Tā mātou e tūhura ana
What we are investigating
Take | Issue
Politicians, policymakers and planners rely on robust data and research evidence to improve health services for our population. Aotearoa New Zealand has a rich resource of big data sets, available – in anonymised form – through the Statistics New Zealand Integrated Data Infrastructure (IDI).
A major gap in the IDI is primary healthcare data, which is particularly valuable for understanding the full clinical pathway for non-communicable diseases and examining potential service failure.
Another problem is that the power of big data relies on a huge number of data linkages, and errors can occur in matching records belonging to the same person. Data linkage errors are often correlated with ethnicity, which reduces the value of big and linked data for studies of health inequities.
Whāinga | Aim
This project had dual aims. At a foundational level, it aimed to improve the data available for future health research by investigating ways to address data linkage errors in the IDI, and by examining primary care laboratory test data linked to health data.
A further aim was to reduce inequities in stomach cancer death rates in New Zealand, which vary up to six-fold by ethnicity. By analysing the current testing and treatment of Helicobacter pylori (H. pylori) infection, the major contributor to inequitable stomach cancer outcomes, this project sought to provide evidence to support the New Zealand Cancer Action Plan 2019-2029 aim to address H. pylori infection in priority populations.
Huarahi I Whāia | Approach
The first part of the study examined the extent of data linkage error and linkage bias in the IDI on measures of ethnic inequalities in cardiovascular disease, cancer and diabetes. It investigated whether correcting for linkage errors would change estimates of inequitable outcomes for these non-communicable diseases.
The second part of the study examined the feasibility and value of linking community laboratory test data to the wider health data system, using the testing and treatment of H. pylori infection as a model.
NGA PUTANGA ME TE PĀNGA
OUTCOMES AND IMPACT
Outcome | Putanga
The findings of the second part of the study have highlighted substantial ethnic inequities, particularly the disproportionately limited access to testing for Pacific people in New Zealand. This analysis provides a rationale for future H. pylori test-and-treat pilot programmes in priority groups and is expected to help to inform their development.
Next Steps | Te ara kei mua
Work on the first part of the study was extended to June 2025. When completed, the implications of this work for the monitoring and measurement of NCD rates for ethnic groups will be discussed with colleagues at Te Whatu Ora.
Team members involved in the second study have been invited to join a working group of the International Agency for Research on Cancer, which will publish global advice on the implementation of population-based H. pylori test-and-treat strategies to prevent gastric cancer in February 2025.
Research Products | Nga hua o te rangahau
Statistic code from the data linkage bias study will be made available to other users via the IDI and the Virtual Health Information Network.
