1,520	2.04 [1.71, 2.42]	<0.0001	0
	Contained M1	1	114	1.94 [1.04, 3.55]	0.04	–
Primary SMI	L3	6	1,128	2.12 [1.66, 2.71]	<0.00001	7	0.47
	C3	4	1,343	1.90 [1.60, 2.25]	<0.00001	0
†Cutoff	Group1	3	708	2.41 [1.72, 3.38]	<0.0001	0	0.45
	Group2	3	1,056	1.87 [1.47, 2.38]	<0.00001	14
	Group3	4	707	1.92 [1.53, 2.41]	<0.00001	0
NOS quality	NOS ≥ 7 NOS = 6	6 4	1,410 1,061	2.13 [1.74, 2.60] 1.83 [1.48, 2.26]	<0.0001 <0.00001	0 8	0.3
HR data extract	Directly Indirectly	8 2	2,138 333	2.11 [1.81, 2.47] 1.50 [1.11, 2.03]	<0.00001 0.008	0 0	0.05

^*P_inter represents the significance of heterogeneity between subgroups calculated by Revman software.

^†Cutoff value in Group 1: 38.5 cm²/m² for women and 52.4 cm²/m² for men; Group 2: 30.3–31 cm²/m² for women and 42.4–49 cm²/m² for men; Group 3: 41–43.2 cm²/m² for women and 41–43.2 cm²/m² for men.

N, number; HR, hazards ratio; NOS, Newcastle–Ottawa Scale.