Background to the review
COPD is a disease of the lungs that causes airways to narrow. As a result, people with COPD experience symptoms of breathlessness, cough and mucus buildup, which worsen over time. Cigarette smoking is the most common cause of COPD, and it is the fourth or fifth most common cause of death worldwide.
Inhaled salmeterol and formoterol, known as long-acting beta2-agonists (LABAs), are widely used to manage the symptoms of COPD, so it is important to understand their benefits and side effects. They are often introduced when inhaled treatments for quick relief from symptoms (e.g. salbutamol) are no longer helpful. LABAs are designed to be taken twice a day to control symptoms and reduce the likelihood of flare-ups.
What did we find?
Twenty-six studies (including 14,939 people with moderate to severe symptoms of COPD) compared twice-daily salmeterol or formoterol with a dummy inhaler. The evidence gathered for this review is current up to June 2013. Results within studies were described most often after six months of treatment, but some were reported at three months and others after as long as three years. More men than women took part, and they had moderate to severe symptoms when they began treatment.
People who took LABA inhalers showed greater improvement on quality of life scales than those taking dummy inhalers, and they had fewer serious flare-ups that resulted in a hospital stay (18 fewer per 1000). They also had better lung function than people who had taken placebo. LABA inhalers did not reduce the number of people who died, and no significant difference was noted in the number who had serious adverse events while taking the medication.
These studies were most often sponsored by drug companies and were generally well designed. People in the studies did not know which treatment they were getting, and neither did the people doing the research. Several studies did not describe flare-ups, hospital stays or lung volume, so there is a chance that evidence obtained in future studies would change the strength of what has been concluded. Additionally, quite a lot of variation was noted between studies in the effects of LABA inhalers on quality of life, serious side effects and lung function. This may be explained in part by variation in study methods regarding what medications people could continue to take.