Unsupervised cluster analysis of chronic rhinosinusitis with nasal polyp using routinely available clinical markers and its implication in treatment outcomes

Background Chronic rhinosinusitis with nasal polyps (CRSwNP) is a multidimensional disease. In this study, we performed an unsupervised cluster analysis of CRSwNP using routinely available clinical markers. Methods We conducted a retrospective review of patients treated with endoscopic sinus surgery due to medically intractable bilateral CRSwNP from 2009 to 2017. Unsupervised cluster analysis was performed using a patient's clinical features, including age, peripheral blood eosinophil, tissue eosinophilia, Lund‐Mackay computed tomography (CT) scores, ratio of the CT scores for the ethmoid sinus and maxillary sinus (E/M ratio), and comorbid asthma. Tree analysis was performed to develop a clustering algorithm. Kaplan‐Meier survival analysis was performed to determine the revision surgery–free probability corresponding to each cluster. Results Data were available on 375 patients. Patients were categorized into 6 clusters comprising 2 asthmatic clusters and 4 non‐asthmatic clusters. The labels for the 2 asthmatic clusters were: asthmatic non‐eosinophilic polyp (cluster A1) and asthmatic eosinophilic polyp (cluster A2). The labels for the 4 non‐asthmatic clusters were: non‐eosinophilic polyp with older age (cluster NA1); non‐eosinophilic pol'yp with younger age (cluster NA2); eosinophilic polyp with lower E/M ratio (cluster NA3); and eosinophilic polyp with higher E/M ratio (cluster NA4). The 4‐year revision‐free rates were 100% (cluster NA1), 80.3% (NA2), 98.0% (NA3), 66.7% (NA4), 100% (A1), and 66.7% (A2). The clusters showed statistically significant differences in terms of 4‐year revision‐free rates (log‐rank p < 0.05). Conclusion Cluster analysis identified 2 asthmatic clusters and 4 non‐asthmatic clusters in CRSwNP. Each cluster corresponded to a different clinical outcome.