Table 2 Univariate risk factors for headache chronicity in patients with episodic migraine
| Risk factors | Odds ratio | 95% CI | p Value |
|---|---|---|---|
| Age, y, in quartiles | |||
| <34 | 1.00 | Referent | |
| 34–41 | 2.6 | 0.9–6.9 | 0.06 |
| 42–51 | 3.0 | 1.2–7.9 | 0.02 |
| >51 | 4.4 | 1.7–11.1 | 0.002 |
| Headache frequency, d | |||
| 0–4 | 1.00 | Referent | |
| 5–9 | 7.6 | 2.2–26.1 | 0.001 |
| ≥10–15 | 25.4 | 7.6–84.5 | 0.001 |
| Duration of primary headache, y | |||
| <14 | 1.00 | Referent | |
| 14–22 | 0.7 | 0.3–1.5 | 0.50 |
| >22 | 1.9 | 1.0–3.4 | 0.04 |
| Type of headache medication | |||
| None | 1.00 | Referent | |
| Analgesics | 2.7 | 0.6–11.7 | 0.19 |
| Ergots | 2.9 | 0.4–23.0 | 0.40 |
| Triptans | 3.7 | 0.8–16.4 | 0.09 |
| Opioids | 4.4 | 0.3–59.7 | 0.27 |
| Male | 1.5 | 0.8–2.9 | 0.21 |
| Headache medication overuse | 23.4 | 11.4–48.4 | 0.001 |
| >1 Headache medication used | 2.3 | 1.3–4.1 | 0.004 |
| Regular use of preventive medication | 2.5 | 1.4–4.3 | 0.001 |