Table 4 Multiple linear regression exploring the relationship between BMI and EQ-5D index scores

Age (years)

 65–69

1

1

 70–74

-0.010

< 0.0001

-0.021

< 0.0001

 75–79

-0.027

< 0.0001

-0.056

< 0.0001

 ≥ 80

-0.075

< 0.0001

-0.106

< 0.0001

Marital status

 Currently married

1

1

 Never married,

 Separated,

 Divorced,

 Widowed

-0.012

< 0.0001

-0.007

0.0001

Annual household income (USD)

 > 15,664

1

1

 4,700 to < 15,664

-0.020

< 0.0001

-0.011

< 0.0001

 < 4,700

-0.040

< 0.0001

-0.035

< 0.0001

Education

≥ College graduate

1

1

 High school,

 Junior high

 school graduate

-0.012

< 0.0001

-0.018

< 0.0001

 ≤ Elementary

 school graduate

-0.034

< 0.0001

-0.053

< 0.0001

Residence area

 Rural

1

1

 Urban (dong)

-0.007

< 0.0001

-0.011

< 0.0001

Smoking status

 Current smoker

1

1

 Past smoker

-0.005

0.0115

0.005

0.5455

 Never smoker

0.005

0.0412

0.033

< 0.0001

Drinking status

 High-risk drinking

1

1

 Moderate drinking

-0.002

0.4748

-0.028

0.0380

 Non-drinking

-0.038

< 0.0001

-0.054

< 0.0001

Breakfast

 0–4/week

1

1

 5–7/week

0.026

< 0.0001

0.035

< 0.0001

Regular walking

 ≥ 5 day/week (30 min/day)

1

1

 < 5 day/week (30 min/day)

-0.044

< 0.0001

-0.056

< 0.0001

Body mass index

 18.5–22.9 (Normal)

1

1

 < 18.5 (Underweight)

-0.044

< 0.0001

-0.031

< 0.0001

 23.0–24.9 (Pre-obesity)

0.013

< 0.0001

0.001

0.6025

 ≥ 25.0 (Obesity)

0.006

0.0022

-0.017

< 0.0001

Diabetes or Hypertension

 Yes (≥ 1)

1

1

 No

0.020

< 0.0001

0.020

< 0.0001