title: Conceptual structure of the Taiwan Chinese version of the EORTC QLQ-C30.
abstract: OBJECTIVE
  This study aimed to evaluate the conceptual structure of the European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire 30 (EORTC QLQ-C30) by analyzing data collected from patients with major cancers in Taiwan. The conceptual structure underlying QLQ-C30, including higher-order factors, was explored by structural equation modeling (SEM).
  
  
  METHODS
  The Taiwan Chinese version of the EORTC QLQ-C30 was used as the measuring instrument. Higher-order models, including mental health/physical health, mental function/physical burden, symptom burden/function, single latent health-related quality of life, formative symptom burden/function, and formative health-related quality of life, were tested.
  
  
  RESULTS
  Study subjects included 283 patients with breast, lung, and nasopharyngeal cancers. The original QLQ-C30 multi-factorial structure demonstrated poor composite reliability of the cognitive function subscale. The formative symptom/burden model was favored by model fit indices, further supporting causal-indicator duality, but was compromised by unexpected associations between symptomatic subscales and latent factors. The formative health-related quality of life was proposed with a single second-order latent factor where symptomatic subscales remained formative. Two additional symptom measures from the formal cognitive function subscale with the formative health-related quality-of-life model were proposed as the alterative conceptual structure for the Taiwan Chinese QLQ-C30.
  
  
  CONCLUSIONS
  Results of the current study represent the complete SEM approach for the EORTC QLQ-C30. The formative health-related quality-of-life model with elimination of cognitive function enhances the conceptual structure of the Taiwan Chinese version with parsimonious fit and interpretability.
authors.affiliation: Cathay General Hospital SiJhih, New Taipei City, Taiwan.
authors.forename: Chi-Cheng
authors.initials: CC
authors.lastname: Huang
authors.forename: Shih-Hsin
authors.initials: SH
authors.lastname: Tu
authors.forename: Heng-Hui
authors.initials: HH
authors.lastname: Lien
authors.forename: Ching-Shui
authors.initials: CS
authors.lastname: Huang
authors.forename: Pa-Chun
authors.initials: PC
authors.lastname: Wang
authors.forename: Wei-Chu
authors.initials: WC
authors.lastname: Chie
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D001943:Breast Neoplasms / Q000523:psychology; D003071:Cognition / Q000502:physiology; D005260:Female; D006304:Health Status; D006801:Humans; D008175:Lung Neoplasms / Q000523:psychology; D008297:Male; D008603:Mental Health; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000523:psychology; D011788:Quality of Life; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D013624:Taiwan; D055815:Young Adult