Cross-sectional study of congenital heart disease among Tibetan children aged from 4 to 18 years at different altitudes in Qinghai Province

Background Congenital heart disease (CHD) is a common heart condition which does considerable harm to the health of children and adolescents. CHD epidemiological characteristics of Tibetan children whose ages ranged from 4 to 18 years were investigated in Qinghai Province. Methods A total of 32 578 Tibetan children, living at altitudes of 2535 m, 3600 m and 4200 m, were examined using a three-stage protocol: prescreening, rechecking and diagnosis using a color Doppler. The distribution of CHID at different altitudes was analyzed together with differences in occurrence according to age and gender. Results A total of 235 CHD cases were discovered. The total prevalence of CHD was 7.21 parts per thousand. Prevalence of CHID has been shown to increase along with increase in altitude with 5.45 parts per thousand. at an altitude of 2535 m, 6.80 parts per thousand at 3600 m and 9.79 parts per thousand at 4200 m. There were no statistically significant differences between the prevalence at 2535 m and 3600 m (X-2=11.594, P>0.05). However, there was a significant difference between the prevalence at 2535 m and 4200 m (X-2=7.002, P <0.01). Also, apparent differences existed between the prevalence at 3600 m and at 4200 m (X(2=)5.540, P <0.05). There was no statistically significant difference in prevalence according to age at an altitude of 2535 m, but the rate of CHD increased significantly along with increasing age at 3600 m and 4200 m. The total prevalence ratio of children aged from 16 to 18 years was significantly higher than that of children from 4 to 7, and from 8 to 12 with X-2 values of 10.79 (P<0.005), and 5.60 (P<0.05) respectively. Within the constituent ratio of CHID, the prevalence of atrial septal defect (ASD) was the highest at 39.10%, followed by the prevalence of ventricular septal defect (VSD) at 32.8% and patent ductus arteriosus (PDA) at 24.7%. Furthermore the proportion of the four categories of CHD varied at different altitude levels: at 2535 m, of those diagnosed with CHID, the prevalence rate of VSD was the highest at 43.5%, at 3600 m ASD was the highest at 42.8% and at 4200 m, PDA was the highest at 50.8%. Conclusion The epidemiological characteristics of CHID in Tibetan children may be associated with altitude levels.