<qa>  What is the name of the study that will compare patients with and without bronchiectA single center case-control study with 100 COPD patients will be organized to compare patients with and without bronchiectasis with regard to the presence of Aspergillus in sputum samples, Aspergillus sensitization and vitamin D. Induced sputum samples will be optimized for culture, Aspergillus galatomannan analysis and RT-PCR. 