Table 1. Independent variables used in this study.

Variable	Question	Category
Sociodemographic factors
Gender	What is your gender?	Male or female
Age group	What is your age?	19–44, 45–64, 64–74, or ≥75 years
Residence type	Where is your residence?	Urban or rural
Marital status	Have you ever been married (including a de facto marriage)? Which of the following is your current marital status? (1) I have a spouse and we live together (2) I have a spouse but we do not live together (3) No spouse due to death (4) No spouse due to divorce	Never married, married, divorced/separated, or widowed
Household composition	Which of the following is your household type?	Living alone, single generation, two generations, or three generations
Education level	Where did you go to school? Did you graduate from school?	No formal education, primary school, middle or high school, or college and higher
Monthly household income	What was your average monthly household income in the past year, including wages, real estate income, pensions, interest, government subsidies, and allowances for relatives or children?	≤1, 1.01–2, 2.01–4, or ≥4.01 million won
Employment status	What is your occupation? Please list the specific type of work.	Employed, unemployed, or housewife/student
National Basic Livelihood Security status	Does your household currently receive National Basic Livelihood Security?	Recipient or non-recipient
Socio-familial relationships
Contact with family	How often do you see or contact your closest relatives (including your family)?	<1 time or ≥1 time per month
Contact with neighbors	How often do you see or contact your closest neighbors?	<1 time or ≥1 time per month
Contact with friends	How often do you see or communicate with your closest friends (except your neighbors)?	<1 time or ≥1 time per month
Religious activities	Do you participate in religious activities once per month or more?	<1 time or ≥1 time per month
Activities with friends	Do you regularly participate in activities with friends once per month or more?	<1 time or ≥1 time per month
Leisure activities	Do you participate regularly in leisure activities at least once per month?	<1 time or ≥1 time per month
Charitable activities	Do you participate in charitable activities once per month or more?	<1 time or ≥1 time per month
Health behaviors and health status
Smoking status	Have you smoked more than 5 packs (100 cigarettes) during your life? Do you smoke now? (1) I smoke every day (2) Sometimes I smoke (3) I smoked in the past but I do not smoke now	Never, former, or current smoker
Frequency of alcohol use	Have you ever drunk more than one drink in your life? Have you been drinking for the last year? How often do you drink alcohol?	None, ≤1, 2–3, or ≥4 times per week
Walking activity	How many days did you walk for at least 10 minutes at a time in the last week?	≤2 or ≥3 times per week
Sleep duration	How many hours a day do you usually sleep?	≤6, 7–8, or ≥9 h per day
Self-rated health	What do you think about your health?	Good, fair, or poor
Perceived daily stress	How often do you feel stressed in your daily life?	Low or high
Experience of depressed mood	Have you ever felt sad or desperate for more than two consecutive months during the past year to the extent that it interferes with your daily life?	No or yes
Number of chronic diseases	Have you been diagnosed with any of the following diseases: obesity, hypertension, diabetes, dyslipidemia, stroke, myocardial infarction, angina pectoris, osteoarthritis, osteoporosis, asthma, or hepatitis B?	≤2 and ≥3
Diagnosis of depression	Have you been diagnosed with depression?	No or yes
Suicide attempts	Have you attempted suicide in the last year?	No or yes