Summary of relative risk (95% CI) between migraine and ischaemic stroke in five meta-analyses of observational studies
| Etminan et al 4 | Schurks et al 5 | Spector et al 6 | Hu et al 7 | Mahmoud et al 8 | |
| Number of studies (total) | 14 | 25 | 21 | 11 | 16 |
| Number of participants | — | — | 622 381 | 2 221 888 | 1 152 407 |
| Outcome | Migraine and risk of ischaemic stroke | Migraine and risk of cardiovascular disease | Migraine and risk of ischaemic stroke | Migraine and risk of stroke | Migraine and risk of cardiovascular and cerebrovascular events |
| Overall migraine | |||||
| All studies | 2.16 (1.89–2.48) | 1.73 (1.31–2.29) | 2.04 (1.72–2.43) | ||
| Case–control studies | 2.18 (1.86–2.56) | 1.96 (1.39–2.76) | — | ||
| Cohort studies | 2.10 (1.61–2.75) | 1.47 (0.95–2.27) | — | 1.64 (1.22–2.20) | 1.32 (1.03–1.68)† |
| Women | — | 2.08 (1.13–3.84) | — | — | — |
| Men | — | 1.37 (0.89–2.11) | — | — | — |
| Women and men <45 years | 2.36 (1.92–2.90) | 2.65 (1.41–4.97) | — | — | — |
| Women <45 years | 2.76 (2.17–3.52) | 3.65 (2.21–6.04) | — | — | — |
| Oral contraceptive use | 8.72 (5.05–15.05) | 7.02 (1.51–32.68) | — | — | — |
| Smoking | — | 9.03 (4.22–19.34) | — | — | — |
| Migraine with aura | 2.27 (1.61–3.19) | 2.16 (1.53–3.03) | 2.41 (1.81–3.43) | 2.14 (1.33–3.43) | 1.56 (1.30–1.87)† |
| Smoking | — | 1.5 (1.1–2.3)* | — | — | — |
| Women currently using oral contraceptives and smoke | — | 10.0 (1.4–73.7)* | — | — | — |
| Migraine without aura | 1.83 (1.06–3.15) | 1.23 (0.90–1.69) | 1.52 (0.99–2.35) | 1.02 (0.68–1.51) | 1.11 (0.94–1.31)† |
— not reported.
* estimate provided by only one study.
† outcome reported as stroke (haemorragic and ischaemic). Two studies on ischaemic stroke only.