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Table 2 Cumulative incidence and odds ratios (ORs) for cognitive declinea according to levels of predictor variables

From: Short daytime napping reduces the risk of cognitive decline in community-dwelling older adults: a 5-year longitudinal study

Predictors

Cumulative incidence

Unadjusted OR (95% CI)

Adjusted ORb (95% CI)

Fully-adjustedc OR (95% CI)

Age (years)

 

P for trend< 0.0001

  

 65–69

12/97 (12.4%)

1 (Ref)

  

 70–79

46/200 (23.0%)

2.12 (1.06–4.21)

  

 80–89

45/87 (51.7%)

7.59 (3.63–15.85)

  

 90–99

3/5 (60.0%)

10.62 (1.61–70.22)

  

Sex

 Men

46/159 (28.9%)

1 (Ref)

1 (Ref)

 

 Women

60/230 (26.1%)

0.87 (0.55–1.36)

0.80 (0.49–1.29)

 

Area of residence

 Heisei-cho

30/103 (29.1%)

1 (Ref)

1 (Ref)

 

 Matto

37/165 (22.4%)

0.70 (0.40–1.23)

0.70 (0.39–1.27)

 

 Katakai

39/121 (32.2%)

1.16 (0.65–2.05)

1.14 (0.62–2.09)

 

Family environment

 Living with family

94/359 (26.2%)

1 (Ref)

1 (Ref)

 

 Living alone

12/30 (40.0%)

1.88 (0.87–4.05)

1.81 (0.81–4.03)

 

Job status

 Employed

23/136 (16.9%)

1 (Ref)

1 (Ref)

 

 Unemployed/retired

83/253 (32.8%)

2.40 (1.43–4.03)

1.78 (1.03–3.07)

 

History of hypertension

 Absent

44/198 (22.2%)

1 (Ref)

1 (Ref)

 

 Present

62/191 (32.5%)

1.68 (1.07–2.64)

1.23 (0.76–1.99)

 

History of cerebrovascular disease

 Absent

101/374 (27.0%)

1 (Ref)

1 (Ref)

 

 Present

5/15 (33.3%)

1.35 (0.45–4.05)

1.23 (0.40–3.80)

 

History of diabetes

 Absent

99/356 (27.8%)

1 (Ref)

1 (Ref)

 

 Present

7/33 (21.2%)

0.70 (0.29–1.66)

0.72 (0.29–1.77)

 

Alcohol consumptiond(gou/wk)

 

P for trend = 0.3590

P for trend = 0.7898

 

 Non-drinker

64/208 (30.8%)

1 (Ref)

1 (Ref)

 

  < 7

13/58 (22.4%)

0.65 (0.33–1.29)

0.71 (0.34–1.45)

 

 7–13

11/58 (19.0%)

0.53 (0.26–1.08)

0.70 (0.33–1.48)

 

 14–20

11/44 (25.0%)

0.75 (0.36–1.58)

0.95 (0.43–2.09)

 

  ≥ 21

7/21 (33.3%)

1.13 (0.43–2.92)

1.88 (0.68–5.18)

 

Smoking

 

P for trend = 0.2706

P for trend = 0.0563

 

 Non-smoker

72/277 (26.0%)

1 (Ref)

1 (Ref)

 

 Past smoker

17/62 (27.4%)

1.08 (0.58–2.00)

1.31 (0.67–2.56)

 

 Current smoker

17/50 (34.0%)

1.47 (0.77–2.79)

1.94 (0.97–3.87)

 

Bedtime

 

P for trend = 0.0698

P for trend = 0.1472

P for trend = 0.0480

 -8:59 p.m.

13/45 (28.9%)

1 (Ref)

1 (Ref)

1 (Ref)

 9:00–9:59 p.m.

38/116 (32.8%)

1.20 (0.57–2.54)

1.28 (0.58–2.85)

1.29 (0.55–3.04)

 10:00–10:59 p.m.

33/118 (28.0%)

0.96 (0.45–2.04)

0.93 (0.42–2.09)

0.80 (0.32–2.00)

 11:00 p.m.-

22/110 (20.0%)

0.62 (0.28–1.36)

0.71 (0.30–1.65)

0.50 (0.18–1.39)

Duration of nighttime sleep (hr)

 

P for trend = 0.0284

P for trend = 0.2737

P for trend = 0.7540

  < 6

17/71 (23.9%)

1.00 (0.50–1.97)

1.16 (0.57–2.36)

1.33 (0.61–2.88)

 6–6.9

24/103 (23.3%)

0.96 (0.52–1.78)

1.03 (0.54–1.94)

1.13 (0.57–2.24)

 7–7.9

30/125 (24.0%)

1 (Ref)

1 (Ref)

1 (Ref)

 8–8.9

26/67 (38.8%)

2.01 (1.06–3.81)

1.67 (0.84–3.32)

1.55 (0.74–3.26)

  ≥ 9

9/23 (39.1%)

2.04 (0.80–5.17)

1.73 (0.63–4.76)

1.47 (0.50–4.35)

Duration of daytime nap (min)

 

P for trend = 0.1085

P for trend = 0.8387

P for trend = 0.9923

 None

44/153 (28.8%)

1 (Ref)

1 (Ref)

1 (Ref)

 1–29

15/98 (15.3%)

0.45 (0.23–0.86)

0.46 (0.23–0.90)

0.47 (0.23–0.96)

 30–59

21/74 (28.4%)

0.98 (0.53–1.82)

0.83 (0.43–1.59)

0.79 (0.40–1.58)

  ≥ 60

26/64 (40.6%)

1.70 (0.92–3.12)

1.11 (0.57–2.15)

1.05 (0.51–2.13)

Sleep disturbance

 Absent

91/338 (26.9%)

1 (Ref)

1 (Ref)

 

 Present

14/50 (28.0%)

1.06 (0.54–2.05)

1.20 (0.60–2.41)

 

Use of sleeping pills

 No

81/308 (26.3%)

1 (Ref)

1 (Ref)

 

 Yes

25/81 (30.9%)

1.25 (0.73–2.14)

1.13 (0.64–2.00)

 
  1. aΔHDS-R ≤ 3
  2. bAdjusted for age and baseline HDS-R score
  3. cAdjusted for age, baseline HDS-R score, sex, region (dummy variables), family environment, job status, histories of hypertension, cerebrovascular diseases, and diabetes, alcohol consumption, smoking status, bedtime, duration of sleep, duration of nap (0, 1–29 min; 1, others), presence of sleep disturbance, and use of sleeping pills
  4. dEquivalent to Japanese sake (1 gou of sake is equivalent to 180 ml sake or 27 g ethanol)
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BMC Geriatrics

ISSN: 1471-2318

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