Table 2 Effect of folic acid treatment on first stroke risk, stratified by MTHFR C677T genotypes and plateletcrit

From: Effect of plateletcrit and methylenetetrahydrofolate reductase (MTHFR) C677T genotypes on folic acid efficacy in stroke prevention

MTHFR C677T genotypes subgroups

Enalapril group

Enalapril–folic acid group

NNT

Unadjusted model

Adjusted model

TT genotype

Total

Events(%)

Total

Events(%)

 

HR(95% CI)

p value

p value for interaction

HR(95% CI)

p value

p value for interaction*

Total stroke

Total

1507

66(4.4)

1505

56(3.7)

143

0.85(0.60, 1.22)

0.380

 

0.87(0.61, 1.24)

0.442

 

PCT Q1

393

22(5.6)

363

7(1.9)

27

0.34(0.15, 0.81)

0.014

Ref

0.34(0.14, 0.82)

0.016

Ref

PCT Q2–Q4

1114

44(4.0)

1142

49(4.3)

–

1.09(0.73, 1.64)

0.669

0.011

1.09(0.72, 1.64)

0.681

0.021

PCT Q2

359

9(2.5)

371

16(4.3)

–

1.73(0.80, 3.93)

0.186

 

1.62(0.71, 3.72)

0.254

 

PCT Q3

380

18(4.7)

404

16(4.0)

143

0.85(0.43, 1.67)

0.634

 

0.866(0.44,1.72)

0.678

 

PCT Q4

375

17(4.5)

367

17(4.6)

–

1.01(0.52, 1.99)

0.967

 

0.90(0.45, 1.80)

0.763

 

Ischemic stroke

Total

1507

56(3.7)

1505

51(3.4)

333

0.92(0.63, 1.34)

0.650

 

0.94(0.65, 1.38)

0.767

 

PCT Q1

393

20(5.1)

363

6(1.7)

29

0.32(0.13, 0.81)

0.016

Ref

0.33(0.13, 0.83)

0.019

Ref

PCT Q2–Q4

1114

36(3.2)

1142

45(3.9)

–

1.23(0.79, 1.90)

0.359

0.010

1.23(0.79, 1.91)

0.353

0.018

PCT Q2

359

8(2.2)

371

13(3.5)

–

1.58(0.65, 3.81)

0.310

 

1.62(0.66, 3.97)

0.292

 

PCT Q3

380

12(3.2)

404

15(3.7)

–

1.20(0.56, 2.56)

0.643

 

1.23(0.57, 2.66)

0.606

 

PCT Q4

375

16(4.3)

367

17(4.6)

–

1.08(0.55, 2.14)

0.827

 

0.95(0.47, 1.93)

0.888

 

CC&CT genotype

Total stroke

Total

4076

153(3.8)

4097

110(2.7)

91

0.71(0.56, 0.91)

0.006

 

0.71(0.56, 0.91)

0.006

 

PCT Q1

1084

45(4.2)

1044

18(1.7)

40

0.41(0.24,0.70)

0.001

Ref

0.40(0.23, 0.70)

0.001

Ref

PCT Q2–Q4

2992

108(3.6)

3053

92(3.0)

167

0.83(0.63, 1.10)

0.201

0.021

0.83(0.63, 1.10)

0.194

0.023

PCT Q2

984

30(3.0)

997

27(2.7)

333

0.89(0.53, 1.49)

0.649

 

0.92(0.55, 1.56)

0.759

 

PCT Q3

1003

37(3.7)

1016

33(3.2)

200

0.88(0.55, 1.41)

0.604

 

0.84(0.52, 1.35)

0.467

 

PCT Q4

1005

41(4.1)

1040

32(3.1)

100

0.75(0.47, 1.19)

0.226

 

0.69(0.43, 1.10)

0.117

 

Ischemic stroke

Total

4076

134(3.3)

4097

92(2.2)

90

0.68(0.52, 0.89)

0.004

 

0.67(0.52, 0.88)

0.004

 

PCT Q1

1084

41(3.8)

1044

12(1.1)

37

0.30(0.16, 0.56)

<0.001

Ref

0.30(0.16, 0.57)

<0.001

Ref

PCT Q2–Q4

2992

93(3.1)

3053

80(2.6)

200

0.84(0.63, 1.14)

0.262

0.004

0.83(0.62, 1.13)

0.235

0.005

PCT Q2

984

24(2.4)

997

25(2.5)

–

1.03(0.59, 1.8)

0.923

 

1.07(0.61, 1.88)

0.818

 

PCT Q3

1003

34(3.4)

1016

29(2.9)

200

0.84(0.52, 1.39)

0.504

 

0.80(0.49, 1.32)

0.384

 

PCT Q4

1005

35(3.5)

1040

26(2.5)

100

0.72(0.43, 1.19)

0.195

 

0.64(0.38, 1.07)

0.088

 
  1. PCT Q1 (≤0.16%), Q2–Q4 (>0.16%), PCT Q2 (>0.16%–≤0.186%), PCT Q3 (>0.186%–≤0.217%), PCT Q4 (>0.217%). Variables in the adjusted model include age, sex, smoking status, body mass index, systolic blood pressure, diastolic blood pressure, total cholesterol, triglycerides, high-density lipoprotein cholesterol, total homocysteine, creatinine, and blood glucose. Enalapril group is the reference group
  2. CI confidence interval, HR hazard ratio, MTHFR methylenetetrahydrofolate reductase, NNT number needed to treat, PCT plateletcrit, Q quartile
  3. *p value for interaction test: two-way interaction of PCT (Q1 vs. Q2–Q4) and treatment groups (enalapril vs. enalapril-folic acid) on first stroke
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