Table 2.

Subgroup analyses for short-term mortality.

Factors	Subgroup	RR and 95% CI	P-value	Heterogeneity (%)	P-value for heterogeneity	P-value between subgroups
Country	US	0.70 (0.47–1.04)	.080	26.4	.246	.044
	Other	0.93 (0.80–1.09)	.373	25.9	.213
Sample size	≥100	0.89 (0.78–1.02)	.087	15.1	.304	.802
	<100	0.63 (0.23–1.70)	.358	68.8	.022
Mean age, y	≥60.0	0.84 (0.69–1.03)	.090	54.3	.032	.548
	<60.0	0.94 (0.63–1.40)	.752	0.0	.436
Percentage of male patients (%)	≥70.0	0.91 (0.61–1.36)	.638	0.0	.454	.782
	<70.0	0.85 (0.69–1.05)	.140	54.2	.026
Tracheotomy methods	Open	0.94 (0.60–1.45)	.770	0.0	.484	.309
	Percutaneous	0.78 (0.60–1.01)	.061	51.3	.055
	Both	0.97 (0.83–1.14)	.752	0.0	.396
Study quality	High	0.92 (0.76–1.11)	.397	27.0	.204	.195
	Low	0.82 (0.58–1.15)	.246	47.7	.105