1. Bamdad Respiratory and Sleep Research Center, Pulmonary and Sleep Ward, Department of Internal Medicine, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
2. Department of Internal Medicine, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
3. Department of Epidemiology and Biostatistics, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran
4. Respiratory Division, McGill University Health Centre, Montreal, Quebec, Canada