Physical Inactivity
Physical inactivity is a major risk factor for a number of non-communicable diseases (NCDs). It refers to not meeting the recommended levels of physical activity for health. This document describes how physical inactivity is modeled, including the interventions considered and how the risk factor modifies disease incidence.
Used in
Physical inactivity is incorporated as a risk factor in the following disease models:
Mechanism
How does the risk factor modify incidence?
Physical inactivity increases the incidence of several NCDs. Incidence refers to the number of new cases of a disease occurring within a specified time period (usually a year). The model uses relative risk (RR) values to quantify this increased risk. These RR values are drawn from published scientific studies (specifically, a study by Peter T. Katzmarzyk, as indicated in the code comments).
Relative Risk (RR) Explained:
A relative risk of 1.0 means there's no difference in risk between two groups (e.g., active vs. inactive). An RR greater than 1.0 indicates an increased risk, while an RR less than 1.0 indicates a decreased risk.
The model applies the following RRs for physical inactivity:
- Ischemic Heart Disease (IHD): RR = 1.19. This means a physically inactive person is 1.19 times more likely to develop IHD than a physically active person. In percentage terms, this is a 19% increase in risk.
- Stroke: RR = 1.19 (same as IHD).
- Diabetes: RR = 1.17 (17% increase in risk).
How the Model Calculates Incidence Changes:
The model doesn't directly reduce the incidence rate. Instead, it works by reducing the prevalence of physical inactivity, which, in turn, indirectly reduces disease incidence. Here's a simplified breakdown of the process:
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Baseline Prevalence: The model starts with a baseline prevalence of physical inactivity in the population (for each age and sex group). This is the percentage of people considered physically inactive at the beginning of the simulation.
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Intervention Impact: The interventions (advice and awareness campaigns) are assumed to reduce this baseline prevalence. The code specifies the percentage reduction:
- Physical Activity Advice: Reduces the prevalence of physical inactivity by 15% of the people the intervention reaches
- Physical Activity Awareness: Reduces the prevalence of physical inactivity by 5% of the people who are reached by the campaign.
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Calculating the Population Attributable Fraction (PAF): After calculating the reduction in physical inactivity prevalence, the model recalculates the Population Attributable Fractions (PAFs) using the new, lower inactivity levels. The PAF represents how much of the disease burden can be attributed to physical inactivity. When inactivity decreases due to interventions, the PAF also decreases proportionally, which means less disease can be attributed to physical inactivity in the population.
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Intervention Impacts: The interventions reduce physical inactivity prevalence by specific amounts:
- Physical Activity Advice: Reduces prevalence by 15% among those reached
- Physical Activity Awareness: Reduces prevalence by 5% among those reached
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New Incidence: The reduced PAF, reflecting the lower prevalence of inactivity, is then used (in other parts of the model, not shown in the provided code snippet) to calculate the new, lower incidence rates for each disease. The new incidence rates would then be multiplied by population counts to generate new incidence numbers.
In Summary of Calculation
The interventions reduce the prevalence of physical inactivity. This reduction in the prevalence of the risk factor leads to a reduction in the Population Attributable Fraction (PAF), and the PAF reduction leads to a reduction in the incidence of the diseases associated with physical inactivity. The model essentially simulates a shift in the population's risk profile due to the interventions.
Interventions
Intervention Table
| Category | Code | Name |
|---|---|---|
| Physical inactivity | P1 | Provide physical activity assessment, counselling, and behaviour change support as part of routine primary health care services through the use of a brief intervention |
| Physical inactivity | P2 | Implement sustained, population wide, best practice communication campaigns to promote physical activity, with links to community-based programmes and environmental improvements to enable and support behaviour change |
| Physical inactivity | P3 | Implement urban and transport planning and urban design, at all levels of government, to provide compact neighbourhoods providing mixed-land use and connected networks for walking and cycling and equitable access to safe, quality public open spaces that enable and promote physical activity |
| Physical inactivity | P4 | Implement whole-of-school programmes that include quality physical education, and adequate facilities, equipment and programs supporting active travel to/from school and support physical activity for all children of all abilities during and after school |
| Physical inactivity | P5 | Improve walking and cycling infrastructure ensuring universal and equitable access to enable and promote walking, cycling, other forms of mobility involving the use of wheels (e.g. wheelchairs, scooters and skates) by people of all ages and abilities |
| Physical inactivity | P6 | Implement multi-component workplace physical activity programmes |
| Physical inactivity | P7 | Provide and promote physical activity through provision of community-based (grass roots) sport and recreation programmes and conduct free mass participation events to encourage engagement by people of all ages and abilities |
Null
| Intervention | Baseline | Target | Scale |
|---|---|---|---|
| Awareness campaigns to encourage physical activity | 10 | 0 | Scaled Down |
| Brief advice as part of routine care | 10 | 0 | Scaled Down |
P1
| Intervention | Baseline | Target | Scale |
|---|---|---|---|
| Awareness campaigns to encourage physical activity | 10 | 0 | Scaled Down |
| Brief advice as part of routine care | 10 | 95 | Scaled Up |
P2
| Intervention | Baseline | Target | Scale |
|---|---|---|---|
| Awareness campaigns to encourage physical activity | 10 | 95 | Scaled Up |
| Brief advice as part of routine care | 10 | 0 | Scaled Down |
Assumptions
Relative Risk
| Sex - Condition | 15 to 19 | 20 to 24 | 25 to 29 | 30 to 39 | 40 to 49 | 50 to 59 | 60 to 69 | 70 to 79 | 80 to 100 |
|---|---|---|---|---|---|---|---|---|---|
| Male - IHD | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 |
| Male - Stroke | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 |
| Male - Diabetes | 1.17 | 1.17 | 1.17 | 1.17 | 1.17 | 1.17 | 1.17 | 1.17 | 1.17 |
| Female - IHD | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 |
| Female - Stroke | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 | 1.19 |
| Female - Diabetes | 1.17 | 1.17 | 1.17 | 1.17 | 1.17 | 1.17 | 1.17 | 1.17 | 1.17 |
Prevalence Impact
| Intervention | Sex | 15-19 | 20-24 | 25-29 | 30-39 | 40-49 | 50-59 | 60-69 | 70-79 | 80-100 |
|---|---|---|---|---|---|---|---|---|---|---|
| Awareness campaigns to encourage increased physical activity | Male | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 |
| Female | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | |
| Brief advice as part of routine care | Male | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 |
| Female | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 |
Data Viewer
Below is a CSV viewer showing the physical inactivity data files used in this model:
No data to display.