Background: Asthma is a common chronic disease worldwide. Inhalers are often prescribed to help control asthma symptoms, improve quality of life and reduce the risk of exacerbations or flare-ups. However, evidence suggests that many people with asthma do not use their inhaler correctly. It is therefore important to evaluate whether interventions aimed specifically at improving technique are effective and safe, and whether use of these interventions translates into improved clinical outcomes.
Objectives: To assess the impact of interventions to improve inhaler technique on clinical outcomes and safety in adults and children with asthma.
Search methods: We searched the Cochrane Airways Trials Register, which contains records compiled from multiple electronic and handsearched resources. We also searched trial registries and reference lists of primary studies. We conducted the most recent search on 23 November 2016.
Selection criteria: We included studies comparing a group of adults or children with asthma receiving an inhaler technique intervention versus a group receiving a control or alternative intervention. We included parallel and cluster-randomised trials of any duration conducted in any setting, and planned to include only the first phase of any cross-over trials identified. We included studies reported as full-text articles, those published as abstracts only and unpublished data.
Data collection and analysis: Two review authors screened the search results for eligible studies. We extracted outcome data, assessed risk of bias in duplicate and resolved discrepancies by involving another review author. We grouped studies making similar comparisons by consensus (e.g. all those comparing enhanced inhaler technique education vs usual care) and conducted meta-analyses only if treatments, participants and the underlying clinical question were similar enough for pooling to make sense. We analysed dichotomous data as odds ratios, and continuous data as mean differences or standardised mean differences, all with random-effects models. We described skewed data narratively. We graded the results and presented evidence in 'Summary of findings' tables for each comparison. Primary outcomes were inhaler technique, asthma control and exacerbations requiring at least oral corticosteroids (OCS).
Main results: This review includes 29 parallel randomised controlled trials (RCTs) (n = 2210), although not all reported relevant or useable data. All participants had asthma, and follow-up ranged from 2 to 26 weeks. Most studies were at low or unclear risk of selection and attrition biases and at high risk for biases associated with blinding. We considered most of the evidence to be of low quality owing to these biases and to imprecision in the estimates of effect.We classified studies into three comparisons: enhanced face-to-face training session(s), multi-media-delivered inhaler training (e.g. DVD, computer app or game) and technique feedback devices. Differences between interventions, populations and outcome measures limited quantitative analyses, particularly for exacerbations, adverse events, unscheduled visits to a healthcare provider and absenteeism from work or school.Enhanced inhaler technique education and multi-media training improved technique in most studies immediately after the intervention and at follow-up, although the variety of checklists used meant that this was difficult to assess reliably. For both adults and children, how and when inhaler technique was assessed appeared to affect whether inhaler technique improved and by how much.Analyses of the numbers of people who demonstrated correct or 'good enough' technique were generally more useful than checklist scores. Adult studies of enhanced education showed benefit when this metric was used at 2 to 26 weeks' follow-up (odds ratio (OR) 5.00, 95% confidence interval (CI) 1.83 to 13.65; 258 participants; three studies; 31 per 100 with correct technique in the control group compared with 69 (95% CI 45 to 86) in the education group; moderate-quality evidence). A similar result was seen in studies looking at feedback devices at four weeks' follow-up (OR 4.80, 95% CI 1.87 to 12.33; 97 participants; one study; 51 per 100 with correct technique in the control group compared with 83 (95% CI 66 to 93) in the feedback group; low-quality evidence). However, the benefit of multi-media training for adults even immediately after the intervention was uncertain (OR 2.15, 95% CI 0.84 to 5.50; 164 participants; two studies; I² = 49%; 30 per 100 in the control group with correct technique compared with 47 (95% CI 26 to 70) in the multi-media group; moderate-quality evidence). Evidence tended to be less clear for children, usually because results were based on fewer and smaller studies.Some studies did not report exacerbations in a way that allowed meta-analysis; others provided inconclusive results. Inhaler technique interventions provided some benefit for asthma control and quality of life but generally did not lead to consistent or important clinical benefits for adults or children. Confidence intervals included no difference or did not reach a threshold that could be considered clinically important. Responder analyses sometimes showed improvement among more people in the intervention groups, even though the mean difference between groups was small. We found no evidence about harms.
Authors' conclusions: Although interventions to improve inhaler technique may work in some circumstances, the variety of interventions and measurement methods used hampered our ability to perform meta-analyses and led to low to moderate confidence in our findings. Most included studies did not report important improvement in clinical outcomes. Guidelines consistently recommend that clinicians check regularly the inhaler technique of their patients; what is not clear is how clinicians can most effectively intervene if they find a patient's technique to be inadequate, and whether such interventions will have a discernible impact on clinical outcomes.