Patient-specific characteristics by diagnostic group (n = 3897).

Notes:*excludes 144 children who did not have an intervention;†Number (%) of children with missing data: Sex n = 129(3%); Unstable clinical status n = 1784(46%); age at first procedure n = 50(1% of 3753 children who had an intervention); Preterm birth/Down's syndrome (DS)/Non-DS non-cardiac malformations/Additional cardiac defects: no missing data.Key: IQR interquartile range; preterm Add. cardiac defects - in addition to primary CHD diagnosis; unstable clinical status on first admission was defined as unstable if one or more of the following symptoms/signs were present: unwell = significant pallor, breathlessness or sweating, intubated, mechanically ventilated, hypotension = systolic blood pressure [SBP] 100 mmHg, cardiac or respiratory arrest, metabolic acidosis, requiring adrenaline or high dose inotropic support; HLH/MA hypoplastic left heart and/or mitral atresia; TA tricuspid atresia; DIV double inlet ventricle; PA+IVS pulmonary atresia with intact ventricular septum; PA+VSD pulmonary atresia with ventricular septal defect; CAT common arterial trunk; CAVSD complete atrioventricular septal defect; TGA transposition of the great arteries; TOF tetralogy of Fallot; TAPVC total anomalous pulmonary venous connection; VSD ventricular septal defect; AS aortic stenosis; PS pulmonary stenosis; COA coarctation of the aorta; Misc miscellaneous cardiac defects (not included within other categories).Patient-specific characteristics by diagnostic group (n = 3897).