title: Differences in classification of COPD group using COPD assessment test (CAT) or modified Medical Research Council (mMRC) dyspnea scores: a cross-sectional analyses.
abstract: BACKGROUND
  The GOLD 2011 document proposed a new classification system for COPD combining symptom assessment by COPD assessment test (CAT) or modified Medical Research Council (mMRC) dyspnea scores, and exacerbation risk. We postulated that classification of COPD would be different by the symptom scale; CAT vs mMRC.
  
  
  METHODS
  Outpatients with COPD were enrolled from January to June in 2012. The patients were categorized into A, B, C, and D according to the GOLD 2011; patients were categorized twice with mMRC and CAT score for symptom assessment, respectively. Additionally, correlations between mMRC scores and each item of CAT scores were analyzed.
  
  
  RESULTS
  Classification of 257 patients using the CAT score vs mMRC scale was as follows. By using CAT score, 60 (23.3%) patients were assigned to group A, 55 (21.4%) to group B, 21 (8.2%) to group C, and 121 (47.1%) to group D. On the basis of the mMRC scale, 97 (37.7%) patients were assigned to group A, 18 (7.0%) to group B, 62 (24.1%) to group C, and 80 (31.1%) to group D. The kappa of agreement for the GOLD groups classified by CAT and mMRC was 0.510. The mMRC score displayed a wide range of correlation with each CAT item (r = 0.290 for sputum item to r = 0.731 for dyspnea item, p < 0.001).
  
  
  CONCLUSIONS
  The classification of COPD produced by the mMRC or CAT score was not identical. Care should be taken when stratifying COPD patients with one symptom scale versus another according to the GOLD 2011 document.
authors.affiliation: Division of Pulmonology, Department of Internal Medicine, Chonnam National University Hospital, 42 Jebong-ro, Donggu 501-757, Gwangju, South Korea.
authors.forename: Sunmin
authors.initials: S
authors.lastname: Kim
authors.forename: Jisun
authors.initials: J
authors.lastname: Oh
authors.forename: Yu-Il
authors.initials: YI
authors.lastname: Kim
authors.forename: Hee-Jung
authors.initials: HJ
authors.lastname: Ban
authors.forename: Yong-Soo
authors.initials: YS
authors.lastname: Kwon
authors.forename: In-Jae
authors.initials: IJ
authors.lastname: Oh
authors.forename: Kyu-Sik
authors.initials: KS
authors.lastname: Kim
authors.forename: Young-Chul
authors.initials: YC
authors.lastname: Kim
authors.forename: Sung-Chul
authors.initials: SC
authors.lastname: Lim
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D004417:Dyspnea / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000145:classification* / Q000150:complications / Q000175:diagnosis*; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D063189:Symptom Assessment / Q000379:methods*; D014797:Vital Capacity / Q000502:physiology