Doxycycline may be more clinically effective in type 2 chronic rhinosinusitis nasal polyp comorbid with asthma.

Objective: Chronic rhinosinusitis with nasal polyp (CRSwNP) is one of the major phenotypes of chronic rhinosinusitis (CRS) with a high symptom burden. Doxycycline can be used as add-on therapy in CRSwNP. We aimed to evaluate short-term efficacy of oral doxycycline on visual analog scale (VAS) and SNOT-22 (Sino-nasal outcome test) score for CRSwNP.
Methods: Visual analog score (VAS) for nasal symptoms and total SNOT-22 scores of 28 patients who applied with the diagnosis of CRSwNP and received 100 mg doxycycline for 21 days were analyzed in this retrospective cohort study. Doxycycline efficacy was also evaluated in subgroups determined according to asthma, presence of atopy, total IgE and eosinophil levels.
Results: After 21-day doxycycline treatment, there was a significant improvement in VAS score for post-nasal drip, nasal discharge, nasal congestion, and sneeze, and total SNOT-22 score ( p  = 0.001, p  < 0.001, p  < 0.001, p  < 0.001, p  < 0.001, respectively). No significant improvement was observed in VAS score for the loss of smell ( p  = 0.18). In the asthmatic subgroup, there were significant improvements in all VAS scores and total SNOT-22 score after doxycycline. In the non-asthmatic subgroup, there was no significant change in any of the VAS scores, but total SNOT-22 score was significantly improved (42 [21-78] vs. 18 [9-33]; p  = 0.043). Improvement in VAS score for loss of smell is significant in only some subgroups like asthmatic patients, non-atopic patients, and patients with eosinophil >300 cell/µL.
Conclusions: Doxycycline can be considered as an add-on treatment for symptom control in patients especially with CRSwNP comorbid with asthma.