The Cornell and Stanford universities' statistical analysis of 22 trials with 15,276 participants found that common bronchodilators known as anticholinergics reduced severe respiratory events by 33 percent and respiratory-related deaths by 73 percent, compared with a placebo.

However, the same meta-analysis found that regularly inhaled beta-agonists increased the risk of respiratory death more than twofold, compared with a placebo. Yet only five percent of all prescriptions for COPD are anticholinergics, with beta-agonists dominating what doctors prescribe, the researchers report.

"When patients used the anticholinergics, they experienced fewer severe exacerbations requiring hospitalisations and fewer respiratory deaths than those taking only a placebo," said Edwin Salpeter, the J.G. White Distinguished Professor of Physical Sciences Emeritus at Cornell, who led the statistical analysis in the study. "With the beta-agonists, it's the other way around, where the number of respiratory deaths increased when compared with those who took only the placebo."

A recent meta-analysis by Salpeter also revealed that beta-agonist inhalers increased both hospitalisations and deaths in asthma sufferers of all ages. Previous studies have shown that patients with COPD build up tolerance to beta-agonists' bronchodilator and bronchoprotective effects after regular treatment compared with the first dose.

While beta-agonists may reduce symptoms through bronchodilation, the researchers believe they also promote bronchial inflammation and sensitivity by reducing bronchial protection without any warning of increased symptoms, which can then lead to a life-threatening response.

MEDICA.de; Source: Cornell University