Factors Associated With Ethnic Disparities in 1-Year Survival With Critical Congenital Heart Disease in New Zealand

OBJECTIVE We aim to identify factors associated with critical congenital heart disease (CCHD) 1-year mortality rate, 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 to 2019, in which 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 aged 1 year. Survival analysis by ethnicity to aged 1 year was undertaken. The relationship of other variables with ethnicity was examined, and associations with the 1-year mortality rate were defined with univariable and multivariable analysis. Variables inputted into the multivariable model included ethnicity, gestational age at birth, birth weight 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 to 2019, there were 1278 CCHD cases (1.5 per 1000). Fetal diagnosis occurred in 1121 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 before aged 1 year (18.2%). The CCHD survival rate differed by ethnicity with survival higher in European cases than in Indigenous Māori, Pacific Islander, 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 (adjusted hazard ratio [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 birth weight z score, and cardiac diagnosis. All of these factors were distributed inequitably by ethnic group. CONCLUSION Ethnicity was not associated with 1-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 health care practice design. A detailed study of decision-making before intervention may identify reasons for the variation in management pathway by ethnicity.