The National Prisoner Health Data Collection (NPHDC) contains data relating to people entering prison (prison entrants), people about to be released from prison (prison dischargees), clinic visits and services, and medications taken by prisoners. Data are collected over a 2-week period, and sent to the AIHW for collation, analysis and reporting.

The collection does not provide complete coverage of the prisoner population. Firstly, not all prisons are included because the collection has yet to achieve full participation by every jurisdiction in a single collection. Secondly, the collection is based on convenience sampling with prisoners approached for participation where possible, and not all of these prisoners providing consent.

The majority of the data collected for the entrants and dischargee sections are self-reported data. This method provides a simple and efficient method of collecting data. There are advantages to self-reported data such as it does not require specialised training for the interviewers, is often quicker than diagnostic interviewing (for health conditions), and provides the direct persepctive of the person being interviewed. The main disadvantage of self-reported data is that there is no independent validation of the responses. This may lead, for example, to deliberate under-reporting of illegal activities. Self-reported data may be compared with other self-reported data, but may not be directly comparable with reports and studies that use other data collection methods.

As a longer term aim, the data would ideally be collected as a by-product of jurisdictions' administrative systems, rather than being a separate data collection as it is currently. That would allow for the samples to be increased, thereby expanding the options for analysis, especially for entrants and dischargees data. It is anticipated that this would take time to achieve, because the data requirements for the NPHDC would need to be build into the administrative data systems in each jurisdiction.

The NPHDC is the only national source of infomration on the health of prisoners in Australia, covering a broad range of health issues and social and other determinants of health. The NPHDC is the main data source for the reporting of the National Prisoner Health Indicators. The complete set of indicators is listed in The health of Australia's prisoners report series, available from www.aihw.gov.au.

The Australian Institute of Health and Welfare (AIHW) is a major national agency set up by the Australian Government under the Australian Institute of Health and Welfare Act 1987 to provide reliable, regular and relevant information and statistics on Australia's health and welfare. It is an independent statutory authority established in 1987, governed by a management Board, and accountable to the Australian Parliament through the Health and Ageing portfolio.

The AIHW aims to improve the health and wellbeing of Australians through better health and welfare information and statistics. It collects and reports information on a wide range of topics and issues, ranging from health and welfare expenditure, hospitals, disease and injury, and mental health, to ageing, homelessness, disability and child protection.

The Institute also plays a role in developing and maintaining national metadata standards. This work contributes to improving the quality and consistency of national health and welfare statistics. The Institute works closely with governments and non-government organisations to achieve greater adherence to these standards in administrative data collections to promote national consistency and comparability of data and reporting.

One of the main functions of the AIHW is to work with the states and territories to improve the quality of administrative data and, where possible, to compile national datasets based on data from each jurisdiction, to analyse these datasets and disseminate information and statistics.

The Australian Institute of Health and Welfare Act 1987, in conjunction with compliance to the Privacy Act 1988 (Cth), ensures that the data collections managed by the AIHW are kept securely and under the strictest conditions with respect to privacy and confidentiality.

For further information see the AIHW website www.aihw.gov.au.

The AIHW has been maintaining the NPHDC since 2009.

The NPHDC has been collected 4 times: 2009, 2010, 2012 and 2015. The exact timing of the data collection and how often it will be conducted in the future are not yet confirmed. The 2015 report was released on 27 November 2015.

The AIHW website provides access to various prisoner health data reports including The health of Australia’s prisoners, and thematic bulletins, which can be downloaded free of charge. Users can request data not available online or in reports via the Child Welfare and Prisoner Health Unit, Australian Institute of Health and Welfare on (02) 6244 1000 or via email to [email protected]. A fee may be charged for substantial requests on a cost-recovery basis. General enquiries about AIHW publications can be made to the Digital and Media Communications Unit on (02) 6244 1032 or via email to [email protected].

Most of the data in the NPHDC are self-report rather than diagnostic health data. Reports such as The health of Australia’s prisoners have a ‘method’ section in the Introduction chapter, where technical information may be found. The metadata for  the collection are found in the Prisoner Health National Best Endeavours Data Set (METeOR identifier 482311) on the AIHW's Metadata Onling Registry (meteor.aihw.gov.au). METeOR is Australia's repository for national metadata standards for health, housing and community services statistics and information.

The denominator for indicators sourced from the clinic and medication data is the total number of prisoners in custody at 30 June for the relevant year. Some indicators in the NPHDC relate to 12 months of data (number of pregnant prisoners in custody, number of prisoners taking medication for hepatitis C, number of notifications of sexually transmitted infections). To provide an appropriate denominator for these indicators, jurisdictions provide data on the number of prisoners received into prison and released from prison, during the same 12-month period. This is a more appropriate denominator for these indicators, as it provides a more accurate representation of the number of prisoners over a 12-month period than the ABS 30 June snapshot, or an average daily number of prisoners, because the flow of prisoners through the system each year is up to 50% higher than the daily population.

Significance testing for the NPHDC is problematic because of the design and method of data collection. The collection is designed to be a census, capturing data on the entire population of interest. To date, this has not been achieved, as in practice some prisoners (especially prison entrants and dischargees) are not able to be approved for involvement in the data collection for various reasons. Of those who are, some do not provide consent to participate. The sample is therefore not probabilistic sampling, but rather convenience sampling, rendering standard approaches to statistical testing inappropriate. Comparisons in the report are therefore restricted to those where the data are both internally consistent with previous collections, and externally consistent with other similar data. There is a program of work being undertaken at the AIHW to develop a methodology to indicate variability of data points to support meaningful comparisons. The results of this work may inform future reports of the NPHDC. Incomplete coverage of all prisons and prisoners in the collection (see 'Coverage' below) also means that the data may not be representative of the whole prisoner population.

Scope and coverage

A prison entrant is classed as a person aged at least 18, entering full-time prison custody, either on remand (awaiting a trial or sentencing) or on a sentence. Prisoners who have been transferred from one prison to another are not included as entrants.

A prison dischargee is a full-time prisoner aged at least 18, who expects to be released from prison within the 4 weeks following the time of interview.

Prisoners aged at least 18 years, held in full-time custody in correctional facilities in Australia are in scope for the clinic and medication components of the NPHDC.

Police cells, court cells, periodic detention, juvenile correctional facilities and immigration detention centres are out of scope for all components of the NPHDC.

Reference period

The NPHDC was conducted over two 2-week periods, with some jurisdictions collecting data between 2-15 March 2015 and the remaining jurisdictions (excluding New South Wales) collecting data between 27 April-10 May 2015. In Queensland, the data collection was re-run in Arthur Gorrie, Townsville Male and Wolston Correctional Centres from 27 April to 10 May due to difficulties during the initial data collection round.

Entrants, dischargee and clinic data cover the whole 2-week period, and medications data cover 1 day in this 2 week period. Some indicators cover the entire 2014 year.

Coverage

Complete coverage of all prisons and prisoners has yet to be achieved in this data collection. The participation of jurisidictions and individual prisons has varied across the collection years for various reasons such as funding and resource availability and private prison contracts. A collection with full participation has not yet occurred. Not all eligible prisoners are able to be approached to participate, and some may not provide consent. For details on participation, see 'Participation rate' below.

In 2015, data were collected from all states and territories. In New South Wales, data were collected for selected entrants' data items only.

Statistical standards

Australian Standard Classification of Countries (ASCC) and Australian Standard Classification of Languages (ASCL) were used as the code frame for questions on country of birth and main language spoken at home.

Participation rate

Participation rates for entrants and dischargees have been calculated from data provided by the jurisdictions on the overall number of prisoners received into prison, and released from prison, during the 2-week data collection period. New South Wales were excluded from the calculations of participation rates because of methodological differences in their collection of entrants' data, and they did not provide dischargee data.

In Western Australia, Acacia Prison was unable to participate fully in the data collection due to resourcing constraints and was removed from the data.

For the entrant data, there were usable completed forms for 809 entrants from a total of 1,644 entrants into prisons during the 2-week period - a participation rate of 49%. Among dischargees, participation rates were calculated for all dischargees, and also for sentenced dischargees, who were the focus of data collection. During the data collection period, there were 445 usable dischargee forms completed, from a total of 1,740 prisoners discharged. Of those discharged, 1,059 were sentenced prisoners, resulting in a participation rate of 26% overall, with 42% among sentenced dischargees. The indicative participation rates among entrants and the target population group of sentenced dischargees were therefore similar.

Note that the method of calculation of participation rates has changed since 2012, so rates between 2012 and 2015 may not be comparable.

Indigenous data

Identification of Indigenous status was generally good in each state and territory, with unknown rates under 5%. The proportion of Indigenous participants in the entrants and discharge data were slightly higher than the reported proportion of the prisoner population on 30 June 2014.

The indicators that constitute the NPHDC were developed by the AIHW with the assistance and advice of the National Prisoner Health Information Committee (NPHIC) and are influenced by policy relevance in monitoring key aspects of prisoner health.

Where possible, existing data standards have been used, to increase comparability both within the NPHDC between collection years, and with other data collections such as those held by the ABS.

There have been some changes between collections in the NPHDC, with indicators being added and deleted, and some changes to definitions and data collection methods. For these reasons, caution should be used in making comparisons between different years of the collection.