ANZDATA Australia and New Zealand dialysis and transplant registry ANZDATA Australia and New Zealand dialysis and transplant registry

Summary of the ANZDATA data collection by year.

 

These reports show some of the outcomes of dialysis treatment and kidney transplantation performed in Australia and New Zealand. These reports are issue by the Australia and New Zealand Dialysis and Transplant Registry. This Registry, funded by the Australia Organ and Tissue Authority and New Zealand Ministry of Health and Kidney Health Australia, collects information from hospitals on all people treatment with chronic (long-term) dialysis and kidney transplantation.

The primary purpose of these reports is to inform hospitals and others of the outcomes of renal replacement therapy (dialysis and kidney transplantation) in each hospital, and how this compares with other hospitals throughout Australia and New Zealand. They have been produced for a number of years, and hospitals use these reports as part of their Safety and Quality programs. In 2015, for the first time, abridged versions of the reports are being made available for the public, with hospitals identified by name.

The dialysis report includes all patients treated over the period 2008-2013. The tables show the number of patient treated, the number of deaths, and the number of “expected” deaths. From these a “standardised mortality ratio” (SMR) is calculated for each hospital.

The “expected” number is calculated from a formula to adjust for the difference in patient characteristics (for example age, number of patients) between different hospitals which might otherwise lead to erroneous comparisons. The SMR is calculated as . A hospital with a SMR of 1.0 has the same number of deaths as the national average.

For kidney transplantation, the same process is followed, except that the results are counted 1 year after transplantation. Numbers are shown for “graft failure” and “mortality”. “Graft failure” includes situations where a transplant has lost function and the recipient has returned to dialysis, as well as deaths of recipients. “Mortality” includes deaths of transplant recipients in the first 12 months regardless of whether the transplant was functioning at time of death.

Importantly there is random variation in all these events. Other examples of this in the world around us include variation in dice rolls or the number of times a coin comes up heads if flipped. If coin were flipped 10 times, the chances of 5 heads occurring are less than 1 in 4. The chances of varying numbers of heads can be calculated, and is illustrated in the figure.
Based on this concept of random variation, the chances of any given result occurring simply by random chance can be calculated. Statistical convention is that 95% confidence intervals are calculated – this is the range within which the “true” result can be known with 95% confidence. (Conversely, a result outside of these limits would be expected simply by chance 1 time in 20). These are shown both in the table, and are also indicated on the graphs in the report. These graphs also show how random variation is related to the number of patients treated in each hospital.

The versions of these reports on the ANZDATA website are summaries of more comprehensive reports distributed to each unit every year. If there are questions about the methods or content of the report, they can be sent to anzdata@anzdata.org.au.

 

Page updated 27/05/2015