Multimorbidity in Australia

Chronic conditions can occur together in an individual because they:

• are common – conditions that are more common are more likely to occur together than rare conditions
• share common risk factors or one condition is a risk factor for another
• are commonly diagnosed together – for example where screening tests are designed to identify multiple conditions.

These factors influence the patterns of multimorbidity. For more information, see Factors contributing to multimorbidity in the section Variation by condition group.

Patterns of multimorbidity on this page are identified through analysis of conditions that commonly occur together (co-occurring conditions), and conditions that are common among people with a specific condition of interest (common comorbidities).

Understanding which conditions commonly occur together can help identify associations between conditions and could be used to inform approaches to management and treatment.

Co-occurring conditions

In 2022, anxiety, back problems and depression were the most common of the selected long-term health conditions (AIHW 2024). These conditions feature among the most common co-occurring conditions among people of all ages in 2022 with:

• anxiety and depression affecting an estimated 2.4 million people (9.3%)
• anxiety and back problems affecting an estimated 1.3 million people (5.3%)
• back problems and depression affecting an estimated 1.0 million people (4.0%) (Figure 8).

Variation by age and sex

In 2022, the most commonly co-occurring long-term health conditions varied by age and sex (Figure 9).

While depression and anxiety co-occur prominently across all age groups, long-term health conditions most commonly diagnosed in childhood (such as ADHD and autism) tend to feature in multimorbidity among younger age groups.

In contrast, conditions that develop over the life-course (such as back problems, osteoarthritis and deafness or hearing loss) feature more with increasing age.

In 2022, an estimated 4.8 million people (19%) were living with anxiety (Data table MM03). Anxiety commonly occurred together with other conditions among people aged under 65. For example, anxiety and depression were estimated to co-occur among:

• 197,000 males (4.9%) and 323,000 females (8.5%) aged 0–24
• 311,000 males (8.7%) and 483,000 females (13%) aged 25–44
• 331,000 males (11%) and 367,000 females (12%) aged 45–64 (Figure 9).

An estimated 4.0 million people (16%) were living with back problems (including sciatica, disc disorders and curvature of the spine) in 2022 (Data table MM03). Back problems commonly occurred with other conditions among people aged 45–64 and those aged 65 and over. For example, in 2022 an estimated:

• 169,000 males aged 45–64 (5.6%) and 289,000 males aged 65 and over (15%) were living with back problems and deafness or hearing loss
• 173,000 females aged 45–64 (5.5%) and 272,000 females aged 65 and over (12%) were living with back problems and osteoarthritis (Figure 9).

Common comorbidities

A ‘comorbidity’ refers to an additional condition experienced by a person who has a specific condition of interest.

The most common comorbidities differ among individuals with different conditions.

For example, Figure 10 shows that in 2022, based on self-reported information an estimated:

• 32% of people living with asthma were also living with anxiety – this is higher than the proportion of Australian’s of all ages living with anxiety (19%) (Data table MM03)
• 43% of people with COPD were also living with asthma – evidence suggests asthma is a risk factor for developing COPD (GOLD 2025).

Use the drop-down list in Figure 10 to select conditions and view their 10 most common associated comorbidities.

The prevalence of comorbid conditions also varies between the selected conditions.

For example, based on self-reported information, in 2022 type 2 diabetes was a common comorbidity among people of all ages with:

• coronary heart disease (CHD) – an estimated 25% of people with CHD were living with diabetes
• heart failure – an estimated 24% of people with heart failure were living with diabetes
• chronic kidney disease (CKD) – an estimated 24% of people with chronic kidney disease were living with diabetes (Figure 11).

In contrast, 13% of people with osteoarthritis were also living with diabetes.

CHD, heart failure and CKD have known associations with diabetes and between each other. For more information, including on the prevalence of comorbid cardiovascular disease, diabetes and chronic kidney disease based on biomedical data, see Comorbidity of heart, stroke and vascular disease.

Figure 11 allows you to select a comorbidity and view the 10 conditions it most commonly occurs with.