Australian Institute of Health and Welfare (2020) Asthma, associated comorbidities and risk factors, AIHW, Australian Government, accessed 01 December 2022.
Australian Institute of Health and Welfare. (2020). Asthma, associated comorbidities and risk factors. Retrieved from https://www.aihw.gov.au/reports/chronic-respiratory-conditions/asthma-associated-comorbidities-risk-factors
Asthma, associated comorbidities and risk factors. Australian Institute of Health and Welfare, 25 August 2020, https://www.aihw.gov.au/reports/chronic-respiratory-conditions/asthma-associated-comorbidities-risk-factors
Australian Institute of Health and Welfare. Asthma, associated comorbidities and risk factors [Internet]. Canberra: Australian Institute of Health and Welfare, 2020 [cited 2022 Dec. 1]. Available from: https://www.aihw.gov.au/reports/chronic-respiratory-conditions/asthma-associated-comorbidities-risk-factors
Australian Institute of Health and Welfare (AIHW) 2020, Asthma, associated comorbidities and risk factors, viewed 1 December 2022, https://www.aihw.gov.au/reports/chronic-respiratory-conditions/asthma-associated-comorbidities-risk-factors
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Asthma shares a number of risk factors with other chronic conditions, such as:
Risk factors may increase the chance of developing asthma in the first place (either in childhood or as an adult), or may increase the chance that a person with asthma will develop additional health problems. Risk factors also vary according to the person's age, and according to the type of asthma that they have (AIHW 2019). Finding a factor that is associated with asthma, or poor health outcomes in asthma, does not necessarily mean that the risk factor caused these problems, or that they can be prevented.
In people with asthma, risk factors associated with an increased risk of flare-ups include (Global Initiative for Asthma 2019):
Based on the 2017–18 National Health Survey (NHS), people with asthma were more likely to be current daily smokers, insufficiently physically active and/or obese, compared with those without asthma (see Figure 1). Risk factor definitions are included in Box 1 (in the data notes section below). These risk factors are also common among other chronic conditions.
Note: Obese is based on body mass index (BMI) for persons whose height and weight was measured and imputed. In 2017–18, 33.8% of respondents aged 18 years and over did not have a measured BMI. For these respondents, imputation was used to obtain BMI. For more information, see Appendix 2: Physical measurements in the 2017–18 National Health Survey (ABS 2018a).
Source: ABS 2019a (Data table).
Compared with people without asthma, people with asthma were more likely to be current daily smokers (17% compared with 13% for people without asthma), and less likely to have never smoked (50% compared with 55% for people without asthma) (see Figure 2).
Tobacco use or exposure to environmental tobacco smoke are risk factors associated with the development of asthma. The interaction between exposure to tobacco smoke and development of asthma symptoms varies with age. Parental smoking during pregnancy or infancy is linked to asthma symptoms in children, and smoking by a parent or child/adolescent is linked to asthma symptoms in adolescence (Gilliland et al. 2006).
For people who already have asthma, smoking or exposure to environmental tobacco smoke can increase the risk of flare-ups and need for emergency care for asthma (Osborne et al. 2007). In people with asthma, smoking is also associated with a reduced effectiveness of inhaled corticosteroids (Lazarus et al. 2007; Tomlinson et al. 2005).
Sufficient physical activity (for example, regular exercise) is an important factor associated with positive health outcomes. Insufficient physical activity is a risk factor for several chronic conditions. It is also associated with overweight and obesity, and poorer health outcomes more generally. See Box 1 for definitions of physical activity.
Evidence suggests that sedentary behaviour (as measured by television viewing) is associated with asthma symptoms in children (Mitchell et al. 2012). The association between physical activity and asthma symptoms may be complicated by the fact that, in some people who already have asthma, physical activity may trigger asthma symptoms, particularly if their asthma is poorly controlled.
Physical activity is generally recommended for adults and children with asthma as a way to manage the disease and improve quality of life (National Asthma Council Australia 2019).
Based on the 2017–18 NHS, people with asthma were slightly less likely than people without asthma to engage in sufficient physical activity (42% compared with 46% for people without asthma) (Figure 3).
Source: ABS 2019a (Data table).
People with asthma were 1.4 times as likely to be obese (by measured body mass index or BMI—see Data notes) as people without asthma (42% with asthma compared with 30% without asthma) (Figure 4).
Studies show there are associations between overweight and obesity, as measured by BMI, and asthma, especially in high income countries (Beasley et al. 2015). Additionally, people with asthma who are overweight or obese often experience complications in treatment. For people who are overweight or obese, weight loss has been shown to reduce treatment complications and improve symptoms (Adeniyi & Young 2012; Juel et al. 2012). There is evidence of an association between being obese and developing asthma; however, the causative mechanisms between body mass and asthma are not currently well understood (Ford 2005; Kim et al. 2014).
Note: Based on body mass index (BMI) for persons whose height and weight was measured and imputed. In 2017–18, 33.8% of respondents aged 18 years and over did not have a measured BMI. For these respondents, imputation was used to obtain BMI. For more information, see Appendix 2: Physical measurements in the 2017–18 National Health Survey (ABS 2018a).
For people with asthma, the prevalence of risk factors varies by age.
The prevalence of smoking in people with asthma was higher in the earlier years of life. People aged 18–44 and 45–64 with asthma were more likely to be a current daily smoker (19% and 20%, respectively) compared with those aged 65 and over (7.6%) (Figure 5). Smoke free laws, tobacco price increases and greater exposure to mass media campaigns may contribute to lower smoking rates among older Australians (Wakefield et al. 2014). GPs play an important role in encouraging and supporting people to quit smoking, especially when they have health problems caused or exacerbated by smoking, which are more common with increasing age (Royal Australian College of General Practice 2014).
Among people with asthma, 50% of those aged 18–44 were insufficiently physically active, compared with 60% of those aged 45–64 and 76% of those aged 65 and over. Those aged 45-64 were less likely to be insufficiently physically active compared with those aged 65 and over. Among those with asthma aged 18–44, 35% were obese, compared with 48% of those aged 45–64 and 49% of those aged 65 and over (Figure 5).
This analysis is based on people aged 18 and over. This age group was selected due to the available data about risk factors in the ABS National Health Survey (NHS) and to ensure consistency with other AIHW risk factor reports (AIHW 2013; AIHW 2015).
The risk factor data presented here were obtained at one point in time, based on self‑reported data from the NHS (with the exception of BMI, which was measured). When interpreting self-reported data, it is important to recognise that it relies on respondents providing accurate information.
It is not possible to attribute cause and effect to self-reported (and measured) risk factors and asthma. Risk factors present at the time of the survey may or may not have contributed to the presence of asthma. Similarly, the presence of asthma may not be directly related to the number of risk factors a person has.
The risk factor definitions used in the ABS 2017–18 NHS are described below in Box 1.
Refers to the frequency of smoking of tobacco, including manufactured (packet) cigarettes, roll-your-own cigarettes, cigars and pipes, but excluding chewing tobacco, electronic cigarettes (and similar) and smoking of non-tobacco products. Categorised as:
Current daily smoker
A respondent who reported at the time of interview that they regularly smoked one or more cigarettes, cigars or pipes per day.
Current smoker – Other (occasional)
A respondent who reported at the time of interview that they smoked cigarettes, cigars or pipes, less frequently than daily.
A respondent who reported that they did not currently smoke, but had regularly smoked daily, or had smoked at least 100 cigarettes, or smoked pipes, cigars, etc at least 20 times in their lifetime; and
A respondent who reported they had never regularly smoked daily, and had smoked less than 100 cigarettes in their lifetime and had smoked pipes, cigars, etc less than 20 times.
Source: ABS 2018b.
Australia’s Physical Activity and Sedentary Behaviour Guidelines (the Guidelines) are a set of recommendations outlining the minimum levels of physical activity required for health benefits, as well as the maximum amount of time one should spend on sedentary behaviours to achieve optimal health outcomes (Department of Health 2019). Please see the Physical activity topic page for more information.
In 2017–18, the ABS National Health Survey collected information for the first time on physical activity at work. Therefore all results for adults include physical activity at work.
Based on the guidelines, insufficient physical activity is defined as:
For the purpose of calculating activity time, vigorous activity time is multiplied by a factor of two.
Muscle strengthening activities are not included in this analysis.
Source: AIHW 2019b.
Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, normal weight, overweight and obesity. It is calculated from height and weight information, using the formula weight (kg) divided by the square of height (m). To produce a measure of the prevalence of underweight, normal weight, overweight or obesity in adults, BMI values are grouped according to the table below.
Less than 18.50
25.00 — 29.99
30.00 — 34.99
Obesity class II
35.00 — 39.99
Obesity class III
40.00 or more
In 2017─18, 33.8% of respondents aged 18 years and over did not have a measured BMI. For these respondents, imputation was used to obtain BMI (ABS 2019b).
Sources: ABS 2018b; ABS 2019b.
ABS (Australian Bureau of Statistics) 2018a. National Health Survey: First Results, 2017–18. ABS Cat. no. 4364.0.55.001. Canberra: ABS.
ABS 2018b. National Health Survey: Glossary, 2017–18. Viewed 1 May 2019.
ABS 2019a. Microdata: National Health Survey, 2017–18, detailed microdata, Datalab. ABS cat no. 4324.0.55.001. Canberra: ABS. Findings based on AIHW analysis of ABS microdata.
ABS 2019b. National Health Survey: Users’ Guide, 2017–18. Viewed 5 June 2019.
Adeniyi FB & Young T 2012. Weight loss interventions for chronic asthma. Cochrane Database of Systematic Reviews (7):CD009339. doi:10.1002/14651858.CD009339.pub2.
AIHW (Australian Institute of Health and Welfare) 2013. Risk factors contributing to chronic disease. Cat. no. PHE 157. Canberra: AIHW.
AIHW 2015. Cardiovascular disease, diabetes and chronic kidney disease—Australian facts: risk factors. Cardiovascular, diabetes and chronic kidney disease series no. 4. Cat. no. CDK 4. Canberra: AIHW.
AIHW 2019. Insufficient physical inactivity: Web report. Canberra: AIHW. Viewed 1 May 2019.
Beasley R, Semprini A & Mitchel EA 2015. Risk factors for asthma: is prevention possible? Lancet 386:1075-85. doi: 10.1016/S0140-6736(15)00156-7.
Department of Health 2019. Australia's Physical Activity and Sedentary Behaviour Guidelines and the Australian 24-Hour Movement Guidelines. Canberra: Department of Health. Viewed 5 June 2019.
Ford ES. 2005. The epidemiology of obesity and asthma. Journal of Allergy and clinical Immunology 115(5): 897-909.
Gilliland FD, Islam T, Berhane K, Gauderman WJ, McConnel R, Avol E et al. 2006. Regular smoking and asthma incidence in adolescents. American Journal of Respiratory Critical Care Medicine 174:1094-100.
Global Initiative for Asthma (GINA) 2019. Pocket guide for asthma management and prevention (for adults and children older than 5 years). Viewed 1 May 2019.
Juel CT, Ali Z, Nilas L & Ulrik CS 2012. Asthma and obesity: does weight loss improve asthma control? A systematic review. Journal of Asthma and Allergy 5:21-26. doi: 10.2147/JAA.S32232.
Kim S, Sutherland ER & Gelfand EW 2014. Is there a link between obesity and asthma? Allergy, Asthma & Immunology Research 6(3): 189-195.
Lazarus SC, Chinchiili VM, Rollings NJ, Boushy HA, Cherniak R, Craig TJ et al. 2007. Smoking affects response to inhaled corticosteroids or leuktriene receptor antagonists in asthma. American Journal of Respiratory Critical Care Medicine 175(8):783-90.
Mitchell E, Beasely R, Bjorksten B, Crane J, Garcia-Marcos L, Keil U et al. 2012. The association between BMI vigorous physical activity and television viewing and the risk of symptoms of asthma, rhinoconjunctivitis and eczema in children and adolescents: ISAAC Phase Three. Clinical & Experimental Allergy (43) 73-84.
National Asthma Council Australia 2019. Australian Asthma Handbook, Version 2.0. Melbourne: National Asthma Council Australia. Viewed 1 May 2019.
Osborne ML, Pedula KL, O'Hollaren M, Ettinger K, Stibolt T, Buist AS et al. 2007. Assessing future need for acute care in adult asthmatics: the Profile of Asthma Risk Study: a prospective health maintenance organization-based study. Chest 132:1151-61.
Royal Australian College of General Practice (RACGP) 2014. Supporting smoking cessation: a guide for health professionals. Melbourne: The Royal Australian College of General Practitioners.
Tomlinson JE, McMahon AD, Chaudhuri R, Thompson JM, Wood SF, Thomson NC 2005. Efficacy of low and high dose inhaled corticosteroid in smokers versus non-smokers with mild asthma. Thorax 60(4):282-7.
Wakefield MA, Coomber K, Durkin SJ, Scollo M, Bayly M, Spittal MJ et al. 2014. Time series analysis of the impact of tobacco control policies on smoking prevalence among Australian adults, 2001–2011. Bulletin of the World Health Organization 92:413-22.
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