David JW Evans, Kayleigh M Kew, Debbie E Anderson, Anne C Boyter

Long-acting muscarinic antagonists (LAMA), a class of drugs with proven effectiveness in chronic obstructive pulmonary disease (COPD), are being considered as an add-on option for adults with asthma whose condition is uncontrolled on inhaled corticosteroids (ICS). It is important to assess the safety and efficacy of LAMA add-on as an alternative to the prolonged use of higher doses of ICS, which are known to cause undesirable side effects in some people. To compare the effects of adding a LAMA to any dose of ICS versus increasing the dose of ICS, for uncontrolled asthma in adults. We searched the Cochrane Airways Group Specialised Register (CAGR) from its inception in 1995 to April 2015, imposing no restriction on language of publication. We also handsearched trial registries, reference lists of primary studies and existing reviews, as well as manufacturers' websites. We looked for parallel or cross-over randomised controlled trials lasting at least 12 weeks, in which adults whose asthma was not well controlled on ICS alone were randomised to treatment with LAMA add-on to ICS or with an increased dose of ICS. Trials were excluded if patients were taking long-acting beta2-agonists during the study period. Two review authors independently screened the searches and extracted data from studies meeting all the inclusion criteria. We used Covidence to manage duplicate screening, data extraction and risk of bias judgements, and to form a consensus where discrepancies arose. We used standard methods expected by The Cochrane Collaboration.The pre-specified primary outcomes were exacerbations requiring a course of oral corticosteroids (OCS), effects on quality of life and serious adverse events. One cross-over randomised controlled trial met the inclusion criteria. The trial was performed in 210 patients with moderate to severe asthma and compared the use of the LAMA tiotropium bromide with double dose beclomethasone (an ICS) using a cross-over design and 14-week treatment periods.Compared with people taking a double dose of ICS, fewer people taking a LAMA add-on had an exacerbation requiring treatment with OCS (odds ratio (OR) 0.57, 95% confidence interval (CI) 0.22 to 1.43) or an exacerbation resulting in emergency department admission (OR 0.49, 95% CI 0.09 to 2.77), but the confidence intervals for both outcomes did not exclude the possibility that double dose ICS was more effective. Serious adverse events and exacerbations requiring hospitalisation occurred in similarly low numbers of people taking each treatment, but confidence intervals were too wide to suggest that the two treatment options were equivalent.Asthma-related quality of life was similar in both treatment groups (mean difference (MD) in change from baseline 0.10, 95% CI - 0.07 to 0.27). Those taking LAMA add-on scored slightly better on a scale measuring asthma control than those increasing their ICS dose (MD in change from baseline - 0.18, 95% CI - 0.34 to - 0.02), although the difference was clinically small. Evidence was deemed low quality for both quality of life and asthma control.There was moderate-quality evidence that participants' trough forced expiratory volume in one second (FEV1) was 100 mL better when taking LAMA add-on than with increased ICS dose (MD in change from baseline 0.10, 95% CI 0.03 to 0.17). Only one randomised trial was found, comparing tiotropium add-on to increased dose beclomethasone. Differences between the treatments were too small or imprecise to understand whether adding a LAMA to ICS is safer or more effective than increasing the dose of ICS, and there is a possibility of carry-over effects due to the study's cross-over design. LAMA add-on may lead to more improvement in lung function (FEV1) than an increased dose of ICS.The results of this review, alongside pending results from related reviews assessing the use of LAMA against other treatments, will help to define the role of these drugs in asthma management, and this review should be updated as results from future trials emerge. Studies assessing the role of LAMA add-on should be longer and include a double-ICS treatment arm so that the results can be interpreted in the context of the guideline-recommended treatment options that are available to physicians.