The review concluded that the SMART (single inhaler maintenance and reliever) approach using formoterol-budesonide was superior in preventing asthma exacerbations when compared with traditional therapy, without any increase in adverse events. Despite some methodological limitations of the review, the authors' conclusions reflect the evidence and are likely to be reliable.

To evaluate the efficacy and safety of the SMART (single inhaler maintenance and reliever) approach using formoterol-budesonide versus other approaches for the prevention of asthma exacerbations.

MEDLINE and EMBASE were searched from 1988 to 2008 for articles published in English. Search terms were reported. Reference lists of review articles and selected papers were searched manually. The personal files of authors were also reviewed.

Randomised controlled trials (RCTs) that compared the SMART approach (using formoterol-budesonide combination) with control treatments in patients with asthma were eligible for inclusion. The control group had to be inhaled corticosteroids or inhaled corticosteroids combined plus long-acting beta agonists as maintenance, with a rapid acting beta-2 agonist as reliever. The relevant outcomes were asthma exacerbations and adverse events.

The included trials compared the SMART approach (primarily turbuhaler) with various inhaled corticosteroids or inhaled corticosteroids plus long-acting beta agonists approaches. The doses and dosing regimens varied across trials. The mean baseline forced expiratory volume in the first second (FEV₁) of participants ranged from 70 to 95%. The mean age of included patients ranged from 35 to 45.

Two reviewers independently performed study selection; disagreements were resolved through discussion.

Quality assessment was undertaken using the Jadad criteria, which assessed five quality factors: randomisation, blinding, withdrawals/drop-outs, method of blinding described, and randomisation method. Trials that scored at least 3 out of 5 points on the Jadad scale were considered high quality.

The authors did not state how many reviewers performed the quality assessment.

Data were extracted on asthma exacerbations and adverse events and used to calculate odds ratios (ORs) with 95% confidence intervals (CIs).

The authors did not state how many reviewers performed the data extraction.

The pooled odds ratios were calculated using a random-effects meta-analysis. The number needed to treat (NNT) was also estimated. Statistical heterogeneity was assessed using the I² and X² tests. Sensitivity analysis was conducted by omitting trials that were not blinded from the analysis.

Eight RCTs were included in the review (the overall number of participants was not reported). Two RCTs scored 2 out of 5 on the quality assessment and were deemed low quality; the remaining six trials scored at least 3 out of 5 and were deemed high quality. All of the trials were randomised; most used an adequate method of randomisation. The method of blinding was adequately described in only a few trials.

SMART versus fixed-dose inhaled corticosteroids plus long-acting beta agonists: Compared with inhaled corticosteroids plus long-acting beta agonists, the SMART approach (using formoterol-budesonide) had statistically lower rates of severe exacerbations (OR 0.65, 95% CI 0.53 to 0.80; I²=77%; NNT=18; six RCTs; n=14,536 patients) and severe exacerbations requiring hospitalisation/and or emergency room treatment (OR 0.69, 95% CI 0.58 to 0.83; I²=0%; NNT=53; five RCTs; n=12,702). There was no statistically significant difference in the rates of all adverse events or serious adverse events between the two treatment groups.

SMART versus fixed-dose inhaled corticosteroids: Compared with inhaled corticosteroids, the SMART approach had statistically lower rates of severe exacerbations (OR 0.52, 95% CI 0.45 to 0.61; I²=0%; NNT=10; three RCTs; n=4,437) and severe exacerbations requiring medical intervention (OR 0.52, 95% CI 0.42 to 0.65; I²=36%; NNT= 12; two RCTs; n=3,724). There was no statistically significant difference in the rates of all adverse events or serious adverse events between SMART and inhaled corticosteroids.

The SMART approach using formoterol-budesonide was superior in preventing exacerbations when compared with traditional therapy with fixed-dose inhaled corticosteroids or inhaled corticosteroids plus long-acting beta agonists, without any increase in adverse events.

Inclusion criteria for the review were clearly defined. Two relevant databases were searched. There was the potential for both publication bias and language bias, as only published English language articles were included; publication bias was not assessed. The authors attempted to minimise reviewer error and bias during study selection, but did not state if such attempts were made for quality assessment and data extraction.

Quality assessment was based on a standard Jadad checklist, although the assertion of high quality based on a score of 3 or more points may be too generous. Trials were pooled using a random-effects meta-analysis; statistical heterogeneity was explored, which appeared appropriate. However, there was still statistical heterogeneity in two of the key analyses, which the authors acknowledged.

Despite some methodological limitations of the review, the authors' conclusions reflect the evidence and are likely to be reliable.

Practice: The authors stated that SMART therapy should probably be adopted as the standard of care for asthma patients.

Research: The authors stated that as all of the trials have been conducted by a single sponsor, an individual patient data meta-analysis would be feasible and would strengthen the results of the review.

Not stated.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.