Inhaled long acting β2 agonists v placebo for stable chronic asthma*
| Outcomes at 2–52 weeks | Weighted event rates | RRR (95% CI) | NNT (CI) | |
|---|---|---|---|---|
| β2 agonists | Placebo | |||
| *Abbreviations defined in glossary; weighted event rates, RRR, RRI, NNT, NNH, and CI calculated from data in article. | ||||
| Major exacerbation | 19% | 23% | 16% (9 to 23) | 25 (20 to 50) |
| RRI (CI) | NNH (CI) | |||
| Headache | 5.6% | 4.6% | 29% (1 to 66) | 100 (33 to ∞) |