Limitations
The findings in this research are subject to certain limitations due to the data sources and methodology used, including:
- Self-harm index events were only identified from the admitted patient care dataset, therefore only capturing the severe cases and missing those presenting to ED who were not admitted. However, identification of self-harm cases in ED data is difficult (for more information see Intentional self-harm hospitalisations - AIHW).
- The self-harm index event was the individual’s first self-harm hospitalisation that appeared between 1 July 2011 and 30 June 2019, but this may not have always been the first self-harm hospital admission for that person, if they had been admitted for self-harm prior to this period.
- Our estimates of health service use do not include non-Government funded health services (such as by private insurance, through workers compensation arrangements, or the individual), or services funded by Defence or Open Arms. As such, use of health services is likely an underestimate in this report.
- ED care and hospital admitted patient care were analysed separately, and overlapping admissions were not excluded. This should be considered when interpreting the results. Where ex-serving members have overlapping admissions then this could lead to an overestimate of health service use.
- There are difficulties in determining the presence of intent that may cause an underestimate of admissions that should be classified under intentional self-harm.
- Matched cohort studies are an observational study design, and can identify associations between health service use and intentional self-harm but cannot establish causality.
- Comparisons of health service by ex-serving members who were admitted for self-harm using OR and RR accounted for demographics and adjusted for comorbidities. Other relevant factors (such as service or service length) were examined in subgroup analyses, but not included in adjusted models, so a degree of residual confounding is likely to remain.
- The services that Medicare subsidises, and how similar services are coded has changed over time, particularly for mental health services provided by GPs and allied health professionals which can impact analysis of trends over time.
- Prior to 1 April 2012, the PBS/RPBS claims data did not collect data on under co-payment medications (medications that were not Government subsidised because they were priced under the co-payment threshold). Caution should be used when comparing data prior and after this period.
- The PBS/RPBS data does not include medicines supplied to public hospital in-patients, over the counter medicines or private prescriptions.
- There are differences between MBS services and DVA-funded MBS equivalent services. For example, DVA clients may be eligible to higher or ‘uncapped’ services than through MBS. DVA has also increased access to mental health services through various policy changes since 2001, most significantly in 2016 when eligibility was expanded to include all current and former ADF members with at least one day of continuous full-time service.
- DVA-funded MBS equivalent services were not included in the latent class analysis and the transition analysis. Their exclusion may lead to underestimation of service use among DVA clients.
- There are multiple limitations that apply which relate to mental health analysis:
- Community mental health care services were not included in this report. These services often treat mental health conditions in specialised community and hospital-based outpatient psychiatric services provided by state and territory governments.
- Mental health items could be miscoded or reported, for example, many GP mental health services are billed under general GP consultations (Medicare mental health services - Mental health).
- Mental health-related ED presentations refer to presentations that have a principal diagnosis that falls within the Mental and behavioural disorders chapter (Chapter 5) of ICD‑10‑AM (codes F00–F99). It should be noted that this definition does not encompass all mental health‑related presentations to ED (see Emergency departments - Mental health).
- Mental health admitted care is defined by a principal diagnosis in the Mental and behavioural disorders chapter. ‘Any mental health admitted care’ is defined by a principal or secondary diagnosis in the Mental and behavioural disorders chapter. It should be noted that this definition does not include all mental health-related admitted care (see Characteristics of ex-serving Australian Defence Force members hospitalised for suicidality and intentional self-harm).
- Analysis presented by separation reason only contains ex-serving ADF members who separated from 1 January 2003 onwards because of changes to the way the reason for separating the ADF was recorded in 2002.