1. Department of Organization and Economics of Pharmacy, Faculty of Pharmacy, Medical University of Sofia, Sofia, Bulgaria;
2. Department of General Practice, Groningen Research Institute for Asthma and COPD (GRIAC), University Medical Center Groningen, University of Groningen, Groningen, The Netherlands;
3. Unit of Pharmacotherapy, Epidemiology and – Economics, Department of Pharmacy, University of Groningen, Groningen, The Netherlands;
4. Institute of Science in Healthy Aging & healthcaRE (SHARE), University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands;
5. Department of Epidemiology, University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands;
6. Department of General Practice, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands;
7. Department of Propaedeutic of Internal Diseases, UMHAT ‘Alexandrovska’, Medical University, Sofia, Bulgaria