Table 2

Propensity Matching for Controls and CHD Patients

Matching CriteriaBefore MatchingAfter Matching
CHD
(n = 4,520)
Controls
(n = 46,488)
p ValueCHD
(n = 4,494)
Controls
(n = 4,494)
p Value
Male2,516 (56)26,689 (57)0.022,516 (56)2,516 (56)1.00
Age groups<0.0011.00
 <6 months1,668 (37)5,648 (12)1,642 (36)1,642 (36)
 6–12 months519 (11)3,633 (8)519 (12)519 (12)
 1–6 yrs1,186 (26)12,546 (27)1,186 (26)1,186 (26)
 6–12 yrs614 (14)12,128 (26)614 (14)614 (14)
 >12 yrs533 (12)12,533 (27)533 (12)533 (12)
ASA class 3 or 43,260 (72)8,938 (19)<0.0013,234 (72)3,234 (72)1.00
Elective surgery3,624 (80)34,105 (73)<0.0013,598 (80)3,598 (80)1.00
Operative complexity15 (10–21)11 (9–16)<0.00114 (9–21)14 (9–21)1.00

Values are n (%) or median (interquartile range). Operative complexity was defined for each procedure using the relative value unit based on current procedure terminology codes. p values in bold are statistically significant imbalance between the 2 groups, chi-square test.

ASA = American Society of Anesthesiologists; CHD = congenital heart disease.