4329.0.00.006 - Mortality of People Using Mental Health Services and Prescription Medications, Analysis of 2011 data  
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EXPLANATORY NOTES

INTRODUCTION

1 This publication contains statistics on characteristics and measures of mortality of persons who accessed Medicare Benefits Schedule (MBS) subsidised mental health-related services and/or Pharmaceutical Benefits Scheme (PBS) subsidised mental health-related prescription medications (‘mental health-related treatments’) in 2011. The cohort of persons who accessed mental health-related treatments during the calendar year 2011 was linked to death records for the 13-month period following the 2011 Census (between 10 August 2011 and 27 September 2012 inclusive).


DATA SOURCES

2 Data are sourced from the Mental Health Services-Census-Mortality Integrated Dataset which was created to enable analysis included in this publication. This dataset combines information about mental health-related data items from the MBS and PBS with information from the ABS Mortality, Enhanced Characteristics, Australia, 2011-12 dataset and 2011 Census of Population and Housing (Census).

Medicare Benefits Schedule and Pharmaceutical Benefits Scheme data

3 The Department of Human Services collects data on the activity of all persons making claims through the Medicare Benefits Scheme and provides this information to the Department of Health. Information collected includes the type of service provided (MBS item number) and the benefit paid by Medicare for the service. Item numbers and benefits paid by Medicare are based on the Medicare Benefits Schedule which is a listing of the Medicare services subsidised by the Australian Government. The Mental Health Services-Census-Mortality Integrated Dataset includes those MBS subsidised mental health-related services as defined in Appendix 1.

4 The Department of Human Services provides data on prescriptions funded through the Pharmaceutical Benefits Scheme to the Department of Health. The PBS lists all of the medicines available to be dispensed to patients at a Government-subsidised price. The Mental Health Services-Census-Mortality Integrated Dataset includes those PBS subsidised mental health-related prescription medications as defined in Appendix 2.

5 The scope of MBS and PBS data is restricted to persons who accessed subsidised mental health-related items listed on the MBS or PBS in 2011, and excludes:

  • persons who received services provided by hospital doctors to public patients in public hospitals, or services that qualify for a benefit under the Department of Veterans' Affairs National Treatment Account
  • the Repatriation Pharmaceutical Benefits Scheme which is subsidised by the Department of Veterans’ Affairs
  • persons who were supplied medications or accessed services through programs that do not use the Medicare processing system; for example, Aboriginal and Torres Strait Islander Health Programmes
  • persons accessing private prescription drugs, over the counter drugs, and drugs that cost less than the co-payment
  • persons who accessed MBS and/or PBS subsidised mental health-related treatments in 2011 but had a date of death before Census night 2011 (9 August).

2011 Census of Population and Housing

6 The 2011 Census measured the number and socio-demographic characteristics of people who were in Australia on Census night 2011 (9 August). The scope of the Census excludes:
  • persons whose Census record indicated they were an overseas visitor to Australia on Census night
  • persons usually resident in Australia who were out of the country on Census night
  • persons who were not enumerated in the 2011 Census.

7 For more detailed information about the 2011 Census refer to Census 2011 Reference and Information and Census Data Quality on the ABS website.

Mortality information

8 Mortality-related data items in the dataset were obtained from the ABS Mortality, Enhanced Characteristics, Australia, 2011-12 dataset, which combines deaths registrations with 2011 Census of Population and Housing.

9 Death registrations are provided to the ABS by state and territory Registrars of Births, Deaths and Marriages. As part of the registration process, information about the cause of death is supplied by a medical practitioner certifying the death, or by a coroner. Other information about the deceased is supplied by a relative or other person acquainted with the deceased or by an official of an institution where the death occurred. For deaths which are certified by a coroner, the ABS also receives information pertaining to cause of death from the National Coronial Information System (NCIS).

10 Deaths in scope of the dataset are those registered in Australia during the 13-month period following the 2011 Census; that is, between 10 August 2011 and 27 September 2012 inclusive. This reference period was selected in order to capture as many deaths as possible of people who were counted in the 2011 Census conducted on 9 August 2011.

11 For more detailed information about death registrations see Deaths, Australia (cat. no. 3302.0) and Causes of Death, Australia (cat. no. 3303.0).


METHOD USED TO CREATE THE MENTAL HEALTH SERVICES-CENSUS-MORTALITY INTEGRATED DATASET

12 The method used to create the Mental Health Services-Census-Mortality Integrated Dataset involved enhancing the existing Mental Health Services-Census Integrated Dataset through the addition of mortality information from the Mortality, Enhanced Characteristics, Australia, 2011-12 dataset, by merging these two source datasets according to an identifier common to both datasets as a result of each including Census data. The two source datasets were the result of previous, separate data integration projects: the former linking MBS and PBS information with 2011 Census and the latter linking mortality information with 2011 Census.

13 In creating the Mental Health-Census-Mortality Integrated Dataset some minor adjustments to the scope of the source datasets were required, resulting in small differences between data presented in this publication and data previously published from the source datasets:
  • a small number of records (34,534) of persons who accessed mental health-related treatments in 2011 were found to have had a date of death before Census night 2011 (9 August). These records were removed from the dataset
  • a small number of death registrations were recognised as being out of scope for linkage purposes for the Mortality, Enhanced Characteristics, Australia, 2011-12 dataset subsequent to the linkage process being undertaken. The total number of death registrations in the Mental Health-Census-Mortality Integrated Dataset (153,451 deaths) therefore differs sightly to that of the number in the Mortality, Enhanced Characteristics dataset (153,455 deaths).

14 For detailed information about the integration methods used for both source datasets see Characteristics of People Using Mental Health Services and Prescription Medication, 2011 (cat. no. 4329.0) and Mortality, Enhanced Characteristics, Australia, 2011-12 (cat. no. 3303.0.55.002).


WEIGHTING

15 Weighting is the process of adjusting a sample to infer results for the relevant population from which the sample has been taken. To do this, a 'weight' is allocated to each sample unit in a dataset. The weight can be considered an indication of how many people in the relevant population are represented by each person in the sample. In the case of data linkage projects, linked records can be considered to be the sample while all records (that is, linked and unlinked) comprise the relevant population.

16 Weighting also aims to compensate for differences in propensity to link, as some groups of records are more, or less, likely to link than other groups of records. This may result in over-representation of some groups and under-representation of others. Records are more difficult to link when a person has poorly reported, poorly coded, missing or non-applicable values for linking variables, such as date of birth, or place of usual residence.

17 Three weights were used to compile data in this publication, according to the particular population being reported upon:
  • ‘MBS/PBS weight’ – to calculate numbers of persons who accessed mental health-related treatments in 2011 (irrespective of whether a person had an associated death record in the 13 months following the 2011 Census)
  • ‘death registrations weight’ – to calculate numbers of deaths of persons in the period 10 August 2011 to 27 September 2012 inclusive (irrespective of whether a person had accessed mental health-related treatments in 2011)
  • ‘MBS/PBS/death registrations weight’ – to calculate numbers of deaths of persons (in the period 10 August 2011 to 27 September 2012 inclusive) who accessed mental health-related treatments in 2011.

18 The following section describes the populations included in the Mental Health Services-Census-Mortality Integrated Dataset as well as linkage rates and calculation of weights. The dataset includes 2,361,850 records in total (see Figure 1), comprising:
  • 2,276,632 records for persons who accessed mental health-related treatments in 2011 and which were linked to the 2011 Census, representing 3,190,847 persons in total who accessed mental health-related treatments in 2011 (a linkage rate of 71.3%)
  • 123,907 death registration records for the period 10 August 2011 to 27 September 2012 inclusive and which were linked to the 2011 Census, representing 153,451 death registrations in total for the same period (a linkage rate of 80.7%).

19 The two populations above include a subset of 38,689 records of persons who accessed mental health-related treatments in 2011 for whom a death registration was recorded for the period 10 August 2011 to 27 September 2012 inclusive.

Figure 1: Populations in Mental Health Services-Census-Morality Integrated Dataset


20 Weights for the two populations can be calculated as the multiplicative inverse of the linkage rate. To illustrate:
  • MBS/PBS weight - for all persons who accessed mental health-related treatments in 2011, the average weight is 3,190,847 / 2,276,632 = 1.40; that is, each of the 2,276,632 records for persons who accessed mental health-related treatments in 2011 in the dataset represents, on average, 1.40 persons
  • death registrations weight - for all death registrations in the period 10 August 2011 to 27 September 2012 inclusive, the average weight is 153,451 / 123,907 = 1.24; that is, each of the 123,907 death registration records in the dataset represents, on average, 1.24 death registrations.

21 MBS/PBS weights were benchmarked according to the following groups: sex, age group, state/territory, Remoteness Areas, type of treatment (as per Appendix 1 and Appendix 2) and death flag. These were the same as those used for the Mental Health Services-Census Integrated Dataset with the addition of the death flag which indicated those MBS/PBS records with an associated death notification for the period 10 August 2011 to 27 September 2012, as recorded on Medicare and provided by the Department of Human Services. Weights for different subgroups within the population of persons who accessed mental health-related treatments in 2011 differ as linkage rates vary between different subgroups (that is, different groups of persons were more, or less, likely to link to the 2011 Census than other groups).

22 Death registrations weights were benchmarked according to the following groups: sex, age group, state/territory, Remoteness Areas, Socio-economic Indexes for Areas and cause of death. These were the same as those used for the Mortality, Enhanced Characteristics, Australia, 2011-12 dataset. Weights for death registrations with different characteristics differ as linkage rates vary between death registrations (that is, death registrations with different characteristics were more, or less, likely to link to the 2011 Census).

23 The subset of 38,689 records of persons who accessed mental health-related treatments in 2011 for whom a death registration was recorded for the period 10 August 2011 to 27 September 2012 does not represent the total number of deaths of persons who accessed mental health-related treatments, as these records are subject to two sources of under-linkage: 1. that from linking records of persons who accessed mental health-related treatments in 2011 to the 2011 Census, and 2. that from linking death registrations to the 2011 Census.

24 To account for both sources of under-linkage to obtain the total number of death registrations of persons who accessed mental health-related treatments in 2011, weights (MBS/PBS/death registrations weight) for these records were calculated by multiplying both weights described above; that is, MBS/PBS weight * death registration weight. To illustrate:
  • for persons who accessed mental health-related treatments in 2011 for whom a death registration was recorded between 10 August 2011 and 27 September 2012, their average MBS/PBS weight was 1.59 while their average death registration weight was 1.24
  • the average weight for these records was therefore approximately 1.97 (that is, 1.24 * 1.59), noting that weights for these records also differ according to their different characteristics as some records were more, or less, likely to link to the 2011 Census than others
  • these 38,689 records therefore represent a total of 75,858 death registrations for persons who accessed mental health-related treatments in 2011.


DEATH RATES

25 Cause-specific death rates in this publication are presented as deaths per 100,000 population, while all other rates are presented as deaths per 1,000 population.

26 To allow comparisons between the population of persons who accessed mental health-related treatments in 2011 and the total Australian population, death rates have been age standardised to account for differences in the age structure of the two populations.


DATA QUALITY

27 All data collections are subject to sampling and non-sampling error. Non-sampling error may occur in any data collection. Possible sources of non-sampling error include errors in reporting or recording of information, occasional errors in coding and processing data, and errors introduced by linkage processes.

MBS data

28 MBS data includes Medicare-subsidised mental health-related services provided by psychiatrists, general practitioners (GPs), psychologists and other allied health professionals—including mental health nurses, occupational therapists, some social workers and Aboriginal health workers. These services are defined in the Medicare Benefits Schedule (see Appendix 1). In this publication, consultations with GPs refer to those that were recorded as mental health-related services. Consultations with GPs that may have involved discussion of mental health issues but were not recorded as mental-health related services were not captured in the Mental Health Services-Census Integrated Dataset.

29 Medicare data covers services that are provided out-of-hospital (for example, in doctors' consulting rooms) as well as in-hospital services provided to private patients whether they are treated in a private or public hospital. The figures do not include services provided to public patients in public hospitals or services that qualify for a benefit under the Department of Veterans Affairs National Treatment Account. States and territories are custodians of public hospital data [1].

PBS data

30 PBS data include subsidised prescription medication from the following groups: Antipsychotics, Anxiolytics, Hypnotics and Sedatives, Antidepressants, and Psychostimulants, agents used for ADHD and nootropics (see Appendix 2).

31 PBS data refer only to prescriptions scripted by registered medical practitioners who are approved to work within the PBS and to paid services processed from claims presented by approved pharmacists who comply with certain conditions. They exclude adjustments made against pharmacists’ claims, any manually paid claims or any benefits paid as a result of retrospective entitlement or refund of patient contributions [2].

32 PBS data exclude non-subsidised medications, such as private and over-the-counter medications. Under co-payment prescriptions (where the patient co-payment covers the total costs of the prescribed medication) data are available from mid-2012; and therefore not available for 2011 [2].

33 Data does not include the Repatriation Pharmaceutical Benefits Scheme (RPBS) which is subsidised by the Department of Veterans’ Affairs [3].

34 Data for Aboriginal and Torres Strait Islander Australians are not presented in this publication. The Aboriginal Health Services Program, funded by the PBS, does not use the Medicare PBS processing system [2]. Medications provided through this program are therefore not captured in the Mental Health Services-Census Integrated Dataset. Most affected are data for Remote and Very Remote areas and data for the Northern Territory.

Census of Population and Housing

35 The 2011 Census measured the number and key characteristics of people who were in Australia on Census night, 9 August 2011. For information about the 2011 Census please refer to Census 2011 Reference and Information and Census Data Quality on the ABS website.

Geography

36 Geographies used in linkage of the source datasets may not align between MBS and PBS and the Census, for a range of reasons, including:
  • differences arising because MBS and PBS Mesh Block are based on postal address whereas Census Mesh Block was based on address of usual residence
  • persons may have changed their address but not updated Medicare records.

37 Medicare claims data used in this dataset are based on the Mesh Block of the enrolment address of the patient. As clients may receive services in locations other than where they live, these data do not necessarily reflect the location in which services were received. Data therefore reflects geographic information about the recipient of mental health-related treatments, rather than where they received treatments.

Remoteness Areas

38 People living in Remote and Very Remote areas of Australia are under-represented in the data. This may be for a number of reasons including:
  • GPs are less likely to charge under Medicare in Remote areas [4].
  • non-metropolitan hospitals are more likely to admit patients, and people in Remote areas are more likely to attend hospital accident and emergency departments for primary care medical consultations than people from Major Cities [4]. People accessing these hospital services may be public inpatients and therefore not in scope. States and territories are the custodians for this data and it is not included in the dataset
  • in 2010-11, despite there being more GPs in Remote areas, there were about half the GP services provided per person in Very Remote areas as in Major Cities [5]
  • the Aboriginal Health Services Program is funded by the PBS however person-level data is not in the PBS processing system. Data from Remote and Very Remote areas, and the data from the Northern Territory are most affected [2]
  • Section 100 of the National Health Act, 1953 allows for the Minister to make special arrangements for the supply of medications to people living in isolated areas. These medications do not appear in the PBS data.

39 Numbers of deaths and death rates for Remote and Very Remote areas of Australia, as well as the Northern Territory, should be interpreted with caution due to under-representation of deaths amongst these populations.

40 The Census also undercounts the number of people living in some areas of Australia more than others. In 2011, the Northern Territory recorded the highest net undercount rate of all states and territories (6.9%) and showed the largest difference in the net undercount rate between its greater capital city and rest of state region (3.7% and 10.9% respectively) [6].


CLASSIFICATIONS

41 Classifications used in the Mental Health Services-Census-Mortality Integrated Dataset include:

International classification of diseases

42 Causes of death statistics are coded to the International Classification of Diseases 10th Revision (ICD-10). The ICD is the international standard classification for epidemiological purposes and is designed to promote international comparability in the collection, processing, classification, and presentation of causes of death statistics. The classification is used to classify diseases and causes of disease or injury as recorded on many types of medical records as well as death records. The ICD has been revised periodically to incorporate changes in the medical field.


ROUNDING

43 Estimates presented in this publication have been rounded. Proportions, rates and rate comparisons are calculated using unrounded estimates. Calculations using rounded estimates may differ from those published.


ACKNOWLEDGEMENT

44 The ABS acknowledges the continuing support provided by the National Mental Health Commission, the Department of Health, the Department of Human Services and state and territory Registrars of Births, Death and Marriages for this project. The provision of data by the Department of Health and the Department of Human Services as well as funding from the National Mental Health Commission was essential to enable this important work to be undertaken. The enhancement of mental health statistics through data linkage by the ABS would not be possible without their cooperation and support.

45 The ABS also acknowledges the importance of the information provided freely by individuals in the course of the 2011 Census. Census information provided by individuals to the ABS is treated in the strictest confidence as is required by the Census and Statistics Act (1905). MBS and PBS information provided by the Department of Health and the Department of Human Services to the ABS is treated in the strictest confidence as is required by the National Health Act (1953) and the Health Insurance Act (1973). Confidentiality of data on death registrations provided by state and territory Registrars of Births, Deaths and Marriages and the National Coronial Information System (NCIS) are protected by the Census and Statistics Act (1905) and the Privacy Act (1988).


ENDNOTES


[1] Department of Human Services, 2014, Medicare Item Reports, viewed 30 May 2016, <https://www.medicareaustralia.gov.au/statistics/mbs_item.shtml>

[2] Australian Institute of Health and Welfare, 2014, Medicare-subsidised mental health-related prescriptions, viewed 30 May 2016, <https://mhsa.aihw.gov.au/resources/prescriptions/>

[3] Department of Veterans' Affairs, 2014 Repatriation Pharmaceutical Benefits Scheme, viewed 30 May 2016, <http://www.dva.gov.au/about-dva/accountability-and-reporting/annual-reports/annual-reports-2012-13/department-veterans-12>

[4] Australian Institute of Health and Welfare, 2005, Rural, regional and remote health: Information framework and indicators, Rural Health Series Number 6, viewed 30 May 2016, <http://webarchive.nla.gov.au/gov/20170421134153/http://www.aihw.gov.au/publication-detail/?id=6442467780>

[5] Australian Institute of Health and Welfare, Jun 2014, Australia's Health 2014, Chapter 5: Health behaviours and other risks to health: Health in regional and remote areas, viewed 30 May 2016, <http://webarchive.nla.gov.au/gov/20170421065200/http://www.aihw.gov.au/publication-detail/?id=60129547205>

[6] Australian Bureau of Statistics, 2012, Estimates of Net Undercount, Census of Population and Housing - Details of Undercount, 2011, cat. no. 2940.0, viewed 30 May 2016, <https://www.abs.gov.au/ausstats/abs@.nsf/Products/2940.0~2011~Main+Features~Estimates+of+net+undercount?OpenDocument>