Abdominal aortic aneurysm repair in New Zealand: a validation of the Australasian Vascular Audit

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Clinical governance and accountability requires that operative outcome data is now routinely collected by national health bodies. The majority of surgical units are also required to collect their own data for reporting, audit and research purposes.
Broadly, there are two types of data sources: administrative and clinical. The accuracy and reliability of each is an important issue, and surgeons need to understand the differences between them. The main purpose of each data set differs, and therefore, the variables recorded, the quality and accuracy are likely to differ.1
Surgeons and health policy decision makers rely on end outcomes such as 30‐day or 1‐year mortality for reporting outcomes. This relatively simple measure can differ depending on the data source. Specifically with cases of abdominal aortic aneurysm (AAA), there is documented variation in 30‐day mortality figures for elective repairs depending on the source of the data: prospective population‐based reported 8.2% compared to 3.8% from prospective hospital‐based.2
The Australasian Vascular Audit (AVA) is a bi‐national web‐based audit and is the official audit for the Australian and New Zealand Society of Vascular Surgery.3 It collects demographical data, risk factors, operative details and outcomes for all inpatient events on vascular patients. Data entry was commenced in January 2010 with gradual uptake from the majority of vascular units at both private and public hospitals in New Zealand (NZ) and has replaced several individual hospital databases and the Otago Clinical Audit from that date. Since 2012, it has been compulsory for vascular surgery trainees to use AVA to generate their operative logbook.
Understanding the quality and accuracy of data captured by the AVA is important as this audit can provide a useful record of AAA repair. Recently, data quality from Australia submitted to the AVA was subjected to internal validation using a random 5% of major arterial cases, and a reported error rate of 2.6% was found. With regards to external validation, the AVA in Australia captures 63% of the data in the public sector and only 51.6% in the private sector.4
The NZ outcome data submitted to the AVA have not been subjected to any form of validation since its introduction. Furthermore, there are very few published contemporary studies of AAA repair outcomes in NZ; the most recent published information reported a 30‐day mortality of 6.7% for elective AAA repaired between 2002 and 2006.5 It is unknown whether this figure included endovascular aneurysm repair (EVAR) or symptomatic but non‐rupture AAA. In addition, this figure is considered relatively high compared to contemporary figures, and greater reliance on EVAR in recent practice is likely to have reduced overall operative mortality rates following elective AAA repair.6
Therefore, the aim of this study was to validate the quality and accuracy of demographic and outcome AAA repair data recorded on the AVA using the Ministry of Health National Administrative Data set.
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