Table 3 Pairwise analyses of odds ratios (with 95 % confidence intervals) for future classification in latent class 3 (LC3) with FM symptoms (in 1990) in twin pairs discordant for this classification (LC3 vs. LC1). Predictors are assessed from 1981

back pain (yes/no)

2.7 (1.4–5.2)

117

2.3 (1.1–4.6)

86

5.0 (0.6–42.8)

23

shoulder pain (yes/no)

3.1 (1.3–7.4)

91

8.0 (1.8–34.8)

64

1.0 (0.3–3.5)

23

neck pain (yes/no)

4.0 (1.5–10.7)

92

5.0 (1.4–17.3)

64

2.0 (0.4–10.9)

24

poor sleep

1.4 (0.4–4.4)

144

1.3 (0.3–6.0)

104

1.5 (0.3–9.0)

31

good sleep

1.0 reference category

1.0

1.0

BMI

143

103

31

 overweight

1.9 (1.0–3.8)

1.6 (0.8–3.3)

5.0 (0.6–42.8)

 underweight

0.5 (0.0–5.5)

0.5 (0.0–5.5)

omitted^a

 normal weight

1.0 reference category

1.0

1.0

headache (yes/no)

2.1 (1.0–4.1)

132

2.2 (1.0–4.9)

97

2.5 (0.5–12.9)

27