Table 1 Independent variables and their coding

Gender

Male =0, Female =1

Poverty

Poor [annual per capita income below CNY 2300 (or USD 362.82) or lived in poor households] =1, Not-poor =0

Level of education

Low (junior high school and below) =1, Middle (high school and technical school) =2, High (senior for college, college, undergraduate and higher education) =3

Occupation

Unemployed =1, Retired =2, Employed =3

Ethnicity

Hui =1, Mongolian =2, Other minority (Zhuang, Manchu, Bai, etc.) =3, Han =4

Marital status

Single =1, Widowed/Divorced =2, Married =3

Smoking

Non-smoker (never having smoked previously) =1, Former smoker (previously smoked but quit) =2, Current smoker (currently consumed cigarettes) =3

Drinking

Yes = Drinker (consumed alcohol within the previous 12 months at the time of the interview) =1, No = Non-drinker (no consumed alcohol within this time period) =0

BMI (kg/m²)

BMI < 24 = 0, BMI ≥24 = 1

Comorbidity

No =0,Yes =1