Abstract: This review update added three new studies including 419 participants to the review. In total, we identified eight RCTs, most of which were at low risk of bias, involving 1669 participants with mild to moderate asthma. We included three paediatric (n = 422) and five adult (n = 1247) studies; six were parallel-group trials and two had a cross-over design. All but one study followed participants for six months to one year. Allowed maintenance doses of ICS varied in adult and paediatric studies, as did use of concomitant medications and doses of ICS initiated during exacerbations. Investigators gave participants a study inhaler containing additional ICS or placebo to be started as part of an action plan for treatment of exacerbations. The odds of treatment failure, defined as the need for oral corticosteroids, were not significantly reduced among those randomised to increased ICS compared with those taking their usual stable maintenance dose (odds ratio (OR) 0.89, 95% confidence interval (CI) 0.68 to 1.18; participants = 1520; studies = 7). When we analysed only people who actually took their study inhaler for an exacerbation, we found much variation between study results but the evidence did not show a significant benefit of increasing ICS dose (OR 0.84, 95% CI 0.54 to 1.30; participants = 766; studies = 7). The odds of having an unscheduled physician visit (OR 0.96, 95% CI 0.66 to 1.41; participants = 931; studies = 3) or acute visit (Peto OR 0.98, 95% CI 0.24 to 3.98; participants = 450; studies = 3) were not significantly reduced by an increased versus stable dose of ICS, and evidence was insufficient to permit assessment of impact on the duration of exacerbation; our ability to draw conclusions from these outcomes was limited by the number of studies reporting these events and by the number of events included in the analyses. The odds of serious events (OR 1.69, 95% CI 0.77 to 3.71; participants = 394; studies = 2) and non-serious events, such as oral irritation, headaches and changes in appetite (OR 2.15, 95% CI 0.68 to 6.73; participants = 142; studies = 2), were neither increased nor decreased significantly by increased versus stable doses of ICS during an exacerbation. Too few studies are available to allow firm conclusions on the basis of subgroup analyses conducted to investigate the impact of age, time to treatment initiation, doses used, smoking history and the fold increase of ICS on the magnitude of effect; yet, effect size appears similar in children and adults. Current evidence does not support increasing the dose of ICS as part of a self initiated action plan to treat exacerbations in adults and children with mild to moderate asthma. Increased ICS dose is not associated with a statistically significant reduction in the odds of requiring rescue oral corticosteroids for the exacerbation, or of having adverse events, compared with a stable ICS dose. Wide confidence intervals for several outcomes mean we cannot rule out possible benefits of this approach.

Plain-language summary: This review update added three new studies including 419 participants to the review. We performed the most recent searches in March 2016. In total, we found eight studies involving 1669 people with mild or moderate asthma. Three were conducted in children, and five in adults. These studies provided participants with an inhaler that contained extra doses of ICS (to increase their usual ICS dose) or a placebo that could be used if their symptoms worsened. Participants were then followed for six months to one year to see whether people taking more inhaled corticosteroids during attacks did better than those who took a placebo. People taking an increased dose of ICS during an attack did not do better than those who took a placebo, regardless of whether we looked at all study participants or only those who actually took the inhalers during an attack. Results showed a lot of variation in studies that focused only on people who took the inhalers, with some studies showing benefit of increasing ICS dose and others showing no benefit. It is unlikely that increasing ICS dose reduces the need for a course of oral steroids to treat the attack, prevents the need for an emergency visit with doctors or at the hospital or reduces the time it takes to recover. We cannot be sure of these last results because few studies reported them. Use of either strategy was not associated with significantly more or less serious and non-serious side effects, but again we cannot say for sure because we did not find enough studies. We have rated results of this review as having moderate or low quality, depending on the outcome. This means that some of the findings were very uncertain, mainly because the studies included very few people who could say definitively whether increasing the dose was better or worse than, or no different from, keeping the dose stable.