Table 2. Subgroup analysis of the impact of country, sex ratio, and sample size on the pooled findings.

Terms	Subgroups	Number	Ratio, (%)	95%CI	I2, (%)	P
CVD	Country
	China	17	0.02	0.01-0.03	77	<0.00001
	British	1	0.12	0.06-0.18	—	0.0002
	Sex ratio (Males/Females)
	<1	4	0.02	0.01-0.04	0	0.002
	≥1	14	0.03	0.02-0.04	84	<0.00001
	Sample size
	<100	8	0.02	0.01-0.03	0	0.003
	>100	10	0.03	0.02-0.05	89	<0.0001
HTN	Country
	China	37	0.19	0.15-0.23	96	<0.00001
	Other countries	4	0.51	0.48-0.54	67	<0.00001
	Sex ratio (Males/Females)
	<1	11	0.18	0.10-0.25	94	<0.00001
	≥1	30	0.25	0.17-0.32	99	<0.00001
	Sample size
	<100	22	0.20	0.15-0.25	81	<0.00001
	>100	19	0.26	0.16-0.36	99	<0.00001
D or H	Country
	China	36	0.14	0.08-0.20	99	<0.00001
	Other countries	—	—	—	—	—
	Sex ratio (Males/Females)
	<1	11	0.08	0.06-0.10	45	<0.00001
	≥1	25	0.16	0.08-0.24	99	0.0001
	Sample size
	<100	21	0.16	0.01-0.31	99	0.04
	>100	15	0.11	0.09-0.14	89	<0.00001

(CVD: cerebrovascular disease; HTN: hypertension; D or H: dizziness or headache).