Table 4 Variables assignment

SPAOA^a

 < 90 points = 0, ≥ 90 points = 1

Age

60 ≤ Age < 70 = 1, 70 ≤ Age < 80 = 2, Age >  = 80 = 3

Sex

Male = 0, Female = 1

Residence

Urban = 0, Rural = 1

Educational level

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

Pre-retirement occupation^b

Government staffs = 1, Industry and service workers = 2, Agricultural staffs = 3, Others = 4

Income

1000and below = 1, 1001–2000 = 2, 2001–3000 = 3, 3001and above = 4

Medical insurance^c

Basic Medical Insurance for Urban Employees = 1, Basic Medical Insurance for Urban Residents = 2, New Rural Cooperative Medical System = 3, Others = 4