Table 1.

Quality assessment of the included studies examining the relationship between altitude and the prevalence of hypertension

Study ID	Study design	Definition of hypertension	Definition of awareness	Definition of treatment	Definition of control	Sampling strategy	Response rate	Adequate sample size	Validated measure	Appropriate statistical analysis
Sherpa33	Cross-sectional	≥130/85 mm Hg or antihypertensive therapy	Self-report of prior diagnosis by a healthcare professional	Self-reported use of a prescribed medication	Medication treatment with BP <140/90 mm Hg	Stratified	82%	Yes	Yes	Yes
Zhao34	Cross-sectional	≥140/90 mm Hg or antihypertensive therapy	Self-report of prior diagnosis by a healthcare professional	Self-reported use of a prescribed medication	Medication treatment with BP <140/90 mm Hg	Stratified	100%	Yes	Yes	Yes
Zheng35	Cross-sectional	≥140/90 mm Hg or antihypertensive therapy	Self-report of prior diagnosis by a healthcare professional	Self-reported use of a prescribed medication during last 2 weeks	Medication treatment with BP <140/90 mm Hg	Stratified	96.8%	Yes	Yes	Yes
Deji36	Cross-sectional	≥140/90 mm Hg or antihypertensive therapy	Self-report prior to the survey	Self-reported use of a prescribed medication during last 2 weeks	Medication treatment with BP <140/90 mm Hg	Randomised	65%	Yes	Yes	Yes
Lei37	Cross-sectional	≥140/90 mm Hg	Self-report prior to the survey	Self-reported use of a prescribed medication during last 2 weeks	Medication treatment with BP <140/90 mm Hg	Not reported	100%	Yes	Yes	Yes
Zhang38	Cross-sectional	≥140/90 mm Hg or proof of hospital diagnosis	Not reported	Not reported	Not reported	Randomised	89%	Yes	Yes	Yes
Liu11	Cross-sectional	≥140/90 mm Hg or antihypertensive therapy	Not reported	Not reported	Not reported	Randomised	100%	Yes	Yes	Yes
Li39	Cross-sectional	≥140/90 mm Hg	Not reported	Not reported	Not reported	Random, cluster and multistage	87%	Yes	Yes	Yes