Table 3.

Subgroup analyses for ventilator-associated pneumonia.

Factors	Subgroup	RR and 95% CI	P-value	Heterogeneity (%)	P-value for heterogeneity	P-value between subgroups
Country	US	0.94 (0.77–1.15)	.526	79.7	<.001	.535
	Other	0.86 (0.69–1.07)	.185	53.2	.046
Sample size	≥100	0.82 (0.68–0.98)	.033	56.9	.017	<.001
	<100	1.05 (0.97–1.15)	.229	0.0	.895
Mean age, y	≥60.0	0.83 (0.60–1.15)	.257	67.4	.009	.237
	<60.0	0.94 (0.79–1.11)	.463	74.5	.001
Percentage of male patients (%)	≥70.0	0.95 (0.77–1.16)	.598	72.5	.026	.005
	<70.0	0.78 (0.58–1.05)	.102	66.8	.006
Tracheotomy methods	Open	1.05 (0.97–1.15)	.220	0.0	.922	<.001
	Percutaneous	0.74 (0.52–1.06)	.103	71.5	.004
	Both	0.86 (0.60–1.23)	.401	–	–
Study quality	High	0.93 (0.78–1.11)	.432	69.5	.003	.061
	Low	0.85 (0.64–1.13)	.262	65.8	.012