• Usman Maqsood, Terence N Ho, Karen Palmer, Fiona Jr Eccles, Mohammed Munavvar, Ran Wang, Iain Crossingham, and David Jw Evans.
• Department of Respiratory Medicine, Sandwell and West Birmingham Hospitals NHS Trust, Birmingham, UK.
• Cochrane Db Syst Rev. 2019 Mar 6; 3 (3): CD012930CD012930.

BackgroundChronic obstructive pulmonary disease (COPD) is a respiratory condition causing accumulation of mucus in the airways, cough, and breathlessness; the disease is progressive and is the fourth most common cause of death worldwide. Current treatment strategies for COPD are multi-modal and aim to reduce morbidity and mortality and increase patients' quality of life by slowing disease progression and preventing exacerbations. Fixed-dose combinations (FDCs) of a long-acting beta2-agonist (LABA) plus a long-acting muscarinic antagonist (LAMA) delivered via a single inhaler are approved by regulatory authorities in the USA, Europe, and Japan for the treatment of COPD. Several LABA/LAMA FDCs are available and recent meta-analyses have clarified their utility versus their mono-components in COPD. Evaluation of the efficacy and safety of once-daily LABA/LAMA FDCs versus placebo will facilitate the comparison of different FDCs in future network meta-analyses.ObjectivesWe assessed the evidence for once-daily LABA/LAMA combinations (delivered in a single inhaler) versus placebo on clinically meaningful outcomes in patients with stable COPD.Search MethodsWe identified trials from Cochrane Airways' Specialised Register (CASR) and also conducted a search of the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization International Clinical Trials Registry Platform (apps.who.int/trialsearch). We searched CASR and trial registries from their inception to 3 December 2018; we imposed no restriction on language of publication.Selection CriteriaWe included parallel-group and cross-over randomised controlled trials (RCTs) comparing once-daily LABA/LAMA FDC versus placebo. We included studies reported as full-text, those published as abstract only, and unpublished data. We excluded very short-term trials with a duration of less than 3 weeks. We included adults (≥ 40 years old) with a diagnosis of stable COPD. We included studies that allowed participants to continue using their ICS during the trial as long as the ICS was not part of the randomised treatment.Data Collection And AnalysisTwo review authors independently screened the search results to determine included studies, extracted data on prespecified outcomes of interest, and assessed the risk of bias of included studies; we resolved disagreements by discussion with a third review author. Where possible, we used a random-effects model to meta-analyse extracted data. We rated all outcomes using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) system and presented results in 'Summary of findings' tables.Main ResultsWe identified and included 22 RCTs randomly assigning 8641 people with COPD to either once-daily LABA/LAMA FDC (6252 participants) or placebo (3819 participants); nine studies had a cross-over design. Studies had a duration of between three and 52 weeks (median 12 weeks). The mean age of participants across the included studies ranged from 59 to 65 years and in 21 of 22 studies, participants had GOLD stage II or III COPD. Concomitant inhaled corticosteroid (ICS) use was permitted in all of the included studies (where stated); across the included studies, between 28% to 58% of participants were using ICS at baseline. Six studies evaluated the once-daily combination of IND/GLY (110/50 μg), seven studies evaluated TIO/OLO (2.5/5 or 5/5 μg), eight studies evaluated UMEC/VI (62.5/5, 125/25 or 500/25 μg) and one study evaluated ACD/FOR (200/6, 200/12 or 200/18 μg); all LABA/LAMA combinations were compared with placebo.The risk of bias was generally considered to be low or unknown (insufficient detail provided), with only one study per domain considered to have a high risk of bias except for the domain 'other bias' which was determined to be at high risk of bias in four studies (in three studies, disease severity was greater at baseline in participants receiving LABA/LAMA compared with participants receiving placebo, which would be expected to shift the treatment effect in favour of placebo).Compared to the placebo, the pooled results for the primary outcomes for the once-daily LABA/LAMA arm were as follows: all-cause mortality, OR 1.88 (95% CI 0.81 to 4.36, low-certainty evidence); all-cause serious adverse events (SAEs), OR 1.06 (95% CI 0.88 to 1.28, high-certainty evidence); acute exacerbations of COPD (AECOPD), OR 0.53 (95% CI 0.36 to 0.78, moderate-certainty evidence); adjusted St George's Respiratory Questionnaire (SGRQ) score, MD -4.08 (95% CI -4.80 to -3.36, high-certainty evidence); proportion of SGRQ responders, OR 1.75 (95% CI 1.54 to 1.99). Compared with placebo, the pooled results for the secondary outcomes for the once-daily LABA/LAMA arm were as follows: adjusted trough forced expiratory volume in one second (FEV1), MD 0.20 L (95% CI 0.19 to 0.21, moderate-certainty evidence); adjusted peak FEV1, MD 0.31 L (95% CI 0.29 to 0.32, moderate-certainty evidence); and all-cause AEs, OR 0.95 (95% CI 0.86 to 1.04; high-certainty evidence). No studies reported data for the 6-minute walk test. The results were generally consistent across subgroups for different LABA/LAMA combinations and doses.Authors' ConclusionsCompared with placebo, once-daily LABA/LAMA (either IND/GLY, UMEC/VI or TIO/OLO) via a combination inhaler is associated with a clinically significant improvement in lung function and health-related quality of life in patients with mild-to-moderate COPD; UMEC/VI appears to reduce the rate of exacerbations in this population. These conclusions are supported by moderate or high certainty evidence based on studies with an observation period of up to one year.

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