Linking a European cohort of children born with congenital anomalies to vital statistics and mortality records: A EUROlinkCAT study

Abstract

EUROCAT is a European network of population-based congenital anomaly (CA) registries. Twenty-one registries agreed to participate in the EUROlinkCAT study to determine if reliable information on the survival of children born with a major CA between 1995 and 2014 can be obtained through linkage to national vital statistics or mortality records. Live birth children with a CA could be linked using personal identifiers to either their national vital statistics (including birth records, death records, hospital records) or to mortality records only, depending on the data available within each region. In total, 18 of 21 registries with data on 192,862 children born with congenital anomalies participated in the study. One registry was unable to get ethical approval to participate and linkage was not possible for two registries due to local reasons. Eleven registries linked to vital statistics and seven registries linked to mortality records only; one of the latter only had identification numbers for 78% of cases, hence it was excluded from further analysis. For registries linking to vital statistics: six linked over 95% of their cases for all years and five were unable to link at least 85% of all live born CA children in the earlier years of the study. No estimate of linkage success could be calculated for registries linking to mortality records. Irrespective of linkage method, deaths that occurred during the first week of life were over three times less likely to be linked compared to deaths occurring after the first week of life. Linkage to vital statistics can provide accurate estimates of survival of children with CAs in some European countries. Bias arises when linkage is not successful, as early neonatal deaths were less likely to be linked. Linkage to mortality records only cannot be recommended, as linkage quality, and hence bias, cannot be assessed.

Survival of children with rare structural congenital anomalies: a multi-registry cohort study

“…All liveborn children with a major CA born between 1 st January 1995 and 31 st December 2014 recorded in the 13 registries of nine Western European countries were linked to mortality records up to the child’s 10 th birthday or to 31 st December 2015 (whichever was earlier), so that all live births had information on at least the first year’s survival (Table 1 ). Full details on the linkage methods are reported elsewhere [ 21 – 23 ]. A major CA is defined as an anomaly that require surgical treatment, have serious adverse effects on health or development, or have significant cosmetic impact [ 24 ].…”

“…Linkage to vital statistics provides information on whether the child was still alive or had died; in contrast, in a mortality database the child was assumed to be alive if no death certificate was present. Careful examination of the accuracy of the linkage was undertaken and birth years in registries during which the linkage quality was judged poor were excluded from this analysis [ 21 ]. The study period differed between registries due to different years of EUROCAT membership and because only years with high quality linkage were retained (Table 1 ).…”

“…The analyses were based on standardized EUROCAT variables together with a common data model developed for EUROlinkCAT to standardize the local variables obtained from the linkage [ 17 ]. Such standardization allowed centrally written syntax scripts to be developed both for checking the quality of data linkage and for analysing the data to be run by all participating registries [ 17 , 21 ].…”

Gastrostomy and congenital anomalies: a European population-based study

“…We included children up to 5 years of age in this study as the number of children reaching the age of 10 years with the specific congenital anomalies under consideration was limited. Details of the methods used in the EUROlinkCAT Study including the linkage methods have been published elsewhere 10 11…”

COVID‐19 in pregnancy—what study designs can we use to assess the risk of congenital anomalies in relation to COVID‐19 disease, treatment and vaccination?

“…77 Quality of establishment of study population of mother-baby dyads Several countries, for example the Nordic countries and Scotland, have a mother-baby linkage spine which identifies the healthcare number of the mother for each baby. The most successful linkage uses unique identification (ID) number provided at birth for every individual in the population, but biases may still be present (e.g., preterm babies dying before being allocated an ID number) 79 and TOPFA may remain unlinked. Studies which conduct linkage based on non-unique matching variables may have a large proportion of unlinked or incorrectly linked pairs.…”