Impact of Socioeconomic Status and Residence Distance on Infant Heart Disease Outcomes in Canada

Abstract

Background Socioeconomic status (SES) impacts clinical outcomes associated with severe congenital heart disease (sCHD). We examined the impact of SES and remoteness of residence (RoR) on congenital heart disease (CHD) outcomes in Canada, a jurisdiction with universal health insurance. Methods and Results All infants born in Canada (excluding Quebec) from 2008 to 2018 and hospitalized with CHD requiring intervention in the first year were identified. Neighborhood level SES income quintiles were calculated, and RoR was categorized as residing <100 km, 100 to 299 km, or >300 km from the closest of 7 cardiac surgical programs. In-hospital mortality at <1 year was the primary outcome, adjusted for preterm birth, low birth weight, and extracardiac pathology. Among 7711 infants, 4485 (58.2%) had moderate CHD (mCHD) and 3226 (41.8%) had sCHD. Overall mortality rate was 10.5%, with higher rates in sCHD than mCHD (13.3% versus 8.5%, respectively). More CHD infants were in the lowest compared with the highest SES category (27.1% versus 15.0%, respectively). The distribution of CHD across RoR categories was 52.3%, 21.3%, and 26.4% for <100 km, 100 to 299 km, and >300 km, respectively. Although SES and RoR had no impact on sCHD mortality, infants with mCHD living >300 km had a higher risk of mortality relative to those living <100 km (adjusted odds ratio [aOR], 1.43 [95% CI, 1.11-1.84]). Infants with mCHD within the lowest SES quintile and living farthest away had the highest risk for mortality (aOR, 1.74 [95% CI, 1.08-2.81]). Conclusions In Canada, neither RoR nor SES had an impact on outcomes of infants with sCHD. Greater RoR, however, may contribute to higher risk of mortality among infants with mCHD.

Keywords: clinical outcomes; congenital heart disease; population; remoteness of residence; socioeconomic status.

Figure 1. Population of infants with CHD included in the analyses.

AVSD indicates atrioventricular septal defect; CHD, congenital heart disease; and VSD, ventricular septal defect.

Figure 2. Mortality by SES and RoR categories among infants with moderate and severe congenital heart disease.

Unadjusted proportions in mortality by SES quintile (top) and RoR category (bottom). For moderate congenital heart disease, SES (P=0.034) and RoR (P=0.044) were associated with mortality, a finding not true for severe congenital heart disease (P=0.092 and P=0.13, respectively). RoR indicates remoteness of residence; and SES, socioeconomic status.

Figure 3. Multivariable analyses of the separate effects of SES and RoR on mortality.

References: Quintile 5 for SES and <100 km for RoR category. Mortality was associated with covariates (preterm birth, low birth weight, extracardiac anomalies) in SES and RoR models. Mortality was associated with increasing RoR for moderate CHD (P=0.022) but not for severe CHD (P=0.31) or with SES for either complexity group (moderate CHD, P=0.066; severe CHD, P=0.18). Dotted lines indicate odds ratio and solid lines indicate 95% confidence intervals. CHD indicates congenital heart disease; RoR, remoteness of residence; and SES, socioeconomic status.

Figure 4. Multivariable model of SES quintile and RoR extremes on mortality.

References: Quintile 5 for SES and <100 km for RoR category. Mortality was associated with the interaction of distance and income in moderate (P=0.003) but not severe congenital heart disease (P=0.22). Dotted lines indicate odds ratio and solid lines indicate 95% confidence intervals. RoR indicates remoteness of residence; and SES, socioeconomic status.

Figure 5. Impact of SES and RoR on hospital length of stay at first intervention.

References: Quintile 5 for SES and <100 km for RoR category. SES quintile (moderate CHD, P<0.0001; severe CHD, P<0.0007) and RoR category (moderate CHD, P=0.0001; severe CHD P=0.047) were associated with differences in length of stay at first intervention after adjusting for mediators. Dotted lines indicate rate ratio and solid lines indicate 95% confidence intervals. CHD indicates congenital heart disease; RoR, remoteness of residence; and SES, socioeconomic status.

Figure 6. Impact of SES and RoR on hospital counts in the first year.

References: Quintile 5 for SES and <100 km for RoR category. RoR was associated with fewer hospital counts in the first year (P=0.0004). No other associations reached statistical significance. Dotted lines indicate rate ratio and solid lines indicate 95% confidence intervals. RoR indicates remoteness of residence; and SES, socioeconomic status.