Australian Health Survey, 2011-12
The Australian Health Survey (AHS), conducted by the Australian Bureau of Statistics in 2011-12, is made up of three components:
- the National Health Survey (NHS) 2011-12;
- the National Nutrition and Physical Activity Survey (NNPAS) 2011-12; and
- the National Health Measures Survey (NHMS) 2011-12.
All people selected in the AHS were selected into either the NHS or the NNPAS; however, data items in the core were common to both surveys and therefore information for these data items is available for all persons in the AHS. All people aged 5 years and over were then invited to participate in the voluntary NHMS.
Around 20,500 people participated in the NHS, answering questions about items such as detailed health conditions, health related actions and medications, in addition to all items in the core content. For the NHS component (those items collected only in the NHS and not the core), the sample size is similar to that of previous National Health Surveys and therefore the results are comparable. However, for those items collected in the core, the sample size (32,000 people - results for which are published in Australian Health Survey: Updated Results, 2011-12 [ABS Cat. no. 4364.0.55.003]) is approximately 1.5 times that in the past and therefore the estimates for core items such as smoking and Body Mass Index are more accurate, particularly at finer disaggregations, than in previous surveys.
The 2011-12 NHS and NNPAS collect data on a broad range of health conditions a person may have, with the primary focus on current and long-term conditions. A long-term condition is defined as a condition that is current and has lasted, or is expected to last, for 6 months or more. Some conditions, including National Health Priority Area (NHPA) conditions, are specifically asked in individual modules to ensure high quality detailed results for these conditions.
The following two NHPA conditions, as well as kidney disease, were collected in both NHS and NNPAS and therefore information is available for the larger core sample:
- heart and circulatory conditions; and
- diabetes mellitus.
For further information, refer to Australian Health Survey: Updated Results, 2011-12 [ABS Cat. no. 4364.0.55.003].
In addition to these, the NHS collects information on the following NHPA conditions:
- osteoporosis; and
- mental health.
NHS also collects information on other long-term conditions. Note that mental health conditions are collected within the long-term conditions module but have additional questions specific to NHPA conditions. In the NHPA conditions and kidney disease modules, respondents are specifically asked whether they have been diagnosed. Respondents are also asked whether the condition is current and long-term except where an assumption is made (e.g., cancers are considered to be long-term if they are identified as current). Each reported condition is then classified into the following categories:
- ever told has condition, still current and long-term;
- ever told has condition, still current but not long-term;
- ever told has condition, not current.
Respondents without a condition are classified into category 5: never told, not current or long-term. An additional category 4: ‘not known if ever told or not ever told, but condition current and long-term' is also used in the NHS where respondents are not asked about diagnosis. It is specifically used for sight and hearing conditions as well as any other long-term health conditions reported which had lasted, or were expected to last, for 6 months or more. Category 4 also applies to conditions in NHS where NHPA conditions or kidney disease were reported in the long-term conditions module and did not trigger a diagnosis question.
Condition prevalence is usually reported based on categories 1 and 4 (where applicable in NHS), i.e., that the condition is current and long-term. Current long-term conditions are defined as medical conditions (illnesses, injuries or disabilities) which were current at the time of the survey and which had lasted at least 6 months, or which the respondent expected to last for 6 months or more, including:
- long-term conditions from which only infrequent attacks may occur;
- long-term conditions which may be under control, for example, through the continuing use of medication;
- conditions which, although present, may not be generally considered ‘illness’ because they are not necessarily debilitating, e.g. reduced sight; and
- long-term or permanent impairments or disabilities.
In addition to the above conditions, NHS and NNPAS collects information on self-assessed health and female life stages, and NHS also collects information on disabilities and whether reported conditions (in conditions modules) were caused by injuries.
As the NNPAS only collected data for specific condition modules and required diagnosis, there was no opportunity to pick up conditions that may be recalled later in the survey through prompting, such as prompts used in the NHS long-term conditions module. Some differences in prevalence rates may therefore be apparent, particularly as reported NHS prevalence rates include conditions that are not identified as diagnosed but are long-term and current, whereas this population is not available in the production of NNPAS or core prevalence rates.
For full details, refer to the Australian Health Survey: Users' Guide, 2011-13 (ABS Cat. no. 4363.0.55.001).