| Abstract | A methodology for linking vital statistics linked birth/death data and hospital discharge data
is described. The resulting data set combines information on a neonate's sociodemographic
characteristics, prenatal care, and mortality aspects and connects it to detailed health
outcome and resource utilization data, thus establishing an extensive database for
epidemiological studies. In the absence of a universal identifier common to both databases,
our linkage strategy relied on using a virtual identifier based on variables common to both
data sets. In the case of multiple incidences of the same virtual identifier we used secondary
health status information to optimize the likelihood of linking low birth weight or premature
infants in one database to infants of similar health status in the other while randomizing
cases in which no secondary information was present. Applying our method to the 1992
California birth cohort, we could link 563,114 out of 571,189 eligible births (98.59%). Of
these links, 91.2% were established on the basis of unique virtual identifiers. The link was
internally consistent and no bias was evident when comparing variable distributions for all
single live births in the vital statistics linked birth/death file and linked births in the linked
vital statistics linked birth/death and hospital discharge file. Multiple imputation techniques
showed that the prediction error incurred by randomization was negligible. Even though
computationally intensive, our method for linking the vital statistics linked birth/death file
and the hospital discharge file appeared to be effective. However, it is important to be
aware of the limitations of the resulting data set, in particular the fact that it cannot be used
for tracking individual cases. The method provides a database suitable for a variety of
perinatal epidemiological analyses, such as descriptive studies of disease distribution in
neonates, studies of the geographic distribution of disease, and studies of the relationship
between risk and outcome. |