Which long-acting inhaled drugs, used alone or in combination, are the most effective for people with COPD?

Why is this question important?

Inhaled drugs for COPD have been shown to relieve symptoms, improve quality of life and prevent or treat flare-ups. Treatment with these inhaled drugs tends to begin with one inhaler, and additional therapies are introduced as necessary. For persistent or worsening symptoms, long-acting inhaled drugs taken once or twice daily are preferred over short-acting ones. Several Cochrane reviews have looked at the risks and benefits of specific long-acting inhaled therapies compared with placebo or other treatments. However for patients and clinicians, it is important to understand the benefits of these treatments relative to each other, and whether a particular type of inhaled therapy is more beneficial than the others.

How did we answer the question?
We looked for studies in existing Cochrane reviews and performed detailed electronic searches up to September 2013. Studies were included if they lasted at least six months and compared any of the following treatments versus any other for people with COPD: long-acting beta2-agonists (LABAs—formoterol, indacaterol, salmeterol); long-acting muscarinic antagonists (LAMAs—aclidinium, glycopyrronium, tiotropium); inhaled corticosteroids (ICSs—budesonide, fluticasone, mometasone); combination long-acting beta2-agonist and inhaled corticosteroid (LABA/ICS—formoterol/budesonide, formoterol/mometasone, salmeterol/fluticasone); and placebo.

We conducted a network meta-analysis to assess the benefits of each type of treatment (e.g. long-acting beta2-agonists) relative to the others for quality of life and lung function. We also looked at how much individual treatments varied (e.g. How different were the three inhaled steroids from one other?) and whether particular treatments were more effective than others. We assessed the data for six months and 12 months separately and reported six months as the primary findings.

What did we find?
We found 71 relevant studies, but not all measured the outcomes we were interested in. Forty-two studies were included in the quality of life analyses (measured on St George's Respiratory Questionnaire), and 46 were included in the lung function analyses.

Evidence from good quality and similar trials supported LABA/ICS combinations as the most likely treatment strategy to bring the greatest improvement to quality of life and lung function. Combination therapy gave an average benefit of 3.9 units over placebo at six months. LAMAs and LABAs were ranked second and third at six months (-2.63 and -2.29 units, respectively), especially when unreliable trials were not included, but a large degree of overlap in the estimates was noted.

Combination LABA/ICS was the highest ranked class for trough forced expiratory volume in one second (FEV1), with mean improvement over placebo of 133 mL at six months (95% credible Interval (CrI) 101 to 164). As was the case for SGRQ, LAMAs (mean difference (MD) 104, 95% CrI 82 to 125) were ranked just ahead of LABAs (MD 99, 95% CrI 72 to 128) at six months, and ICSs were the lowest ranked class (MD 65, 95% CrI 33 to 97).

For both outcomes, the effects of LABA and ICS used alone appeared to increase when used together for six months, but initial differences between the treatment classes were less obvious after a year of treatment.

Conclusion
Quality of life and lung function were improved most on combination inhalers (LABA and ICS) and least on ICS alone at 6 and 12 months. Overall LAMA and LABA inhalers had similar effects, particularly at 12 months. The network has demonstrated the benefit of ICS when added to LABA for these outcomes in participants who largely had an FEV1 that was less than 50% predicted, but the additional expense of combination inhalers and any potential for increased adverse events (which has been shown by other reviews) require consideration. Our findings are in keeping with current National Institute for Health and Care Excellence (NICE) guidelines.

Authors' conclusions: 

This network meta-analysis compares four different classes of long-acting inhalers for people with COPD who need more than short-acting bronchodilators. Quality of life and lung function were improved most on combination inhalers (LABA and ICS) and least on ICS alone at 6 and at 12 months. Overall LAMA and LABA inhalers had similar effects, particularly at 12 months. The network has demonstrated the benefit of ICS when added to LABA for these outcomes in participants who largely had an FEV1 that was less than 50% predicted, but the additional expense of combination inhalers and any potential for increased adverse events (which has been established by other reviews) require consideration. Our findings are in keeping with current National Institute for Health and Care Excellence (NICE) guidelines.

Read the full abstract...
Background: 

Pharmacological therapy for chronic obstructive pulmonary disease (COPD) is aimed at relieving symptoms, improving quality of life and preventing or treating exacerbations.

Treatment tends to begin with one inhaler, and additional therapies are introduced as necessary. For persistent or worsening symptoms, long-acting inhaled therapies taken once or twice daily are preferred over short-acting inhalers. Several Cochrane reviews have looked at the risks and benefits of specific long-acting inhaled therapies compared with placebo or other treatments. However for patients and clinicians, it is important to understand the merits of these treatments relative to each other, and whether a particular class of inhaled therapies is more beneficial than the others.

Objectives: 

To assess the efficacy of treatment options for patients whose chronic obstructive pulmonary disease cannot be controlled by short-acting therapies alone. The review will not look at combination therapies usually considered later in the course of the disease.

As part of this network meta-analysis, we will address the following issues.

1. How does long-term efficacy compare between different pharmacological treatments for COPD?
2. Are there limitations in the current evidence base that may compromise the conclusions drawn by this network meta-analysis? If so, what are the implications for future research?

Search strategy: 

We identified randomised controlled trials (RCTs) in existing Cochrane reviews by searching the Cochrane Database of Systematic Reviews (CDSR). In addition, we ran a comprehensive citation search on the Cochrane Airways Group Register of trials (CAGR) and checked manufacturer websites and reference lists of other reviews. The most recent searches were conducted in September 2013.

Selection criteria: 

We included parallel-group RCTs of at least 6 months' duration recruiting people with COPD. Studies were included if they compared any of the following treatments versus any other: long-acting beta2-agonists (LABAs; formoterol, indacaterol, salmeterol); long-acting muscarinic antagonists (LAMAs; aclidinium, glycopyrronium, tiotropium); inhaled corticosteroids (ICSs; budesonide, fluticasone, mometasone); combination long-acting beta2-agonist (LABA) and inhaled corticosteroid (LABA/ICS) (formoterol/budesonide, formoterol/mometasone, salmeterol/fluticasone); and placebo.

Data collection and analysis: 

We conducted a network meta-analysis using Markov chain Monte Carlo methods for two efficacy outcomes: St George's Respiratory Questionnaire (SGRQ) total score and trough forced expiratory volume in one second (FEV1). We modelled the relative effectiveness of any two treatments as a function of each treatment relative to the reference treatment (placebo). We assumed that treatment effects were similar within treatment classes (LAMA, LABA, ICS, LABA/ICS). We present estimates of class effects, variability between treatments within each class and individual treatment effects compared with every other.

To justify the analyses, we assessed the trials for clinical and methodological transitivity across comparisons. We tested the robustness of our analyses by performing sensitivity analyses for lack of blinding and by considering six- and 12-month data separately.

Main results: 

We identified 71 RCTs randomly assigning 73,062 people with COPD to 184 treatment arms of interest. Trials were similar with regards to methodology, inclusion and exclusion criteria and key baseline characteristics. Participants were more often male, aged in their mid sixties, with FEV1 predicted normal between 40% and 50% and with substantial smoking histories (40+ pack-years). The risk of bias was generally low, although missing information made it hard to judge risk of selection bias and selective outcome reporting. Fixed effects were used for SGRQ analyses, and random effects for Trough FEV1 analyses, based on model fit statistics and deviance information criteria (DIC).

SGRQ
SGRQ data were available in 42 studies (n = 54,613). At six months, 39 pairwise comparisons were made between 18 treatments in 25 studies (n = 27,024). Combination LABA/ICS was the highest ranked intervention, with a mean improvement over placebo of -3.89 units at six months (95% credible interval (CrI) -4.70 to -2.97) and -3.60 at 12 months (95% CrI -4.63 to -2.34). LAMAs and LABAs were ranked second and third at six months, with mean differences of -2.63 (95% CrI -3.53 to -1.97) and -2.29 (95% CrI -3.18 to -1.53), respectively. Inhaled corticosteroids were ranked fourth (MD -2.00, 95% CrI -3.06 to -0.87). Class differences between LABA, LAMA and ICS were less prominent at 12 months. Indacaterol and aclidinium were ranked somewhat higher than other members of their classes, and formoterol 12 mcg, budesonide 400 mcg and formoterol/mometasone combination were ranked lower within their classes. There was considerable overlap in credible intervals and rankings for both classes and individual treatments.

Trough FEV1
Trough FEV1 data were available in 46 studies (n = 47,409). At six months, 41 pairwise comparisons were made between 20 treatments in 31 studies (n = 29,271). As for SGRQ, combination LABA/ICS was the highest ranked class, with a mean improvement over placebo of 133.3 mL at six months (95% CrI 100.6 to 164.0) and slightly less at 12 months (mean difference (MD) 100, 95% CrI 55.5 to 140.1). LAMAs (MD 103.5, 95% CrI 81.8 to 124.9) and LABAs (MD 99.4, 95% CrI 72.0 to 127.8) showed roughly equivalent results at six months, and ICSs were the fourth ranked class (MD 65.4, 95% CrI 33.1 to 96.9). As with SGRQ, initial differences between classes were not so prominent at 12 months. Indacaterol and salmeterol/fluticasone were ranked slightly better than others in their class, and formoterol 12, aclidinium, budesonide and formoterol/budesonide combination were ranked lower within their classes. All credible intervals for individual rankings were wide.

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