Table 3.

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

Variables	Model 1		Model 2		Model 3		Model 4
	OR (95% CI)	p	OR (95% CI)	p	OR (95% CI)	p	OR (95% CI)	p
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

Mobility disability = dependent in at least one activity among moving indoors, walking 400 m, and climbing stairs. Outcome variable is mobility disability in all models

The explanatory variables are as follows

Model 1 – dementia, age, gender, and study year

Model 2 – dementia, age and gender, study year, and occupational class

Model 3 – dementia, age, gender, study year, occupational class, and multimorbidity

Model 4 – dementia, age, gender, study year, occupational class, multimorbidity, and interaction between dementia and study year