Table 3.

Avenues for data sourcing in sudden cardiac death registries

	Benefits	Limitations	UCDP Registry implementation
Ambulance-based out-of-hospital cardiac arrest (OHCA) registries	Many countries have well-established OHCA registries (figure 2) and use comparable Utstein variables.	Rates of first-responder reported OHCA have been shown to have significant mismatch when correlated with autopsy (ie, drugs may be responsible for cardiac arrest).25 Over-reporting of true rates will occur if limited to ambulance-reported OHCA only.	Ambulance data will be a key component of the UCDP Registry and a vital source of case detection. Data will be cross-referenced from other sources to enhance internal case verification and data quality.
In-hospital cardiac arrest registers	Most hospitals maintain a ‘Code Blue’ or cardiac arrest registry that can be accessed.	There are over 1300 public and private hospitals in Australia.42 Contacting each hospital and arranging ethical approval for release on in-hospital audits will be prohibitive.	The registry will be an OHCA registry only. The impact of this is discussed further in the article.
Forensic institutes: autopsy data	Autopsy is the gold standard investigation in verifying that a sudden death is cardiac in aetiology.	Rates of autopsy are falling.37 Autopsy-focused registries will capture only a subset of total sudden cardiac deaths.	Will be used to verify rates of sudden cardiac death and cross-reference with ambulance data.
Death certificate tracking	Should represent the broadest way of capturing the denominator as the endpoint.	Reported rates of death due to ‘sudden cardiac death’, ‘cardiac arrest’ and ‘heart failure’ are notoriously high: the positive predictive value of a death certificate stating ‘sudden cardiac death’ is only 19%.26	Needs to be correlated against autopsy data as part of a multiple source surveillance protocol to reduce over-reporting.
Genetic heart disease registries or disease-specific registries (ie, Brugada syndrome)	There will be overlap between patients with genetic heart conditions (and their families) and sudden cardiac death.	Patients already known to have genetic heart disease and enrolled with disease-specific registries will receive appropriate therapy/devices and be anticipated to have a low rate of sudden cardiac death.	Primary utility may be in data linkage or dual referral to both UCDP Registry and disease-specific registry when a death occurs and culprit is identified.

UCDP, Unexplained Cardiac Death Project.