Table 1.

Definition/codes of the control variables

	Variables	Codes/definition
Predisposing Characteristics	Gender	0 = Male; 1 = Female
	Age	Continuous variable
	Marital statues	0 = Single; 1 = Partnered
	Education	1 = Illiterate; 2 = Primary school and lower; 3 = Junior middle school; 4 = Senior middle school and higher
Enabling Resources	Medical insurance	0 = None; 1 = Yes
	Pension	Whether received any pension or not: 0 = No; 1 = Yes
	Financial support from children	Financial support received from children: 0 = None; 1 = 0-2000yuan; 2 = 2000-5000yuan; 3 = 5000-10000yuan; 4 = 10000yuan or more
	Smoke	0 = No; 1 = Yes
	Drink	0 = No; 1 = Yes
Need	Chronic diseases	0 = None; 1 = Yes
	Number of ADL limitations	Range from 0 to 6
	Number of IADL limitations	Range from 0 to 6
	Self-rated health	1 = very good; 2 = good; 3 = fair; 4 = poor; 5 = very poor
	Year	2015; 2018

Note: ADL activities of daily living; IADL instrument activities of daily living