Limitations:
Administrative databases provide the benefit of including large groups of patients across the nation and can be helpful in obtaining large samples sizes for rare diseases or rare outcomes. However, they lack the clinical details and are susceptible to coding errors. This study is based on assumptions formed by diagnostic codes and hence the conclusions may be prone to errors. This study also represents the hospitalizations and not individual patients. However, in-hospital deaths would represent individual patients. We cannot determine the events that lead to the in-hospital death or the actual cause of death. We are also not able to discern the type of ICD (single chamber vs dual chamber) and whether the ICD was utilized, i.e. delivered an appropriate shock, during the admission. It is also difficult to determine the specific forms of congenital heart disease (for example patients with single ventricular physiology vs biventricular repairs), precluding us from stratifying patients into risk categories. Lastly, since only hospital data is available, outcomes such as death after discharge or readmission rates cannot be determined.