The investigators will compare the circulating fibrocyte proportion in asthmatic patients with obstructive sleep apnea (OSA) and not with OSA In addition, the investigators will compare the expression of epidermal growth factor receptor (EGFR), endothelin A receptor (ETAR) and connective tissue growth factor (CTGF) The association of those factors and annual decline of forced expiratory volume in 1 second (FEV1) will be performed