Table 2. Characteristics of the included studies.

MetS: metabolic syndrome.

Author	Year	Study design	Region	Subjects	Study about the risk or survival outcome
Duggan et al. [13]	2011	Prospective cohort	United States (New Mexico, Seattle, Los Angeles)	527	Survival outcome
Sieri et al. [14]	2012	Prospective cohort	Italy (Lombardy)	10,786	Risk
Zhang et al. [15]	2012	Retrospective cohort	China (Jiaxing city)	7,950	Risk
Jiralerspong et al. [16]	2013	Prospective cohort	United States (Texas)	6,342	Survival outcome
Nam et al. [6]	2016	Prospective cohort	Korea (Seoul)	1,301	Survival outcome
Kabat et al. [17]	2017	Prospective cohort	United States (40 clinical sites across the nation)	21,000	Risk
Shu et al. [18]	2018	Case-control	European descent	Cases: 98,842; controls: 83,464	Risk
Buono et al. [11]	2020	Prospective cohort	Italy (Pascale, Naples)	MetS = 173; non-MetS = 544	Survival outcome