title: [A cross-sectional study of congenital heart disease among children aged from 4 to 18 years at different altitudes in Qinghai province, China].
abstract: OBJECTIVE
  The epidemiological characteristics of congenital heart disease (CHD) in children aged from 4 to 18 years were investigated in Qinghai province.
  
  
  METHODS
  Altogether 288 066 children inhabiting at 6 prefectures and 3 counties were examined by the following three steps: pre-screening, re-examination and diagnosis with color Doppler. And the entity distribution was analyzed while the differences were compared by age, gender, altitudes and nationalities respectively.
  
  
  RESULTS
  Altogether 1633 cases of CHD were discovered. The total prevalence of CHD was 5.71 per thousand. The prevalence of CHD was found to increase with the increase of altitude by 4.89 per thousand at the altitude of 2535 m, 5.71 per thousand at 3600 m, and 8.74 per thousand at 4200 m respectively. There were significant differences among different altitude (chi(2) = 54.696, P < 0.001). chi(2) trend analysis showed the increase with chi(2) = 41.826(P < 0.001). The total incidence of CHD in females was 6.95 per thousand, which was significantly higher than that in males with 4.54 per thousand (chi(2) = 73.79, P < 0.001). There were significant differences between males and females at the altitude of 3000 m (chi(2) = 84.733, P < 0.001) and 4000 m (chi(2) = 16.313, P < 0.001) except at the altitude of 2000 m (chi(2) = 0.807, P > 0.05). The prevalence of CHD in different age groups was statistically significant at the every altitude of 2000 m (chi(2) = 18.138, P < 0.001), 3000 m (chi(2) = 18.544, P < 0.001) and 4000 m (chi(2) = 27.535 P < 0.001). The prevalence of CHD was increasing with the increase of age groups at the altitude of 3000 m (chi(2) = 19.230, P < 0.001) and 4000 m (chi(2) = 26.894, P < 0.001) except at the altitude of 2000 m. Within the prevalence of CHD of different nationalities, there was a significant difference with chi(2) = 24.456 (P < 0.001). Within the constituent rate of CHD, the prevalence of atrial septal defect (ASD) was as high as 37.42%, followed by the prevalence of patent ductus arteriosus (PDA) as 28.47% and ventricular septal defect (VSD) as 26.01%. Regarding the four categories of CHD, the constituent rate varied at different altitudes. For example, the prevalence rate of ASD constituted 37% at the altitude of 2000 m and 3000 m, and that of PDA accounted for 46.36% at the altitude of 4200 m.
  
  
  CONCLUSIONS
  The epidemiological characteristics of CHD in Qinghai children were possibly associated with altitude levels.
authors.affiliation: Qinghai Cardio-Cerebrovescular Disease Special Hospital, Xining 810012, China.
authors.forename: Qiu-hong
authors.initials: QH
authors.lastname: Chen
authors.forename: Feng-yun
authors.initials: FY
authors.lastname: Liu
authors.forename: Xiao-qin
authors.initials: XQ
authors.lastname: Wang
authors.forename: Guo-rong
authors.initials: GR
authors.lastname: Qi
authors.forename: Pin-fa
authors.initials: PF
authors.lastname: Liu
authors.forename: Xin-hui
authors.initials: XH
authors.lastname: Jin
authors.forename: Lin
authors.initials: L
authors.lastname: Lu
authors.forename: Guo-qiang
authors.initials: GQ
authors.lastname: Zhao
authors.forename: Sheng-gui
authors.initials: SG
authors.lastname: Qi
mesh_terms: D000293:Adolescent; D000531:Altitude; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006330:Heart Defects, Congenital / Q000453:epidemiology*; D006801:Humans; D008297:Male; D015995:Prevalence