Purpose: To examine the structure, distribution and interrelationships of International Classification of Functioning, Disability and Health (ICF)-compatible items in Australia's national data collection about disability support services.
Method: Rasch analyses were carried out on 93,000 records relating to people aged 15 to 64 years, receiving disability support services in Australia in 2003. The range of disabilities and services received was diverse. 'Support needs', in all nine life areas based on the ICF Activities and Participation domains, are recorded in the national data collection in one of the following three categories: 'needs no help/supervision in this life area'; 'sometimes needs help/supervision'; or 'always needs help/supervision or unable to do activity'.
Results: The results of the analysis demonstrate the value of the 'support needs' questions. The three categories of need for support were distinct and widely separated; the ICF domains were also found to be distinct. The results also showed that 'support needs' in one subset of ICF Activities and Participation domains could not be used to predict values in another subset.
Conclusions: The two-dimensional question about 'support needs' offers promise as a general data capture tool for indicating 'extent' of disability. Caution should be exercised in the omission of any ICF Activities and Participation life areas for measurement in diverse populations.