2.

Subcutaneous sumatriptan 6 mg compared with placebo for acute cluster headache
Patient or population: adults with cluster headache Settings: community Intervention: subcutaneous sumatriptan 6 mg Comparison: placebo
Outcomes	Probable outcome with intervention	Probable outcome with comparator	NNT or NNTH and/or relative effect (95% CI)	No of studies, attacks, events	Quality of the evidence (GRADE)	Comments
Pain‐free at 30 mins	no data
Pain‐free at 15 mins	480 in 1000	170 in 1000	NNT 3.3 (2.4 to 5.0)	2 studies, 258 attacks, 85 events	Low
Headache relief at 30 mins	no data
Headache relief at 15 mins	750 in 1000	320 in 1000	NNT 2.4 (1.9 to 3.2)	2 studies, 258 attacks, 139 events	Low
At least one AE	340 in 1000	190 in 1000	NNH 6.6 (4.0 to 19)	2 studies, 293 attacks, 78 events	Very low
Serious AE	No events
CI: Confidence interval; NNT: number needed to treat; NNH: number needed to harm; AE: adverse event
GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate.

Evidence downgraded because of threat from potential publication bias and chance effects with modest effect size and small numbers of events.