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Abstract and Introduction
Abstract
Background: Statins are lipid-lowering agents that also exhibit pleiotropic effects in decreasing oxidative stress and inflammation. There have been several published studies reporting the use of statins in the treatment of asthma patients, but their results are not consistent. The aim of this study is to determine whether statins are beneficial for asthma administration, and explore the potential covariables that may affect their clinical effectiveness.
Methods: A systematic literature search was performed in PubMed, Embase and Cochrane Center Register of Controlled Trials from inception to September 2012. Randomized controlled trials (RCT), retrospective studies and controlled clinical trials which reported the use of statins in the treatment of asthma patients were eligible. Quality evaluation was conducted for RCT using Jadad criteria.
Results: A total of 18 articles were included. In our study, we found no conclusive evidence to demonstrate that statins could enhance the lung function in asthmatics, although, they may reduce airway inflammation. Additionally, the results were not consistent across studies with respect to symptoms, quality of life, maintenance medication, asthma hospitalization/emergency department (ED) visits.
Conclusions: Statins may reduce airway inflammation in asthmatics, without having a significant effect on lung function. Further large sample and multicenter clinical trials are needed to confirm this and to see if there are more responsive phenotypes of asthma.
Introduction
Chronic airway inflammation plays a major role in the pathophysiology of asthma, and is also associated with airway hyperresponsiveness. Glucocorticoids,leukotriene modifiers, and anti-IgE antibody are the main anti-inflammatory medications to keep asthma under clinical control chiefly through their anti-inflammatory effects. However, specific subpopulations of individuals including smokers, obese asthmatics and non-Th2-high asthmatics respond poorly to the above medications.
Statins,inhibitors of hydroxymethylglutaryl coenzyme A (HMG-A) reductase,can inhibit the mevalonate pathway and the synthesis of downstream intermediates including farnesylpyrophosphate (FPP) and geranylgeranylpyrophosphate (GGPP), which post-translationally modify small guanosine triphosphatases (GTPases). GTPases may play a role in the pathophysiology of asthma, because they could enhance airway smooth muscle contraction and proliferation, and increase airway hyperresponsiveness. Studies have demonstrated that statins reduce the total inflammatory cell infiltrate and eosinophilia in bronchoalveolar lavage fluid in an animal model of asthma and inhibit the airway smooth muscle proliferation and contraction in vitro.
In 2009, a retrospective study by Stanek et al. showed that statin therapy was independently associated with a significant 33% relative risk reduction for recurrent asthma-related hospitalization/emergency department (ED) events. Recently, several studies have been performed in asthmatics to investigate the clinical effectiveness of statins in asthma. Some studies suggested that short-term treatment with statins could increase lung function, enhance the anti-inflammatory effect of inhaled corticosteroids (ICS), and improve the Asthma Control Questionnaire (ACQ) and Asthma Quality of Life Questionnaire (AQLQ). However, other studies failed to replicate these results. Therefore, we performed a systematic review to see whether asthmatic patients could benefit clinically from statins, and explore potential factors that may affect their clinical effectiveness.
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