title: Exploration of ecological factors related to the spatial heterogeneity of tuberculosis prevalence in P. R. China.
abstract: BACKGROUND
  The current prevalence of tuberculosis (TB) in the People's Republic of China (P. R. China) demonstrates geographical heterogeneities, which show that the TB prevalence in the remote areas of Western China is more serious than that in the coastal plain of Eastern China. Although a lot of ecological studies have been applied in the exploration on the regional difference of disease risks, there is still a paucity of ecological studies on TB prevalence in P. R. China.
  
  
  OBJECTIVE
  To understand the underlying factors contributing to the regional inequity of TB burden in P. R. China by using an ecological approach and, thus, aiming to provide a basis to eliminate the TB spatial heterogeneity in the near future.
  
  
  METHODS
  Latent ecological variables were identified by using exploratory factor analysis from data obtained from four sources, i.e. the databases of the National TB Control Programme (2001-2010) in P. R. China, the China Health Statistical Yearbook during 2002-2011, the China Statistical Yearbook during 2002-2011, and the provincial government websites in 2013. Partial least squares path modelling was chosen to construct the structural equation model to evaluate the relationship between TB prevalence and ecological variables. Furthermore, a geographically weighted regression model was used to explore the local spatial heterogeneity in the relationships.
  
  
  RESULTS
  The latent ecological variables in terms of 'TB prevalence', 'TB investment', 'TB service', 'health investment', 'health level', 'economic level', 'air quality', 'climatic factor' and 'geographic factor' were identified. With the exception of TB service and health levels, other ecological factors had explicit and significant impacts on TB prevalence to varying degrees. Additionally, each ecological factor had different impacts on TB prevalence in different regions significantly.
  
  
  CONCLUSIONS
  Ecological factors that were found predictive of TB prevalence in P. R. China are essential to take into account in the formulation of locally comprehensive strategies and interventions aiming to tailor the TB control and prevention programme into local settings in each ecozone.
authors.affiliation: National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, People's Republic of China; Key Laboratory of Parasite and Vector Biology, Ministry of Health, WHO Collaborating Centre for Malaria, Schistosomiasis and Filariasis, Shanghai, People's Republic of China; National Center for Tuberculosis Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China.
authors.forename: Xin-Xu
authors.initials: XX
authors.lastname: Li
authors.affiliation: National Center for Tuberculosis Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China; wanglx@chinatb.org.
authors.forename: Li-Xia
authors.initials: LX
authors.lastname: Wang
authors.affiliation: School of Mathematics and Physics, North China Electric Power University, Beijing, People's Republic of China.
authors.forename: Juan
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Epidemiology and Health Statistics, School of Public Health, Shandong University, Jinan, People's Republic of China.
authors.forename: Yun-Xia
authors.initials: YX
authors.lastname: Liu
authors.affiliation: National Center for Tuberculosis Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: National Center for Tuberculosis Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China.
authors.forename: Shi-Wen
authors.initials: SW
authors.lastname: Jiang
authors.affiliation: National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, People's Republic of China; Key Laboratory of Parasite and Vector Biology, Ministry of Health, WHO Collaborating Centre for Malaria, Schistosomiasis and Filariasis, Shanghai, People's Republic of China.
authors.forename: Jia-Xu
authors.initials: JX
authors.lastname: Chen
authors.affiliation: National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, People's Republic of China; Key Laboratory of Parasite and Vector Biology, Ministry of Health, WHO Collaborating Centre for Malaria, Schistosomiasis and Filariasis, Shanghai, People's Republic of China; xiaonongzhou1962@gmail.com.
authors.forename: Xiao-Nong
authors.initials: XN
authors.lastname: Zhou
mesh_terms: D002681:China / Q000453:epidemiology; D004463:Ecology / Q000706:statistics & numerical data; D062306:Geography, Medical; D006801:Humans; D008954:Models, Biological; D015995:Prevalence; D012307:Risk Factors; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology*
keywords: P. R. China; ecological factor; prevalence; spatial heterogeneity; tuberculosis