Table 3 Variables assignment

Self-rated health status

 < 85 = 0, ≥ 85 = 1

Age

 ≤ 65 = 0, 65–80 = 1, > 80 = 2

Residence

Rural = 0, Urban = 1,

Education level

Illiteracy = 1, Primary school = 2, Junior high school = 3, High school/Technical school = 4, College degree and above = 5

Pre-retirement occupation^a

Government staffs = 1, Industry and service workers = 2, Agricultural staffs and others = 3

Medical insurance

Basic Medical Insurance for Urban Employees = 1, Basic Medical Insurance for Urban and Rural Residents = 2, Others = 3

Communication methods^b

Smartphone = 1, Non-smartphone = 2, Landline = 3, Others = 4