Female sex as a risk factor for in-hospital mortality among children undergoing cardiac surgery

Abstract

Background - The purpose of this study was to investigate whether sex disparity in cardiovascular outcomes exists in children who undergo cardiac surgery. Methods and Results - Statewide hospital discharge data from California from 1995 to 1997 were used. Children <21 years old who had a procedure code (by ICD9-CM) that indicated cardiac surgery were selected. The outcome variable was binary, in-hospital death versus alive at discharge. Twenty-three surgical procedures were selected and adjusted for risk by procedure type. We used logistic regression analysis to evaluate the effect of sex on in-hospital mortality, controlling for age, race and ethnicity, type of insurance, home income, type of admission, date and month of surgery, hospital case volume, and type of procedure. There were 6593 cases of cardiac surgery, with 345 in-hospital deaths (mortality rate 5.23%). Crude mortality rates for males (4.98%) and females (5.54%) were not significantly different. However, fewer females were neonates, and females had more low-risk procedures than males. Multivariate logistic regression showed that females had a higher odds ratio (OR) for mortality than males (OR 1.51, P<0.01). The OR for mortality was 3.86 for neonates and 2.98 for infants compared with children aged ≥1 year. Low-volume hospitals had higher mortality rates than high-volume hospitals (OR 1.67, P<0.01). The risk-adjusted length of hospital stay and charges were similar between females and males. Conclusions - For children undergoing cardiac surgery, female sex was associated with 51% higher odds of death than male sex. The mechanism by which female sex acts as a risk factor requires further investigation.