Table 1 Description of variables

SHI

The respondent was insured by any of the social health insurance (SHI) schemes; Yes = 1; No^a = 0

Age (Years)

Age of the respondent

Gender

Gender of the respondent; Female^a = 0; Male = 1

Education level

Highest education level achieved of the respondent; Illiterate^a = 0; Primary school = 1; Middle school = 2; High school and above = 3

Marital status

Marital status of the respondent; With a spouse = 1; Without a spouse^a (including unmarried, divorced, or widowed) = 0

Living with children

The respondent lived with children; Yes = 1; No^a = 0

Job

Job status of the respondent; Without a job (including get retired)^a = 0; Agricultural job = 1; Non-agricultural job = 2

Income (RMB)

The annual per capita household income

Ln income

The natural logarithm of the sum of the annual per capita household income and 1

Childhood health

Score of self-rated childhood health status of the respondent (range: 1–5); Much healthier = 1; Somewhat healthier = 2; Average = 3; Somewhat less healthy = 4; Much less healthy = 5

SRH

Score of self-rated health (SRH) status of the respondent (range: 1–5); Very good = 1; Good = 2; Fair = 3; Poor = 4; Very Poor = 5

Chronic diseases

The respondent ever suffered from chronic diseases; Yes = 1; No^a = 0

ADL disability

The respondent had disability with activities of daily life (ADL); Yes = 1; No^a = 0

PHI

The respondent was insured by supplementary private health insurance (PHI); Yes = 1; No^a = 0

Travel time (Minutes)

Travel time to the nearest healthcare institution by conventional transportation

Urban or rural

Urban or rural area according to National Statistical Bureau; Urban = 1; Rural^a = 0

City GRP (RMB)

Gross Regional Product (GRP) per capita of the sample city in the previous year

ln city GRP

The natural logarithm of GRP per capita of the sample city in the previous year

Region

Region of the sample community; East China^a = 0; Central China = 1; West China = 2