| Outcomes | Illustrative comparative risks# (95% CI) | Relative effect (95% CI) | No of Participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk: nebuliser | Corresponding risk: multiple treatment of β2-agonist via spacer (chamber) | |||||
| Hospital admission | 110 per 1000 | 78 per 1000 (52 to 119) | RR 0.71 (0.47 to 1.08) | 757 (9 studies) | ++ Low¶,§ | Large increases in the proportion of children admitted to hospital on spacer in comparison to nebuliser are ruled out by this 95% confidence interval. |
| Duration in emergency department min | The mean duration in emergency department (minutes) in the control groups was 103 minutes | The mean duration in emergency department (minutes) in the intervention groups was 33 minutes shorter (43 minutes shorter to 24 minutes shorter) | 396 (3 studies) | +++ Moderate¶ | There was a consistent direction of shortening of time in the emergency department in all three studies and, although the size of this effect varied between studies (I2 = 66%), we felt that the mean difference was important in all studies. | |
| Final rise in FEV1 % pred | Control groups: 27% predicted at baseline | Intervention groups: 0.92% higher (4.96% lower to 6.79% higher) | 48 (2 studies) | ++ Low¶,§ | ||
| Mean rise in pulse rate % baseline | Control groups: 7% rise from baseline | Intervention groups: 5.62% lower (7.52% to 3.72% lower) | 670 (9 studies) | +++ Moderate¶ | ||
| Number of participants developing tremor | 142 per 1000 | 91 per 1000 (62 to 135) | RR 0.64 (0.44 to 0.95) | 254 (4 studies) | +++ Moderate¶ | |
#: The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes, the corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI); ¶: Mostly open label studies; §: Wide confidence intervals. Patient or population: children with acute asthma; settings: community or emergency department; intervention: multiple treatments with β2-agonist via spacer (chamber); comparison: multiple treatments with β2-agonist via nebuliser. GRADE Working Group grades of evidence are as follows: 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.