Comparison of under-5 mortality in England and in Sweden using electronic birth cohorts from administrative linked data
Zylbersztejn, A., Gilbert, R., Hjern, A. & Hardelid, P. (2017) UK Administrative Data Research Network Annual Research Conference, Royal College of Surgeons, Edinburgh, UK, 1 - 2 June 2017
Under-5 mortality in England is almost two times higher than in Sweden. Policy makers need to know which interventions would be most effective at reducing child mortality rates to those of Sweden: addressing risk factors at birth (such as preterm birth or low birthweight), or improving care after birth. This study uses electronic birth cohorts to determine whether inter-country differences are driven by risk factors operating before or after birth.
We developed cohorts of singleton live births using Hospital Episode Statistics, linked to the Office for National Statistics mortality data in 2003-2012, in England, and using Medical Birth Register, linked to Hospital Discharge Register and Cause of Death Register in 1998-2012, in Sweden. We fitted Cox Proportional Hazards models to estimate hazard ratios (HR) for England versus Sweden for neonatal (2-27 days), post-neonatal (28-364 days) and early-childhood (1-4 years) mortality, excluding deaths on days 0-1 due to inter-country differences in registration practices. The models were adjusted for risk factors at birth (gestation, birthweight, gender, congenital anomalies), and socio-economic factors (maternal age and socio-economic status).
The study cohorts comprised 3,940,168 births and 11,360 deaths in England and 1,436,211 births and 2,947 deaths in Sweden. The unadjusted HR for England vs Sweden in the neonatal period was 1.50 (95% Confidence Interval: 1.40-1.61). HR decreased to 1.02 (0.95-1.10) after adjusting for risk factors at birth, and to 0.99 (0.92-1.06) after further adjustment for socio-economic factors. In post-neonatal period the HRs were 1.50 (1.41-1.60), 1.11 (1.04-1.18) and 1.01 (0.95-1.08), respectively. In early-childhood the HRs were 1.21 (1.11-1.31), 1.04 (0.96, 1.13) and 0.98 (0.90, 1.07), respectively.
Differences in under-5 mortality in England relative to Sweden were primarily driven by a higher prevalence of risk factors at birth. Policies to reduce under-5 mortality in England should focus on health of women before and during pregnancy to reduce preterm birth, low birthweight, and prevalence of congenital anomalies.