title: Development and validation of the coronary heart disease scale under the system of quality of life instruments for chronic diseases QLICD-CHD: combinations of classical test theory and Generalizability Theory.
abstract: BACKGROUND
  Quality of life (QOL) for patients with coronary heart disease (CHD) is now concerned worldwide with the specific instruments being seldom and no one developed by the modular approach.
  
  
  OBJECTIVE
  This paper is aimed to develop the CHD scale of the system of Quality of Life Instruments for Chronic Diseases (QLICD-CHD) by the modular approach and validate it by both classical test theory and Generalizability Theory.
  
  
  METHODS
  The QLICD-CHD was developed based on programmed decision procedures with multiple nominal and focus group discussions, in-depth interview, pre-testing and quantitative statistical procedures. 146 inpatients with CHD were used to provide the data measuring QOL three times before and after treatments. The psychometric properties of the scale were evaluated with respect to validity, reliability and responsiveness employing correlation analysis, factor analyses, multi-trait scaling analysis, t-tests and also G studies and D studies of Genralizability Theory analysis.
  
  
  RESULTS
  Multi-trait scaling analysis, correlation and factor analyses confirmed good construct validity and criterion-related validity when using SF-36 as a criterion. The internal consistency α and test-retest reliability coefficients (Pearson r and Intra-class correlations ICC) for the overall instrument and all domains were higher than 0.70 and 0.80 respectively; The overall and all domains except for social domain had statistically significant changes after treatments with moderate effect size SRM (standardized response mea) ranging from 0.32 to 0.67. G-coefficients and index of dependability (Ф coefficients) confirmed the reliability of the scale further with more exact variance components.
  
  
  CONCLUSIONS
  The QLICD-CHD has good validity, reliability, and moderate responsiveness and some highlights, and can be used as the quality of life instrument for patients with CHD. However, in order to obtain better reliability, the numbers of items for social domain should be increased or the items' quality, not quantity, should be improved.
authors.affiliation: School of Humanities and Management, Guangdong Medical College, Dongguan 523808, China. wanchh@hotmail.com.
authors.forename: Chonghua
authors.initials: C
authors.lastname: Wan
authors.forename: Hezhan
authors.initials: H
authors.lastname: Li
authors.forename: Xuejin
authors.initials: X
authors.lastname: Fan
authors.forename: Ruixue
authors.initials: R
authors.lastname: Yang
authors.forename: Jiahua
authors.initials: J
authors.lastname: Pan
authors.forename: Wenru
authors.initials: W
authors.lastname: Chen
authors.forename: Rong
authors.initials: R
authors.lastname: Zhao
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003327:Coronary Disease / Q000523:psychology*; D005163:Factor Analysis, Statistical; D005260:Female; D017144:Focus Groups; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D011594:Psychometrics; D011788:Quality of Life / Q000523:psychology; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D055815:Young Adult