title: Identification of chronic rhinosinusitis phenotypes using cluster analysis.
abstract: BACKGROUND
  Current clinical classifications of chronic rhinosinusitis (CRS) have been largely defined based upon preconceived notions of factors thought to be important, such as polyp or eosinophil status. Unfortunately, these classification systems have little correlation with symptom severity or treatment outcomes. Unsupervised clustering can be used to identify phenotypic subgroups of CRS patients, describe clinical differences in these clusters and define simple algorithms for classification.
  
  
  METHODS
  A multi-institutional, prospective study of 382 patients with CRS who had failed initial medical therapy completed the Sino-Nasal Outcome Test (SNOT-22), Rhinosinusitis Disability Index (RSDI), Medical Outcomes Study Short Form-12 (SF-12), Pittsburgh Sleep Quality Index (PSQI), and Patient Health Questionnaire (PHQ-2). Objective measures of CRS severity included Brief Smell Identification Test (B-SIT), CT, and endoscopy scoring. All variables were reduced and unsupervised hierarchical clustering was performed. After clusters were defined, variations in medication usage were analyzed. Discriminant analysis was performed to develop a simplified, clinically useful algorithm for clustering.
  
  
  RESULTS
  Clustering was largely determined by age, severity of patient reported outcome measures, depression, and fibromyalgia. CT and endoscopy varied somewhat among clusters. Traditional clinical measures, including polyp/atopic status, prior surgery, B-SIT and asthma, did not vary among clusters. A simplified algorithm based upon productivity loss, SNOT-22 score, and age predicted clustering with 89% accuracy. Medication usage among clusters did vary significantly.
  
  
  CONCLUSIONS
  A simplified algorithm based upon hierarchical clustering is able to classify CRS patients and predict medication usage. Further studies are warranted to determine if such clustering predicts treatment outcomes.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston, SC.
authors.forename: Zachary M
authors.initials: ZM
authors.lastname: Soler
authors.affiliation: Department of Public Health Sciences, Medical University of South Carolina, Charleston, SC.
authors.forename: J Madison
authors.initials: JM
authors.lastname: Hyer
authors.affiliation: Department of Public Health Sciences, Medical University of South Carolina, Charleston, SC.
authors.forename: Viswanathan
authors.initials: V
authors.lastname: Ramakrishnan
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Oregon Health Sciences University, Portland, OR.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Smith
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Oregon Health Sciences University, Portland, OR.
authors.forename: Jess
authors.initials: J
authors.lastname: Mace
authors.affiliation: Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Luke
authors.initials: L
authors.lastname: Rudmik
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston, SC.
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Schlosser
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D016000:Cluster Analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011446:Prospective Studies; D011788:Quality of Life; D012220:Rhinitis / Q000145:classification / Q000175:diagnosis*; D018434:Sickness Impact Profile; D012852:Sinusitis / Q000145:classification / Q000175:diagnosis*; D011795:Surveys and Questionnaires
keywords: cluster analysis; phenotype; quality of life; sinusitis; staging