Clinical response to long-acting bronchodilators (LABD) therapy is difficult to predict and is often non-linear, observes a recent study. The study by a team of researchers from various medical centres and hospitals across Europe showed that individual responses to 4 weeks of  aclidinium bromide/formoterol fumarate (AB/FF) treatment in COPD were found to be widely different and the degree of change differs across domains of lung function, exercise capacity and physical activity, suggesting that it is important to look at multiple outcomes simultaneously when evaluating outcomes of LABD therapy. The research analysed the lung function, exercise capacity and physical activity in 250 patients with COPD.  The findings indicated six clusters with differential outcomes, including clusters 1 and 2 with significant improvements in lung function, clusters 1 and 3 with significant improvements in CWRT time, and clusters 2, 3 and 6 had significant improvements in physical activity compared to the remaining AB/FF-treated patients.