title: Quantifying traditional Chinese medicine patterns using modern test theory: an example of functional constipation.
abstract: BACKGROUND
  The study aimed to validate a scale to assess the severity of "Yin deficiency, intestine heat" pattern of functional constipation based on the modern test theory.
  
  
  METHODS
  Pooled longitudinal data of 237 patients with "Yin deficiency, intestine heat" pattern of constipation from a prospective cohort study were used to validate the scale. Exploratory factor analysis was used to examine the common factors of items. A multidimensional item response model was used to assess the scale with the presence of multidimensionality.
  
  
  RESULTS
  The Cronbach's alpha ranged from 0.79 to 0.89, and the split-half reliability ranged from 0.67 to 0.79 at different measurements. Exploratory factor analysis identified two common factors, and all items had cross factor loadings. Bidimensional model had better goodness of fit than the unidimensional model. Multidimensional item response model showed that the all items had moderate to high discrimination parameters. Parameters indicated that the first latent trait signified intestine heat, while the second trait characterized Yin deficiency. Information function showed that items demonstrated highest discrimination power among patients with moderate to high level of disease severity.
  
  
  CONCLUSIONS
  Multidimensional item response theory provides a useful and rational approach in validating scales for assessing the severity of patterns in traditional Chinese medicine.
authors.affiliation: Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China.|Hunan Key Laboratory of Skin Cancer and Psoriasis, Changsha, Hunan, People's Republic of China.|Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, Hunan, People's Republic of China.
authors.forename: Minxue
authors.initials: M
authors.lastname: Shen
authors.affiliation: The Second Affiliated Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.
authors.forename: Yuanwu
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, Hunan, People's Republic of China. xysm2011@yeah.com.
authors.forename: Ming
authors.initials: M
authors.lastname: Hu
authors.affiliation: Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, Hunan, People's Republic of China. linyongxu@gmail.com.
authors.forename: Linyong
authors.initials: L
authors.lastname: Xu
mesh_terms: D000328:Adult; D000368:Aged; D003248:Constipation / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008516:Medicine, Chinese Traditional; D008875:Middle Aged; D011446:Prospective Studies; D016710:Yin Deficiency / Q000175:diagnosis*; D055815:Young Adult
keywords: Functional constipation; Multidimensional item response theory; Scale validation; Traditional Chinese medicine