Table 4 The number of concordant and discordant monozygotic (MZ) and same gender dizygotic (DZ) twin pairs with tension-type headache (from [26])

No

Number of pairs

Concordant pairs

143

146

61

41

204

187

Discordant pairs

285

431

116

169

401

600

Concordance rate

Probandwise

50

40

51

33

50

38

95% CI

(43–57)

(33–48)

(40–62)

(20–46)

(45–56)

(32–45)

p-values

<0.001

<0.001

<0.001

Infrequent episodic

Number of pairs

Concordant pairs

630

757

674

642

1,304

1,399

Discordant pairs

413

539

377

519

790

1,058

Concordance rate

Probandwise

75

74

78

71

77

73

95% CI

(73–78)

(71–76)

(76–81)

(68–74)

(75–79)

(71–74)

p-values

n.s.

<0.001

<0.001

Frequent episodic

Number of pairs

Concordant pairs

40

20

148

119

188

139

Discordant pairs

153

188

297

401

450

589

Concordance rate

Probandwise

34

18

50

37

46

32

95% CI

(21–48)

(2–34)

(43–57)

(29–45)

(39–52)

(25–39)

p-values

<0.001

<0.001

<0.001

Chronic

Number of pairs

Concordant pairs

0

0

1

1

1

1

Discordant pairs

7

6

11

15

18

21

Concordance rate

Probandwise

0

0

15

12

10

9

95% CI

(−)

(−)

(−52−83)

(−50−73)

(−47−67)

(−45−63)

p-values

–

n.s.

n.s.

Migraine without aura

Concordance rate

Probandwise [27, 28]

29

15

50

37

43

31

95% CI

(3–55)

(–19–49)

(41–59)

(31–43)

(37–49)

(26–36)

Migraine with aura

Concordance rate

Probandwise [29, 30]

53

29

48

15

50

21

95% CI

(35–71)

(15–43)

(32–64)

(4–26)

(38–62)

(12–30)