Table 1. Sampling schemes for the CHSIS survey [A] and sampling levels for the analysis of Uncontrolled Hypertension [B]. [A] Sampling design for the CHSIS survey. [B] Sampling levels in the analysis of Uncontrolled Hypertension. The sampling scheme for the current study of Uncontrolled Hypertension [B] is derived from the survey design for the BPHS survey [A].

Sampling levels		BPHS program
		Combined		Predominantly urban		Predominantly rural
1. Regions a		3		---		---
2. Provinces with BPHS programs		17		---		---
3. Municipalities with BPHS programs		17		---		---
4. Districts or counties b		34 b		17 districts		17 counties
5. Streets or townships
Total		102		52		50
per districts or county		3		~3b		~3b
6. Neighborhood committees or villages
Total		408		209		199
Estimates per street or township		4		~4		~4
7. Households
Total		20,777		10,665		10,112
Mean ± sd [per neighborhood or village		50.9±4.4		51.0±4.1		50.8±4.8
Range [per neighborhood or village]		20–70		38–70		20–70
8. Survey respondents
Total		62,097		30,320		31,777
Mean ± sd [per household]		3.0±1.3		2.8±1.2		3.1±1.4
Range [per household]		1–12		1–9		1–12
Sampling levels		Uncontrolled hypertension among BPHS respondents
		Combined		Urban		Rural
1. Regions		3		---		---
2. Provinces		17		---		---
3. Municipalities		17		---		---
4. Districts or counties		34		17 districts		17 counties
5. Streets or townships
Total		102		52		50
Mean ± sd [per districts or county]		3.0 ± 0		1.97 ± 0.80		1.87 ± 0.51
Range [per districts or county]		3–3		1–3		1–3
6. Neighborhood committees or villages
Total		408		209		199
Mean ± sd [per street or township]		4.0 ± 0.2		4.0 ± 0.2		4.0 ± 0.1
Range [per street or township]		3–5		3–5		3–4
7. Households
Total		7,867		4,300		3,567
Mean ± sd [per neighborhood or village]		22.7 ± 7.8		23.9 ± 7.9		21.2 ± 7.5
Range [per neighborhood or village]		2–42		3–41		2–42
8. Survey respondents
Total		9,607		5,338		4,269
Mean ± sd [per household]		1.22 ± 0.44		1.24 ± 0.45		1.20 ± 0.41
Range [per household]		1–4		1–4		1–3
9 Analytical cohort [1 respondent per household]
Total		7,867		4,300		3,567
Mean [per household]		1		1		1
Range		1–1		1–1		1–1

^a Broad regions of China: Eastern, Central and Western China [18].

^b In a small number of municipalities, the areas surveyed were exclusively urban (2 districts) or exclusively rural (2 districts).

^c The selection of neighborhood committees and villages followed the principle of 4 per street or township strictly. Therefore, in theory there would be 208 neighborhood committee and 200 villages; and therefore, the mean± sd and range are not applicable (N/A) here. However, when implementing the survey one village was replaced by a neighborhood committee within an urban district, because rural villages were much less in number than urban neighborhood committees, which resulted in 209 neighborhood committees and 199 villages.