Table 1

Characteristics of cohort study patients with and without morbidities

VariableCategoryNo morbidity n=326 (%)Any morbidity n=340 (%)Total (%)
SexFemale137 (42)155 (47)292 (44)
Male189 (58)185 (53)374 (56)
Income category
(per year)
Up to £10 00031 (9)24 (7)55 (8)
£10 000–£20 00067 (21)87 (25)154 (23)
£20 001–£50 000118 (36)113 (34)231 (35)
More than £50 00073 (22)57 (16)130 (20)
Unknown37 (12)59 (18)96 (14)
Survived beyond 6 monthsYes322 (99)305 (90)627 (94)
No43539 (6)
Hospital centreA79 (24)106 (31)185 (28)
B69 (21)66 (19)135 (20)
C78 (24)78 (23)156 (23)
D68 (21)65 (19)133 (20)
E32 (10)25 (4)57 (9)
EthnicityWhite226 (69)219 (64)445 (67)
Non-white92 (28)99 (31)191 (29)
Missing8 (2)22 (6)30 (5)
Weight for ageNormal212 (65)219 (64)431 (65)
Low90 (28)103 (30)193 (29)
Missing24 (7)18 (5)42 (6)
Premature*No300 (92)306 (90)606 (91)
Yes263460 (9)
Congenital comorbidity*No281 (86)264 (78)545 (82)
Yes4576121 (18)
Pre-existing severity of illness indicators*No277 (85)265 (78)542 (81)
Yes4975124 (19)
Preacquired comorbidity*No279 (85)290 (85)569 (85)
Yes475097 (15)
Down’s syndrome*No299 (92)311 (91)610 (92)
Yes272956 (8)
Pre-existing additional cardiac risk factor†No301 (92)309 (91)610 (92)
Yes253156 (8)
Diagnosis category†A (most complex)40 (12)48 (14)88 (14)
B34 (10)56 (16)90 (14)
C62 (19)62 (18)124 (19)
D89 (27)107 (31)196 (29)
E (least complex)101 (31)67 (20)168 (25)
Procedure category‡A: Palliative/staged65 (19)90 (25)155 (23)
B: Reparative/corrective190 (58)169 (50)359 (54)
C: Ambiguous71 (22)81 (24)152 (23)
Age categoryNeonate114 (35)146 (43)260 (39)
Infant130 (40)120 (35)250 (38)
Child82 (25)74 (22)156 (23)
  • *Comorbidities are: preacquired comorbidity; congenital comorbidity excluding Down’s syndrome; Down’s syndrome, additional cardiac risk factors (eg, cardiomyopathy); prematurity; severity of illness indicator.

  • †Cardiac diagnosis category based on the Partial Risk Adjustment in Surgery (PRAiS2) ranking order and further aggregated by an expert panel, group A the most complex and group E the least (online supplementary appendix 4).

  • ‡Specific procedure category based on National Congenital Heart Disease Audit (NCHDA) algorithm, reparative or corrective operation; palliative or staging operation; ungrouped operation (could not be determined).18