Table 3 Association between dementia and mobility disability among the oldest old in 2001, 2010, and 2018

Dementia (ref = no dementia)

3.35 (2.90–3.86)

< 0.001

3.28 (2.84–3.78)

< 0.001

3.34 (2.89–3.87)

< 0.001

2.42 (1.79–3.28)

< 0.001

Age

1.17 (1.14–1.20)

< 0.001

1.17 (1.14–1.20)

< 0.001

1.17 (1.14–1.21)

< 0.001

1.17 (1.14–1.21)

< 0.001

Gender (ref = male) Female

2.44 (2.07–2.88)

< 0.001

2.45 (2.07–2.89)

< 0.001

2.21 (1.87–2.62)

< 0.001

2.21 (1.87–2.62)

< 0.001

Study year (ref = 2001)

 2010

1.10 (0.91–1.33)

0.314

1.15 (0.95–1.40)

0.155

1.06 (0.87–1.29)

0.582

0.90 (0.71–1.15)

0.404

 2018

0.82 (0.69–0.98)

0.030

0.87 (0.72–1.04)

0.129

0.75 (0.62–0.90)

0.002

0.64 (0.51–0.81)

< 0.001

Occupational class (ref = Non-manual)

 Manual

1.33 (1.15–1.54)

< 0.001

1.25 (1.08–1.46)

0.003

1.25 (1.08–1.46)

0.004

 Housewives

1.04 (0.79–1.37)

0.793

1.02 (0.77–1.35)

0.913

1.01 (0.76–1.35)

0.920

 Unknown

1.48 (1.09–2.01)

0.012

1.48 (1.09–2.02)

0.013

1.50 (1.10–2.05)

0.010

Number of morbidities 0 (ref)

 1

1.35 (1.05–1.75)

0.021

1.36 (1.05–1.76)

0.019

 2

1.80 (1.40–2.31)

< 0.001

1.83 (1.43–2.35)

< 0.001

 3

2.54 (1.95–3.31)

< 0.001

2.58 (1.98–3.36)

< 0.001

 ≥ 4

4.89 (3.58–6.67)

< 0.001

4.96 (3.63–6.77)

< 0.001

Dementia * study year (ref = 2001)

 Dementia * 2010

1.56 (1.04–2.33)

0.033

 Dementia * 2018

1.50 (1.04–2.17)

0.032