BCQ+: a body constitution questionnaire to assess Yang-Xu. Part II: Evaluation of reliability and validity.

INTRODUCTION: Integrated medicine has become an important issue in this century. In order to bridge the gap between traditional Chinese medicine (TCM) and modern medicine, we have established a first final version of a Yang-Xu constitution questionnaire, the BCQ+, in a previous study. The objective of the present investigation is to assess the reliability and validity of the BCQ+. PARTICIPANTS AND METHODS: A total of 1,310 eligible participants, aged between 20-60, no disease onset in the past month, who received health examination in teaching hospitals were recruited. The BCQ+ was developed and psychometrically evaluated to ascertain and validate the factor structure of the BCQ+. Furthermore, the reliability and validity of the BCQ+ were examined. RESULTS: 19 items from the BCQ+ were developed. Exploratory factor analysis identified 5 primary domains that represent the Yang-Xu constitution and correspond to the diminishing energy levels of 5 different body areas: head, chest, limbs, abdominal cavity, and body surface. Cronbach's alpha ranged between 0.55-0.88 and the intraclass correlation coefficients were >0.7 for most of the 19 questions. The diagnoses of Yang-Xu by the BCQ+ and an experienced TCM doctor were consistent. Systolic blood pressure (SBP) was used as an indicator of concurrent validity of the BCQ+, and it was found that higher Yang-Xu scores were associated with a lower SBP. CONCLUSIONS: Five domains with 19 items in the BCQ+ were developed. The BCQ+ is a valid and potentially useful tool for evaluating the Yang-Xu constitution in clinical practice and research.