In 1988, Barer, with colleagues from UBC, BC Cancer Agency, and BC Ministry of Health began the BC Linked Health Data Project (BCLHDP), which "was designed to capture the power of linkable and longitudinal data, and avoid the inefficiencies associated with project-by-project data linkage".
In addition, participants admitted to a hospital were identified by their unique National Health Service number by data linkage with ENCORE (East Norfolk Health Authority database), which identifies all hospital contacts throughout England and Wales for Norfolk residents.
One of the main strengths is having a large study population followed with respect to hip fracture by data linkage to a nationwide validated hip fracture database (NORHip).
The impact of this limitation could be minimised by internal data linkage such as linking all of a mother's births to check the Indigenous identification.
Many of the challenges faced by Needleman and his team [ 9] in the matching of data is obviated by the data linkage processes in Western Australia (WA), whereby all patients have a unique identifier that links their individual records into a single 'chain' of hospitalisation episodes.
A multilevel data linkage study by Randall et al. (2012) examined mortality risk following myocardial infarction in Aboriginal and non-Aboriginal people in NSW [ 29].
The linkage of identifying data is conducted by the data linkage branch at the Western Australian Department of Health and subsequent de-identified data are given to the researcher.
Nevertheless, quality assurance practices performed by the data linkage units can result in high sensitivity and specificity (eg, hepatitis linkage sensitivity >99.9%, specificity 99.8%).
13 We linked the records of all people included in the Perth MONICA register to a file of all hospital admissions for cardiovascular disease and related deaths in Western Australia from 1980-2005 ustandardndard linkage procedures developed by the data linkage unit in the Department of Health of Western Australia.
Participants admitted to hospital were identified by their unique national health service number by using data linkage with ENCORE (East Norfolk Health Authority database), which identifies all hospital contacts throughout England and Wales for Norfolk residents.
