Characteristics of the underlying study population
| Variables | n (%) |
| Age group (years) (n=3903) | |
| 18–34 | 1663 (42.6) |
| 35–64 | 1733 (44.4) |
| 65+ | 507 (13.0) |
| Gender (n=3898) | |
| Male | 2087 (53.5) |
| Female | 1811 (46.5) |
| Residence (n=3855) | |
| City | 775 (20.1) |
| Town | 590 (15.3) |
| Rural | 2490 (64.6) |
| Insurance (n=3905) | |
| Public | 3679 (94.2) |
| Private | 219 (5.6) |
| No insurance | 7 (.2) |
| Type of congenital heart defect (CHD) (n=4014) | |
| Complex congenital heart defects | 581 (14.5) |
| Primary pretricuspid shunts | 621 (15.5) |
| Primary post-tricuspid shunts | 406 (10.1) |
| Right heart/pulmonary artery anomalies | 526 (13.1) |
| Left heart/aortic anomalies | 898 (22.4) |
| Miscellaneous CHD | 602 (15.0) |
| Unclassifiable | 380 (9.5) |
| Warnes class (n=2778) | |
| Simple | 1722 (62.0) |
| Moderate | 650 (23.4) |
| Severe | 406 (14.6) |