The Use of Health Administrative Data in Intellectual Disability Research in Australia: A Scoping Review

BACKGROUND: Health administrative data are increasingly used to investigate physical and mental health disparities experienced by people with intellectual disability worldwide. However, approaches to identifying people with intellectual disability differ across studies, complicating knowledge translation and policymaking. This scoping review aims to map the Australian health administrative data sources and case ascertainment methods used to identify intellectual disability, and to examine their strengths and limitations. METHOD: We conducted a scoping review of studies that ascertain people with intellectual disability using at least one Australian health administrative dataset. A total of 1075 articles were identified through searches in Embase, PubMed and PsycINFO. The databases and algorithms used to ascertain intellectual disability diagnosis were extracted from the included papers. RESULTS: Forty-one studies were included, identifying six categories of health administrative datasets, most commonly birth defects registries, hospitalisation data and mental health service data, with substantial variation across states or territories. In the health datasets, intellectual disability was often coded using ICD diagnostic codes, although reporting of coding methods was inconsistent. Studies frequently linked health datasets with disability service data sources to improve case ascertainment, with a median of two datasets per study (range: 1-9). The most common study outcome was health service utilisation. Frequently reported strengths of linking multiple datasets included large, population-based samples and the capacity for longitudinal and comparative study designs, while underascertainment remained an issue, particularly for those with a milder form of intellectual disability. CONCLUSIONS: Health administrative data are a valuable resource for intellectual disability research in Australia, but methodological challenges persist, particularly in incomplete ascertainment of people with intellectual disability and inconsistency across jurisdictions. A unified national approach to data collection and analysis is needed to improve comparability across evidence and better support evidence-informed practice and policy.