Table 3 Multivariate Cox regression analysis for the impact of disaster on cognitive decline among participants who are aged over 85

1.13

0.97–1.31

1.23

1.04–1.45

0.85

0.60–1.20

Age (ref = 85–89)

90–94

1.08

1.04–1.12

1.10

1.05–1.15

1.02

0.96–1.09

over 95

1.18

1.12–1.23

1.27

1.19–1.36

1.04

0.96–1.12

0.95

0.91–0.98

0.94

0.89–0.98

0.99

0.92–1.06

Level of dementia symptomatology assessment before disaster (ref = II b)

Independent

1.65

1.56–1.75

1.62

1.52–1.73

2.21

1.94–2.51

I

1.27

1.21–1.33

1.24

1.17–1.31

1.49

1.35–1.64

II a

1.36

1.29–1.42

1.39

1.30–1.48

1.31

1.20–1.43

III a

0.61

0.58–0.65

0.72

0.67–0.78

0.53

0.49–0.58

III b

0.52

0.48–0.57

0.62

0.55–0.71

0.47

0.42–0.52

IV

0.10

0.09–0.12

0.15

0.12–0.19

0.08

0.07–0.10

1.28

1.18–1.39

1.33

1.21–1.46

1.11

0.95–1.30

0.98

0.97–0.99

0.98

0.97–0.99

0.99

0.97–1.01

1.36

1.31–1.41