Fig. 1

Flowchart for data sources of the study participants. The 2009 CHNS survey, the 2011 CHARLS survey, and the 2001–2018 NHANES surveys were employed to explore cross-sectional relationships. To examine longitudinal associations, the 2009 CHNS and the 2011 CHARLS surveys served as baseline data, and the 2011, 2015 CHNS surveys alongside the 2013, 2015 CHARLS surveys provided the follow-up data