Table 2.

Association between dementia and ADL 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)	7.29 (6.15–8.64)	< 0.001	7.20 (6.07–8.53)	< 0.001	7.19 (6.05–8.53)	< 0.001	4.59 (3.30–6.39)	< 0.001
Age	1.13 (1.09–1.16)	< 0.001	1.13 (1.10–1.16)	< 0.001	1.13 (1.10–1.17)	< 0.001	1.13 (1.10–1.17)	< 0.001
Gender (ref = male) Female	1.55 (1.25–1.91)	< 0.001	1.53 (1.23–1.89)	< 0.001	1.44 (1.16–1.78)	0.001	1.44 (1.16–1.78)	< 0.001
Study year (ref = 2001)
2010	0.78 (0.63–0.97)	0.025	0.86 (0.69–1.07)	0.182	0.83 (0.66–1.04)	0.107	0.58 (0.41–0.83)	0.002
2018	0.66 (0.54–0.81)	< 0.001	0.74 (0.60–0.92)	0.007	0.69 (0.56–0.86)	0.001	0.47 (0.34–0.66)	< 0.001
Occupational class (ref = Non-manual)
Manual			0.97 (0.81–1.16)	0.741	0.94 (0.79–1.13)	0.505	0.93 (0.78–1.12)	0.463
Housewives			0.92 (0.66–1.28)	0.630	0.93 (0.66–1.29)	0.649	0.92 (0.66–1.29)	0.642
Unknown			2.28 (1.67–3.13)	< 0.001	2.28 (1.66–3.14)	< 0.001	2.30 (1.68–3.14)	< 0.000
Number of morbidities 0 (ref)
1					0.94 (0.70–1.28)	0.698	0.95 (0.70–1.29)	0.739
2					0.90 (0.67–1.21)	0.496	0.93 (0.69–1.24)	0.611
3					1.26 (0.93–1.71)	0.135	1.29 (0.95–1.75)	0.103
≥ 4					1.85 (1.33–2.56)	< 0.001	1.88 (1.36–2.61)	< 0.001
Dementia * study year (ref = 2001)
Dementia * 2010							1.80 (1.15–2.83)	0.010
Dementia * 2018							1.85 (1.21–2.83)	0.005

ADL disability = dependent in at least one activity among dress and undress and get in and out of bed. Outcome variable is ADL 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