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Open Access Research article

Adjusting for under-identification of Aboriginal and/or Torres Strait Islander births in time series produced from birth records: Using record linkage of survey data and administrative data sources

David Lawrence1*, Daniel Christensen1, Francis Mitrou1, Glenn Draper2, Geoff Davis3, Sybille McKeown4, Daniel McAullay5, Glenn Pearson1 and Stephen R Zubrick1

Author Affiliations

1 Telethon Institute for Child Health Research, Centre for Child Health Research, The University of Western Australia, P.O. Box 855, West Perth, WA, 6872, Australia

2 Australian Bureau of Statistics, GPO Box K881, Perth, WA, 6842, Australia

3 Department of Health, Government of Western Australia, Perth, Australia

4 Australian Bureau of Statistics, PO Box 10, Belconnen, ACT, 2614, Australia

5 Kurongkurl Katitjin, Centre for Indigenous Australian Education and Research, Edith Cowan University, 2 Bradford Street, Mount Lawley, WA, 6050, Australia

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BMC Medical Research Methodology 2012, 12:90  doi:10.1186/1471-2288-12-90

Published: 2 July 2012

Abstract

Background

Statistical time series derived from administrative data sets form key indicators in measuring progress in addressing disadvantage in Aboriginal and Torres Strait Islander populations in Australia. However, inconsistencies in the reporting of Indigenous status can cause difficulties in producing reliable indicators. External data sources, such as survey data, provide a means of assessing the consistency of administrative data and may be used to adjust statistics based on administrative data sources.

Methods

We used record linkage between a large-scale survey (the Western Australian Aboriginal Child Health Survey), and two administrative data sources (the Western Australia (WA) Register of Births and the WA Midwives’ Notification System) to compare the degree of consistency in determining Indigenous status of children between the two sources. We then used a logistic regression model predicting probability of consistency between the two sources to estimate the probability of each record on the two administrative data sources being identified as being of Aboriginal and/or Torres Strait Islander origin in a survey. By summing these probabilities we produced model-adjusted time series of neonatal outcomes for Aboriginal and/or Torres Strait Islander births.

Results

Compared to survey data, information based only on the two administrative data sources identified substantially fewer Aboriginal and/or Torres Strait Islander births. However, these births were not randomly distributed. Births of children identified as being of Aboriginal and/or Torres Strait Islander origin in the survey only were more likely to be living in urban areas, in less disadvantaged areas, and to have only one parent who identifies as being of Aboriginal and/or Torres Strait Islander origin, particularly the father. They were also more likely to have better health and wellbeing outcomes. Applying an adjustment model based on the linked survey data increased the estimated number of Aboriginal and/or Torres Strait Islander births in WA by around 25%, however this increase was accompanied by lower overall proportions of low birth weight and low gestational age babies.

Conclusions

Record linkage of survey data to administrative data sets is useful to validate the quality of recording of demographic information in administrative data sources, and such information can be used to adjust for differential identification in administrative data.