Abstract
Objective: To identify factors associated with critical congenital heart disease (CCHD) one year mortality, with a focus on factors responsible for ethnic disparity in New Zealand (NZ).
Methods: A population-based, retrospective cohort study of CCHD cases in NZ from 2006–2019, where CCHD was defined as live-birth cases who either had cardiac surgery and/or died with significant congenital heart disease within 28 days of birth. The primary outcome was all-cause mortality up to one year of age. Survival analysis by ethnicity to one year of age was undertaken. The relationship of other variables with ethnicity was examined, and associations with one year mortality were defined with univariable and multivariable analysis. Variables inputted into the multivariable model included ethnicity, gestational age at birth, birthweight Z score, cardiac subtype, comorbidities, deprivation index level and management pathway (comfort care or surgical management).
Results: Of the 855,499 total births in NZ from 2006–2019, there were 1,278 CCHD cases (1.5 per 1,000). Fetal diagnosis occurred in 1,121 cases (87.6%) with 237 pregnancy termination decisions (21.1%) and 64 stillbirths (5.7%). The study cohort included 975 live births with 177 deaths prior to one year of age (18.2%). The CCHD survival rate differed by ethnicity with survival higher in European cases than in Indigenous Māori, Pacific, and Asian cases. When adjusting for multiple variables, CCHD mortality risk was no longer associated with ethnic group but was independently associated with a decision to pursue surgical management [aHR 0.07, 95% CI 0.05-0.11], each step increase in deprivation level (from 1-10) [aHR 1.07, 95% CI 1.00-1.14], increasing birthweight Z-score and cardiac diagnosis. All of these factors were distributed inequitably by ethnic group.
Conclusion: Ethnicity was not associated with one year CCHD infant survival when other covariates were accounted for including social circumstance, management pathway and cardiac diagnosis. There is potential to improve CCHD survival and advance equity for minoritized ethnic groups by reducing the impact of modifiable factors through policy and healthcare practice design. A detailed study of decision making prior to intervention may identify reasons for the variation in management pathway by ethnicity.