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Table 2 The results of subgroup analysis

From: The preventive efficacy of vitamin B supplements on the cognitive decline of elderly adults: a systematic review and meta-analysis

Outcome measures

Subgroup

The Num

of studies

Pooled estimate

[SMD/MD (95 %CI)]

P value

I2(%)

Test for subgroup differences

global cognitive function

Treatment duration

≤ 12 months

7

0.35(-0.15, 0.84)

P = 0.17

87

P = 0.67

> 12 months

8

0.23(0.07, 0.40)

P = 0.006

91

 

participants

MCI patients

5

0.82(0.20, 1.45)

P = 0.01

95

P = 0.03*

EAWCI

10

0.13(0.03, 0.23)

P = 0.01

66

 

information processing speed

Treatment duration

≤ 12 months

5

-0.19(-0.38, 0.01)

P = 0.06

39

P = 0.007*

> 12 months

4

0.16(0.01, 0.31)

P = 0.04

64

 

participants

MCI patients

1

0.04(-0.28, 0.36)

P = 0.79

NA

P = 0.89

EAWCI

9

0.07(-0.13, 0.27)

P = 0.50

81

 

episodic memory

Treatment duration

≤ 12 months

7

-0.09(-0.27, 0.09)

P = 0.34

40

P = 0.09

> 12 months

6

0.08(0.02, 0.13)

P = 0.01

0

 

participants

MCI patients

4

0.42(-0.24, 1.08)

P = 0.21

94

P = 0.26

EAWCI

11

0.04(-0.04, 0.12)

P = 0.34

28

 

executive function

Treatment duration

≤ 12 months

4

0.01(-0.14, 0.17)

P = 0.87

0

P = 0.21

> 12 months

5

-0.29(-0.75, 0.16)

P = 0.20

96

 

participants

MCI patients

3

-0.33(-0.81, 0.15)

P = 0.18

89

P = 0.59

EAWCI

8

-0.17(-0.51, 0.17)

P = 0.34

94

 

Hcy

Treatment duration

≤ 12 months

7

-4.77(-6.28, -3.27)

P < 0.01

78

P = 0.68

> 12 months

5

-4.41(-5.27, -3.54)

P < 0.01

82

 

participants

MCI patients

3

-5.45(-6.51, -4.39)

P < 0.01

81

P = 0.05

EAWCI

8

-4.13(-4.93, -3.32)

P < 0.01

65

 
  1. Abbreviations: SMD standardized mean difference, MD mean difference, CI confidence interval,MCI mild cognitive impairment, EAWCI elderly adults without cognitive impairment, Hcy Homocysteine, NA not applicable
  2. *P < 0.05