Measurement of CRS severity and course

CRS severity was assessed by the Lund-Mackay score (LMS) [18], which was based on coronal CT scanning of patients in the bilateral maxillary sinus, anterior ethmoid sinus, posterior ethmoid sinus, frontal sinus and sphenoid sinus. The complete lucency, partial opacity and complete opacity of fluid accumulated from the sinus was scored as 0, 1, and 2 respectively. Remarkably, the ostiomeatal complex was scored as either 0 or 2 for not being obstructed or obstructed. Therefore, LMS for the right or left sinus ranged from 0~12 with a total score 0~24 for both sides. The CRS course was counted during the collecting history as the number of months from the complaint of onset until visiting the hospital.