Traditionally inhaled treatment for asthma has used separate preventer and reliever therapies. The combination of formoterol and budesonide in one inhaler has made possible a single inhaler for both prevention and relief of symptoms (single inhaler therapy or SiT).
To assess the efficacy and safety of budesonide and formoterol in a single inhaler for maintenance and reliever therapy in asthma compared with maintenance with inhaled corticosteroids (ICS) (alone or as part of current best practice) and any reliever therapy.
We searched the Cochrane Airways Group trials register in February 2013.
Parallel, randomised controlled trials of 12 weeks or longer in adults and children with chronic asthma. Studies had to assess the combination of formoterol and budesonide as SiT, against a control group that received inhaled steroids and a separate reliever inhaler.
Data collection and analysis
We used standard methodological procedures expected by Cochrane.
We included 13 trials involving 13,152 adults and one of the trials also involved 224 children (which have been separately reported). All studies were sponsored by the manufacturer of the SiT inhaler. We considered the nine studies assessing SiT against best practice to be at a low risk of selection bias, but a high risk of detection bias as they were unblinded.
In adults whose asthma was not well-controlled on ICS, the reduction in hospital admission with SiT did not reach statistical significance (Peto odds ratio (OR) 0.81; 95% confidence interval (CI) 0.45 to 1.44, eight trials, N = 8841, low quality evidence due to risk of detection bias in open studies and imprecision). The rates of hospital admission were low; for every 1000 people treated with current best practice six would experience a hospital admission over six months compared with between three and eight treated with SiT. The odds of experiencing exacerbations needing treatment with oral steroids were lower with SiT compared with control (OR 0.83; 95% CI 0.70 to 0.98, eight trials, N = 8841, moderate quality evidence due to risk of detection bias). For every 100 adults treated with current best practice over six months, seven required a course of oral steroids, whilst for SiT there would be six (95% CI 5 to 7). The small reduction in time to first severe exacerbation needing medical intervention was not statistically significant (hazard ratio (HR) 0.94; 95% CI 0.85 to 1.04, five trials, N = 7355). Most trials demonstrated a reduction in the mean total daily dose of ICS with SiT (mean reduction was based on self-reported data from patient diaries and ranged from 107 to 385 µg/day). Withdrawals due to adverse events were more common in people treated with SiT in comparison to current best practice (OR 2.85; 95% CI 1.89 to 4.30, moderate quality evidence due to risk of detection bias).
Three studies including 4209 adults compared SiT with higher dose budesonide maintenance and terbutaline for symptom relief. The studies were considered as low risk of bias. The run-in for these studies involved withdrawal of LABA, and patients were recruited who were symptomatic during run-in. The reduction in the odds of hospitalisation with SiT compared with higher dose ICS did not reach statistical significance (Peto OR; 0.56; 95% CI 0.28 to 1.09, moderate quality evidence due to imprecision). Fewer patients on SiT needed a course of oral corticosteroids (OR 0.54; 95% CI 0.45 to 0.64, high quality evidence). For every 100 adults treated with ICS over 11 months, 18 required a course of oral steroids, whilst for SiT there would be 11 (95% CI 9 to 12). Withdrawals due to adverse events were less common in people treated with SiT in comparison to higher dose budesonide maintenance (OR 0.57; 95% CI 0.35 to 0.93, high quality evidence).
One study included children (N = 224), in which SiT was compared with higher dose budesonide. There was a significant reduction in participants who needed an increase in their inhaled steroids with SiT, but there were only two hospitalisations for asthma and no separate data on courses of oral corticosteroids. Less inhaled and oral corticosteroids were used in the SiT group and the annual height gain was also 1 cm greater in the SiT group, (95% CI 0.3 cm to 1.7 cm).
The results for fatal serious adverse events were too rare to rule out either treatment being harmful. There was no significant difference found in non-fatal serious adverse events for any of the comparisons.
Single inhaler therapy has now been demonstrated to reduce exacerbations requiring oral corticosteroids against current best practice strategies and against a fixed higher dose of inhaled steroids. The strength of evidence that SiT reduces hospitalisation against these same treatments is weak. There were more discontinuations due to adverse events on SiT compared to current best practice, but no significant differences in serious adverse events. Our confidence in these conclusions is limited by the open-label design of the trials, and by the unknown adherence to treatment in the current best practice arms of the trials.
Single inhaler therapy can reduce the risk of asthma exacerbations needing oral corticosteroids in comparison with fixed dose maintenance ICS and separate relief medication. The reduced odds of exacerbations with SiT compared with higher dose ICS should be viewed in the context of the possible impact of LABA withdrawal during study run-in. This may have made the study populations more likely to respond to SiT.
Single inhaler therapy is not currently licensed for children under 18 years of age in the United Kingdom and there is currently very little research evidence for this approach in children or adolescents.