title: Development and evaluation of a questionnaire for measuring suboptimal health status in urban Chinese.
abstract: BACKGROUND
  Suboptimal health status (SHS) is characterized by ambiguous health complaints, general weakness, and lack of vitality, and has become a new public health challenge in China. It is believed to be a subclinical, reversible stage of chronic disease. Studies of intervention and prognosis for SHS are expected to become increasingly important. Consequently, a reliable and valid instrument to assess SHS is essential. We developed and evaluated a questionnaire for measuring SHS in urban Chinese.
  
  
  METHODS
  Focus group discussions and a literature review provided the basis for the development of the questionnaire. Questionnaire validity and reliability were evaluated in a small pilot study and in a larger cross-sectional study of 3000 individuals. Analyses included tests for reliability and internal consistency, exploratory and confirmatory factor analysis, and tests for discriminative ability and convergent validity.
  
  
  RESULTS
  The final questionnaire included 25 items on SHS (SHSQ-25), and encompassed 5 subscales: fatigue, the cardiovascular system, the digestive tract, the immune system, and mental status. Overall, 2799 of 3000 participants completed the questionnaire (93.3%). Test-retest reliability coefficients of individual items ranged from 0.89 to 0.98. Item-subscale correlations ranged from 0.51 to 0.72, and Cronbach's alpha was 0.70 or higher for all subscales. Factor analysis established 5 distinct domains, as conceptualized in our model. One-way ANOVA showed statistically significant differences in scale scores between 3 occupation groups; these included total scores and subscores (P<0.01). The correlation between the SHS scores and experienced stress was statistically significant (r=0.57, P<0.001).
  
  
  CONCLUSIONS
  The SHSQ-25 is a reliable and valid instrument for measuring sub-health status in urban Chinese.
authors.affiliation: School of Public Health and Family Medicine, Capital Medical University, Physical Examination Center, Beijing Xuanwu Hospital, Beijing, China.
authors.forename: Yu-Xiang
authors.initials: YX
authors.lastname: Yan
authors.forename: You-Qin
authors.initials: YQ
authors.lastname: Liu
authors.forename: Man
authors.initials: M
authors.lastname: Li
authors.forename: Pei-Feng
authors.initials: PF
authors.lastname: Hu
authors.forename: Ai-Min
authors.initials: AM
authors.lastname: Guo
authors.forename: Xing-Hua
authors.initials: XH
authors.lastname: Yang
authors.forename: Jing-Jun
authors.initials: JJ
authors.lastname: Qiu
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Yang
authors.forename: Jian
authors.initials: J
authors.lastname: Shen
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D002681:China; D003430:Cross-Sectional Studies; D005260:Female; D006304:Health Status; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D014505:Urban Population; D055815:Young Adult