The quality of evidence is downgraded by study limitations (unclear allocation concealment), and by imprecise results (few patients and outcome events).
A Cochrane review [Abstract] 1 included 6 studies with a total of 490 preschool children, 145 school-aged children and 240 adults with asthma. Included studies compared the efficacy and safety of patient-initiated intermittent inhaled corticosteroid (ICS) therapy used at the onset of an exacerbation (recognised as separate or combined treatment with a short-acting beta2-agonist reliever) and compared with placebo in the management of children and adults diagnosed with, or suspected to have, symptoms of mild persistent asthma. Study durations were 12 to 52 weeks.Results for preschool children were presented in a separate analysis as this represents a distinct clinical condition, not necessarily related to the development of long term asthma.
There was a statistically non-significant reduction in the risk of patients experiencing one or more exacerbations requiring oral corticosteroids in older children and adults with asthma (table T1). No difference was observed in the risk of adverse events. There was insufficient number of participants to make firm conclusions whether the intermittent ICS group displayed any reduction in the rate of hospitalisations, or day time and night time symptoms scores. Lung function tests reported by a single study favoured the use of ICS. There was no significant group difference in growth rate of children, or overall withdrawals.
| Outcome | Relative effect (95% CI) | Assumed risk - placebo | Corresponding risk - ICS (95% CI) | Participants (studies) |
|---|---|---|---|---|
| Exacerbations requiring oral corticosteroids - school-age children | OR 0.57(0.29 to 1.12) | 486 per 1000 | 351 per 1000(216 to 515) | 145 (1 study) |
| Exacerbations requiring oral corticosteroids - adults | OR 0.10(0.01 to 1.95) | 34 per 1000 | 3 per 1000(0 to 64) | 240 (1 study) |
| Serious adverse events | OR 1 (0.14 to 7.25) | 5 per 1000 | 5 per 1000(1 to 37) | 385 (2 studies) |
| Adverse events | OR 2.90(0.12 to 71.96) | 0 per 1000 | 0 per 1000 (0 to 0) | 243 (1 study) |
In preschool children with frequent wheezing episodes, the use of intermittent ICS at the onset of early symptoms reduced the likelihood of requiring rescue oral corticosteroids by half (table T2). There was no difference in hospitalisations or in a single study measuring parent perceived quality of life. Intermittent therapy was associated with improvements in both day time and night time symptoms. There was no increase in the rates of withdrawals, and overall and treatment-specific adverse events. There seemed to be fewer serious adverse events in preschool children who received ICS compared with the placebo group although the difference was not statistically significant.
| Outcome | Relative effect (95% CI) | Assumed risk - placebo | Corresponding risk - ICS (95% CI) | Participants (studies) |
|---|---|---|---|---|
| Exacerbations requiring oral corticosteroids | OR 0.48(0.31 to 0.73) | 434 per 1000 | 269 per 1000(192 to 359) | 490(4 studies) |
| Hospitalisations | OR 0.73(0.23 to 2.29) | 149 per 1000 | 113 per 1000(39 to 286) | 327(3 studies) |
| Quality of Life | The mean quality of life in the intervention groups was3.28 higher(-2.13 to 8.69 higher) | 143 (1 study) | ||
| Day time asthma score | The mean daytime asthma score in the intervention groups was0.35 standard deviations lower(0.57 to 0.13 lower) | 364 (3 studies) | ||
| Night time asthma score | The mean nighttime asthma score in the intervention groups was0.28 standard deviations lower(0.50 to 0.06 lower) | 364 (3 studies) | ||
| Serious adverse events | OR 0.42(0.17 to 1.02) | 82 per 1000 | 36 per 1000(15 to 83) | 439 (3 studies) |
| Adverse events | OR 0.86(0.42 to 1.75) | 304 per 1000 | 273 per 1000(155 to 433) | 166 (1 study) |
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