Supplemental Data:
KID Database:
Data in the KID are stratified by geographic region, location/teaching
status, bed size category, and whether the hospital is a freestanding
children’s hospital. Discharges are also stratified by uncomplicated
in-hospital births, complicated in-hospital births, and non-newborn
pediatric discharges. Discharge weights are created for each stratum in
proportion to the known number of American Hospital Association
discharges nationally (Normal newborns were sampled at a rate of 10%,
while complicated newborns and other pediatric discharges were sampled
at a rate of 80%) and using the discharge weights, individual
observations are extrapolated to produce national estimates . Prior to
the KID 2016, diagnostic (CM) and procedural codes (PCS) were reported
using the
International
Classification of Diseases, Ninth revision (ICD-9) codes and starting
with 2016, the ICD-10-CM/PCS coding system was used .
Supraventricular arrhythmias such as atrial flutter/fibrillation codes
were not included in the primary arrhythmia group. Heart transplant
codes were included in the ‘Other’ category even if they had diagnoses
of cardiomyopathy or arrhythmias. Since not all cardiomyopathy disorders
are associated with systolic heart failure (example Hypertrophic
Cardiomyopathy or Arrhythmogenic Cardiomyopathy), we did not assume that
cardiomyopathy diagnostic categories were necessarily associated with
heart failure. We therefore also explored the presence of heart failure,
which for this study was defined by heart failure diagnostic codes or
codes identifying the implantation or presence of mechanical support
(Veno-arterial extracorporeal membrane oxygenation or Ventricular assist
device). Codes for ICD infection, lead fracture, pneumothorax,
hemothorax, mechanical complication of ICD or need for ICD-revision were
used to define the composite variable of ICD complication. The primary
outcome was in-hospital death.