4329.0.00.004 - National Health Survey: Mental Health and co-existing physical health conditions, Australia, 2014 - 15  
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INTRODUCTION

Comorbidity is the presence of two or more disorders (or diseases) in one person at the same time1. It is common among people with a mental and behavioural condition, with almost all people (94.1%) with a mental and behavioural condition reporting another co-existing long-term health condition. Mental health comorbidity can occur when someone with a mental and behavioural condition has:
    • At least one co-existing physical health condition; and/or
    • More than one mental and behavioural condition.

Comorbidity is often associated with worse health outcomes, more complex clinical management and increased health care costs2. Often, people with comorbidity experience diminished quality of life, especially as the number of co-existing conditions increases3. Therefore, reporting on comorbidity and gaining a better understanding around the characteristics of people with co-existing health conditions is essential in order for the effective prevention, treatment and management of people’s health.

This publication presents information from the 2014-15 National Health Survey (NHS) which was designed to obtain national benchmarks on a wide range of health issues, including the health status of the population, health risk factors (such as smoking and obesity) and health service use. Comorbidity in this publication refers to people with more than one long-term health condition, where those conditions are current and have lasted, or are expected to last, for six months or more. Mental and behavioural conditions in this publication are those described in Appendix 1: Explanatory Notes, and include both diagnosed and undiagnosed cases. All other conditions are being treated as 'physical health conditions'.

While the majority of tables in this publication include both conditions related to mortality (that is, conditions associated with a person’s leading cause of death as reported in Causes of Death, Australia, 2013) and those that may be associated with decreased quality of life, tables 11 to 13 present comorbidity data in terms of co-existing physical health conditions associated with mortality only.



COMORBIDITY GROUPS

In 2014-15, four in every five Australians (79.7%) reported having at least one long-term mental, behavioural or physical health condition, with the remaining one in five Australians (20.3%) reporting no long-term health conditions.

In terms of mental health and comorbidity, 15.8% of all Australians (3.6 million people) reported co-existing long-term mental and behavioural and physical health conditions. This included:

    • 13.3% of the population who had at least one mental and behavioural condition and two or more physical health conditions; and
    • 2.5% who had at least one mental and behavioural condition and only one co-existing physical health condition.

Those who reported two or more mental and behavioural conditions only (and no co-existing physical health conditions) made up 0.6% of the population, while those with one mental and behavioural condition only (and no co-existing physical health conditions) accounted for 1% of the population - see Figure 1. This highlights the importance of reporting on mental health and comorbidity given the overwhelming prevalence of co-existing conditions amongst people with a mental and behavioural condition.

Figure 1: Co-existing health condition status flow-chart



Graphic: Co-existing health condition status flow-chart


Overall, people with a long-term mental and behavioural condition were more likely to have a co-existing physical health condition compared with people without a mental and behavioural condition. Of all reported long-term physical health conditions, mental and behavioural conditions were most likely to co-exist with long and short sightedness (36.5% and 29.8% respectively) back problems (27.7%), arthritis (23.9%) and hayfever and allergic rhinitis (22.6%), matching the most common physical health conditions reported amongst the general population.

People with a mental and behavioural condition were almost twice as likely than those without a mental and behavioural condition to report having diabetes (8.1% compared with 4.5%), almost three times as likely to report chronic obstructive pulmonary disease (COPD) (5.7% compared with 2.0%) and around twice as likely to report osteoporosis (6.3% compared with 2.9%).


Graph Image for People with selected long-term physical health conditions(b) by Mental and Behavioural condition status, 2014-15

Footnote(s): (a) Includes organic mental problems, alcohol and drug problems, mood (affective) disorders, anxiety related disorders and other mental and behavioural problems. Data for 2014-15 are not comparable to earlier years due to a change in collection methodology. (b) Persons who have a current medical condition which has lasted, or is expected to last, for 6 months or more. (c) Includes rheumatoid arthritis, osteoarthritis, other and type unknown. (d) Includes sciatica, disc disorders, back pain/problems not elsewhere classified and curvature of the spine. (e) Includes bronchitis and emphysema. (f) Includes complete deafness, partial deafness and hearing loss not elsewhere classified. (g) Includes Type 1 and Type 2 diabetes, and type unknown. Estimates include persons who reported they had diabetes but that it was not current at the time of interview. (h) Includes angina, heart attack, other ischaemic heart diseases, stroke, other cerebrovascular diseases, oedema, heart failure, and diseases of the arteries, arterioles and capillaries. Estimates include persons who reported they had angina, heart attack, other ischaemic heart diseases, stroke or other cerebrovascular diseases but that these conditions were not current at the time of interview. These persons were excluded from previous estimates of heart, stroke and vascular disease published in Australian Health Survey: First Results, 2011-12 (cat. no. 4364.0.55.001) and Australian Health Survey: Updated Results, 2011-12 (cat. no. 4364.0.55.003).

Source(s): National Health Survey, 2014-15




Overall in 2014-15, more females than males had co-existing long-term mental and behavioural and physical health conditions (17.7% compared with 13.9% respectively). However, this did vary depending upon the condition. Males were more likely to have a long-term mental and behavioural condition co-existing with deafness and hypertensive disease (21.4% and 18.5% compared with 12.5% and 12.9% of females), while females were more likely than males to have arthritis (26.7% compared with 20.5%).

The prevalence of co-existing mental and physical health conditions generally increased with age up to the 55-64 year age group. Around two in ten people aged 35-64 years reported having a mental and behavioural condition along with at least one co-existing physical health condition. This compared with around one in ten people aged 0-24 years.


Graph Image for People with a mental and behavioural, and physical health condition(a) by Age group, 2014-15

Footnote(s): (a) May have more than one mental and behavioural, and physical condition.

Source(s): National Health Survey, 2014-15





SOCIO-DEMOGRAPHIC CHARACTERISTICS

People with co-existing mental and physical health conditions were more likely to be unemployed, have a lower level of educational attainment, and be living in a lone-person household compared with those with physical health conditions only.

Of all people aged 15-64 years with co-existing mental and behavioural and physical health conditions, 8.6% were unemployed, compared with 3.2% of people with a physical health condition only.


Graph Image for People 15-64 years who were unemployed by Comorbid population group, 2014-15

Footnote(s): a) May have more than one mental and behavioural, and physical condition.

Source(s): National Health Survey, 2014-15




People aged 15 years and over with co-existing mental and behavioural and physical health conditions were less likely to have a non-school qualification compared with people with physical health conditions only. Two in ten people (20.5%) with a mental and behavioural condition and co-existing physical health condition had obtained a bachelor degree or above compared with almost three in ten people (28.1%) with one or more physical health conditions only.

In particular, people with arthritis and a co-existing mental and behavioural condition were less likely to have a bachelor degree or above compared with people with arthritis but without a mental and behavioural condition (12.1% compared with 18.1% respectively).

The most common household structures differed for people depending on their co-existing health condition status. Overall, those with co-existing mental and behavioural and physical health conditions were more likely to be living alone or in a single parent household (16.2% and 12.4%) compared with people with physical health conditions only (12.1% and 8.6% respectively).

In addition, the most common household structures differed for those with a mental and behavioural condition and one co-existing physical health condition compared with those with two or more co-existing physical health conditions. People with a mental and behavioural condition and one co-existing physical health condition were more likely to live alone than people with a mental and behavioural condition and two co-existing physical health conditions (17.6% and 9.4% respectively).

Graph Image for People living in various household structures, by mental and behavioural, and physical comorbidity, 2014-15

Source(s): National Health Survey, 2014-15



People who reported a mental and behavioural condition were more likely to be born in Australia and speak English as their main language at home, compared with people with physical health conditions only. This was true regardless of whether they had a mental and behavioural condition only or whether they also had a co-existing physical health condition. People with a mental and behavioural condition were also more likely to have a disability compared with people with physical health conditions only.

People with co-existing mental and behavioural and physical health conditions, or two or more mental and behavioural conditions only were more likely than people with physical health conditions only or no long-term health conditions to have provided unpaid care, help or assistance to someone in the last 4 weeks, with 20.9% reporting carer duties, compared with 16.9% and 7.0% respectively.



MENTAL AND BEHAVIOURAL CONDITIONS AND NUMBER OF CO-EXISTING PHYSICAL HEALTH CONDITIONS

For people with a mental and behavioural condition, as the number of co-existing physical conditions increases, so too does the likelihood that they will live in a more disadvantaged area.

Of people who reported a mental and behavioural condition and five or more co-existing physical health conditions, three in ten (30.3%) were living in areas of most disadvantage across Australia compared with two in ten people (20.6%) who reported two co-existing physical health conditions and less than two in ten people (17.2%) with one or more mental and behavioural conditions only (that is, with no co-existing physical health conditions).

People aged 15-64 years with a mental and behavioural condition and five or more co-existing physical health conditions were less likely to be in the labour force, with four in ten people (41.1%) not in the labour force, compared with two in ten people (20.7%) with a mental and behavioural condition and only one co-existing physical health condition.

Although for people with mental and behavioural conditions the overall likelihood of disability increased with the number of co-existing physical health conditions, the prevalence of profound or severe core activity limitation (those who required help or supervision for one or more core activities, such as self-care, mobility or communication) remained relatively stable for those with up to four co-existing physical health conditions (ranging from 7.1% to 9.1%). In contrast, people with a mental and behavioural condition and five or more co-existing physical health conditions were more than twice as likely to have a profound or severe disability (21.3%).

While not associated with poorer socio-demographic outcomes, people with a mental and behavioural condition and multiple co-existing physical health conditions were also more likely to be living alone. Those with a mental and behavioural condition and three or more co-existing physical health conditions were around three times more likely than people with one or more mental and behavioural conditions only (that is, with no co-existing physical health conditions) to be living alone.



MENTAL AND PHYSICAL COMORBIDITY

While the causal relationship between co-existing conditions cannot be determined in this dataset, for people with mental and behavioural and physical health comorbidity, long-term physical health conditions were more likely to co-exist with specific mental and behavioural conditions.

In 2014-15, 9.3% of the Australian population reported a mood (affective) problem, which includes depression. For people with co-existing physical health conditions, those with COPD were almost three times as likely as the general population to report a mood affective problem (26.3%). Similarly; people with osteoporosis and those with diabetes were twice as likely as the general population to report a mood (affective) problem (20.0% and 19.1%, respectively).

Overall, just over one in every ten Australians (11.2%) reported an anxiety related disorder in 2014-15. As with mood (affective) problems, of all reported physical health conditions those with COPD were most likely to have a co-existing anxiety-related disorder (25.2%) followed by people with osteoporosis (22.7%).

In particular, people with COPD were most likely to have reported a co-existing obsessive-compulsive disorder (5.6% compared with 1.2% of the general population), while people with osteoporosis were more likely than the general population to have reported co-existing panic disorders/panic attacks (8.2% compared with 2.5%).



CO-EXISTING MENTAL AND BEHAVIOURAL CONDITIONS

In addition to co-existing mental and behavioural and physical health conditions, comorbidity can occur when two or more mental and behavioural conditions co-exist.

In 2014-15, 1.8 million people (8.8% of females and 6.5% of males) had two or more mental and behavioural conditions, including people who also had a co-existing physical health condition, while 0.6% of the population (144,800) had two or more mental and behavioural conditions only (that is, no co-existing physical health condition).

The most commonly co-existing mental and behavioural conditions were anxiety (which includes feeling anxious, nervous or tense) and depression (which includes feeling depressed) with just over one million people (4.4%) experiencing both conditions. There were a number of conditions which, although less prevalent, were more likely to be present in conjunction with another mental and behavioural condition. For example, for eight out of ten people, anxiety was reported as co-existing with panic disorders/panic attacks while seven out of every ten people with post-traumatic stress disorder (PTSD) also experienced depression.

Almost two in ten people with phobic anxiety disorders (18.9%) also reported obsessive-compulsive disorder, and over three in ten people with problems of psychological development (36.0%) reported feeling anxious, nervous or tense (the most common co-existing mental and behavioural condition for this group).

People with two or more mental and behavioural conditions only (that is no co-existing physical health conditions) were less likely than people with co-existing mental and behavioural and physical health conditions to be living alone (8.6% compared with 16.2%).

In terms of educational attainment, people with comorbidity including a mental and behavioural condition were less likely than people with one or more physical health conditions only to have a bachelor degree or above. Almost three in ten people (28.1%) with one or more physical health conditions only had a bachelor degree or above, compared with two in ten people (20.5%) with a mental and behavioural condition and co-existing physical health condition and around one in ten people (8.3%) with two or more mental and behavioural conditions only.


Graph Image for People 15 years and over with Bachelor degree or above by Comorbid population group, 2014-15

Source(s): National Health Survey, 2014-15





COMORBIDITY AND HEALTH RISK FACTORS

Examining information on health risk factors and behaviours can enable a better understanding of the future health needs of Australia's population. Specific lifestyle and related factors which have been identified as negatively impacting health include being overweight or obese, smoking, excessive alcohol consumption, poor diet and nutrition, and lack of physical activity.

Of people aged 18 years and over with co-existing mental and behavioural and physical health conditions, almost three-quarters (72.8%) reported no or low levels of exercise. This compared with around two-thirds (67.8%) of adults with one mental and behavioural condition only and 65.6% of adults with one or more physical health conditions only.

While overall, males were more likely to be overweight or obese than females (70.8% compared with 56.3% respectively), people with co-existing mental and behavioural and physical health conditions were more likely to be overweight or obese (65.2%), compared with people with one mental and behavioural condition only (46.8%).

In addition, those with a mental and behavioural condition and two or more physical health conditions were more likely to be overweight or obese than those with a mental and behavioural condition and just one co-existing physical health condition (67.2% compared with 50.6% respectively).


Graph Image for People 18 years and over who were obese or overweight by Comorbid population group and Sex, 2014-15

Source(s): National Health Survey, 2014-15




Across all reported population groups, men were more likely to smoke compared with women (18.9% of men were current smokers compared with 13.3% of women). Adults with mental and behavioural conditions, regardless of whether they had a co-existing physical health condition were more likely to be current smokers compared with people with physical health conditions only, or no health conditions.

As with smoking, men were also more likely to consume alcohol at risky levels compared with women. Almost six in ten people with one or more mental and behavioural conditions only exceeded 2009 National Health and Medical Research Council single occasion risk guidelines compared with just over four in ten people with co-existing mental and behavioural and physical health conditions or a physical health condition only.


Graph Image for People 18 years and over who exceeded alcohol consumption guidelines by Comorbid population groups, 2014-15

Source(s): National Health Survey, 2014-15




COMORBIDITY AND WELLBEING

The Kessler Psychological Distress Scale (K10) measures a person's psychological distress levels based on questions about their level of nervousness, agitation, psychological fatigue and depression in the past four weeks, and provides an indication of the mental health and wellbeing of a population.

Overall in 2014-15, 11.7% of Australian adults experienced high or very high levels of psychological distress according to the K10. People with two or more mental and behavioural conditions only were 5 times as likely as the general adult population to report high or very high levels of psychological distress (55.9%). Similarly those with co-existing mental and behavioural and physical health conditions were almost four times as likely (40.9%) to report high or very high levels of psychological distress as the general adult population. In contrast, just 3.8% of people who reported no conditions and 5.0% of people who reported one or more physical health conditions only experienced high or very high distress levels.

An increase in the number of co-existing physical health conditions did not correlate with an increase in distress levels for people with a co-existing mental and behavioural condition.


Graph Image for People 18 years and over with high or very high psychological distress levels by Comorbidity population groups, 2014-15

Source(s): National Health Survey, 2014-15





COMORBIDITY AND HEALTH SERVICE USE

A variety of health actions and services are available for people to maintain, manage and/or improve their health, including seeking advice on treatment or prevention mechanisms from health professionals. Overall in 2014-15, females consistently undertook more actions for their health compared with men.

Around seven in ten people (72.3%) with co-existing mental and behavioural and physical health conditions had last consulted a GP for their own health in the preceding three months. This compared with just over half of all people with one or more physical health conditions only (55.7%), and 43.7% of people with one mental and behavioural condition only. People with co-existing mental and behavioural and physical health conditions, and those with two or more mental and behavioural conditions only were also most likely of all the population groups to have consulted a specialist, with over half having consulted a specialist in the last 12 months.

People with co-existing mental and behavioural and physical health conditions were most likely to undertake health examinations and screening compared with other population groups. Of people with a mental and behavioural and co-existing physical health condition, 63.4% reported regularly checking their skin for changes in freckles and moles, compared with 57.7% of people with one or more physical health conditions only.

In terms of being tested for various cancer types, more than half (53.8%) of people with a mental and behavioural and co-existing physical health condition reported they had been tested for any type of cancer in the last two years. This compared with 47.7% of people with one or more physical health conditions only, and 21.2% of people with no reported long-term health conditions.

While people with comorbidity including a mental and behavioural condition were more likely to use health services than people with physical health conditions only, they were less likely to have private health insurance. Six out of every ten people (60.9%) with one or more physical health conditions only reported having private health insurance, compared with around five in ten people (48.9%) with co-existing mental and behavioural and physical health conditions, and three in ten people (33.4%) with two or more mental and behavioural conditions only.



COMORBIDITY AND MORTALITY-RELATED PHYSICAL HEALTH CONDITIONS

As outlined in the introduction of this publication, Tables 11, 12 and 13 present comorbidity data in terms of mental and behavioural conditions and co-existing physical health conditions associated with mortality only. That is, these tables include mental and behavioural conditions and only physical conditions which have been associated with a person's leading cause of death (as reported in Causes of Death, Australia 2013), such as heart, stroke and vascular disease or diabetes. Comparison tables where physical conditions relating to mortality as well as those not related to mortality however associated with decreased quality of life have been included (such as sight problems or hayfever and allergic rhinitis) are tables 3, 5 and 7. The following analysis outlines a few characteristics of the people with co-existing mental and behavioural and mortality-related physical health conditions.

Overall in 2014-15, more females than males had co-existing long-term mental and behavioural and mortality-related physical health conditions (15.6% compared with 12.0% respectively). Compared with analysis including all physical health conditions, the prevalence of co-existing mental and behavioural and mortality-related physical health conditions remained fairly similar for older age groups, however decreased slightly amongst younger age groups. This is consistent with the general finding that the prevalence of many conditions associated with mortality increases with age.

In terms of health risk factors (such as smoking and obesity) analysing comorbidity with mortality-related physical health conditions appeared to have little effect on the patterns of risk amongst the co-existing health condition status groups. Adults reporting two or more mental and behavioural conditions only (and no mortality-related physical health conditions) were still most likely of all the groups to be smokers and along with the group reporting one or more mortality-related physical conditions only, less likely than other groups to report no or low levels of exercise.



ENDNOTES

1 L. Degenhardt, W. Hall, M. Lynskey, 2003, “What is comorbidity and why does it occur?”, Comorbid mental disorders and substance use disorders: epidemiology, prevention and treatment, pp. 10-25, <http://www.health.gov.au/internet/main/publishing.nsf/Content/B42C804645A11AAECA257BF0001E7283/$File/ch2.pdf>.

2 J. M. Valderas, B. Starfield, B. Sibbald, C. Salisbury, M. Roland, July 2009, “Defining Comorbidity: Implications for Understanding Health and Health Services”, Annals of Family Medicine, Vol. 7:4, pp. 357-363, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2713155/>.

3 J. Xuan, L.J. Kirchdoerfer, J.G. Boyer, G.J. Norwood, Feb 1999, “Effects of comorbidity on health-related quality-of-life scores: an analysis of clinical trial data”, Clinical Therapeutics, Vol. 21:2, pp. 383-403, <http://www.ncbi.nlm.nih.gov/pubmed/10211540?report=abstract>.