Table 2 Odds ratio (OR) with 95% confidence interval (CI) of high sensitivity C-reactive protein (hs-CRP) defined as > 3.0–20.0 mg/l related to headache types

No headache

1.00

1.00

1.00

Any headache

1.11 (1.05–1.17)

1.07 (1.01–1.13)

1.05 (1.00–1.11)

 < 1 days/month

1.02 (0.95–1.11)

0.99 (0.91–1.07)

0.97 (0.90–1.08)

 1–6 days/month

1.06 (0.99–1.13)

1.01 (0.95–1.08)

0.99 (0.93–1.07)

 7–14 days/month

1.28 (1.14–1.44)

1.21 (1.08–1.37)

1.15 (1.04–1.30)

 ≥ 15 days/month

1.40 (1.21–1.62)

1.32 (1.13–1.53)

1.26 (1.08–1.48)

 P trend

< 0.001

0.001

0.01

Migraine

1.23 (1.13–1.34)

1.17 (1.07–1.28)

1.14 (1.04–1.25)

 < 1 days/month

0.99 (0.89–1.10)

0.94 (0.84–1.05)

0.92 (0.82–1.02)

 1–6 days/month

1.19 (1.07–1.31)

1.12 (1.01–1.25)

1.10 (1.00–1.23)

 7–14 days/month

1.36 (1.12–1.64)

1.32 (1.09–1.60)

1.24 (1.02–1.51)

 ≥ 15 days/month

1.88 (1.42–2.50)

1.72 (1.29–2.31)

1.62 (1.21–2.17)

 P trend

< 0.001

< 0.001

0.01

MA

1.26 (1.13–1.40)

1.24 (1.11–1.39)

1.15 (1.03–1.29)

 < 1 days/month

1.01 (0.90–1.13)

0.95 (0.85–1.07)

0.93 (0.82–1.04)

 1–6 days/month

1.19 (1.05–1.35)

1.13 (0.99–1.28)

1.09 (0.96–1.24)

 7–14 days/month

1.56 (1.23–1.96)

1.51 (1.19–1.91)

1.40 (1.11–1.77)

 ≥ 15 days/month

2.15 (1.50–3.08)

2.01 (1.39–2.90)

1.84 (1.27–2.67)

 P trend

< 0.001

< 0.001

0.002

MO

1.17 (1.03–1.32)

1.12 (0.99–1.27)

1.09 (0.96–1.24)

 < 1 days/month

0.99 (0.88–1.11)

0.94 (0.84–1.06)

0.92 (0.82–1.04)

 1–6 days/month

1.18 (1.03–1.35)

1.14 (0.99–1.31)

1.13 (0.98–1.30)

 7–14 days/month

1.10 (0.79–1.52)

1.08 (0.77–1.50)

1.03 (0.74–1.44)

 ≥ 15 days/month

1.58 (0.99–2.51)

1.42 (0.88–2.28)

1.37 (0.85–2.22)

 P trend

0.01

0.12

0.23

Other headaches

1.08 (1.02–1.14)

1.04 (0.98–1.11)

1.04 (0.97–1.10)

 < 1 days/month

1.05 (0.96–1.14)

1.01 (0.93–1.10)

1.00 (0.92–1.09)

 1–6 days/month

1.03 (0.96–1.11)

1.00 (0.93–1.07)

0.98 (0.91–1.05)

 7–14 days/month

1.28 (1.11–1.47)

1.20 (1.04–1.39)

1.15 (1.00–1.33)

 ≥ 15 days/month

1.29 (1.09–1.53)

1.23 (1.04–1.46)

1.18 (0.99–1.41)

 P trend

< 0.001

0.03

0.16