4364.0.55.005 - Australian Health Survey: Biomedical Results for Chronic Diseases, 2011-12  
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Contents >> Cardiovascular disease >> Cholesterol


CHOLESTEROL

Cholesterol is a type of fat that circulates in the blood. It is essential for many metabolic processes, including the production of hormones and building cells. There are two main types of cholesterol: high density lipoprotein (HDL) and low density lipoprotein (LDL). HDL cholesterol is known as 'good' cholesterol, as it picks up excess cholesterol in the blood and takes it to the liver where it is broken down, helping to prevent blockages. Low levels of HDL may increase the risk of heart disease. LDL cholesterol, on the other hand, is known as 'bad' cholesterol, as high levels in the bloodstream can lead to fatty deposits developing in the arteries, increasing the risk of heart attack or stroke.

    Data source and definitions

    Cholesterol levels are measured using a blood test. Abnormal cholesterol levels are defined as follows:
    • Total cholesterol greater than or equal to 5.5 mmol/L
    • HDL cholesterol less than 1.0 mmol/L for men and less than 1.3 mmol/L for women
    • LDL cholesterol greater than or equal to 3.5 mmol/L

    In order to get an accurate reading for the LDL cholesterol, people were required to fast for 8 hours or more beforehand. The results presented here refer only to those people who did fast (approximately 79% of adults who participated in the National Health Measures Survey (NHMS)).


TOTAL CHOLESTEROL

Total cholesterol is a measure of all the different types of fats in the blood. Abnormal or high total cholesterol is a major risk factor for coronary heart disease and stroke.1

In 2011–12, one in three Australians aged 18 years and over (32.8% or 5.6 million people) had abnormal or high total cholesterol levels according to their blood test results. Yet only 10.1% of this group self-reported having high cholesterol as a current long-term health condition, which suggests that the majority of people with high cholesterol results were either unaware that they had the condition or did not consider it to be a long-term or current problem. A further 19.1% of adults had a total cholesterol level that was close to the abnormal cut off (i.e. in the 5.0–5.4 mmol/L range).

The proportion of people with high total cholesterol levels increased with age, peaking at 55–64 years (47.8%), before decreasing in late adulthood. Overall there was no significant difference in rates of total cholesterol for men and women.

The NHMS also collected cholesterol information for children. Of those aged 12–17 years, 3.5% had high total cholesterol levels in 2011–12.

Graph Image for Persons aged 12 years and over - Proportion with high total cholesterol levels, 2011-12


Research shows that certain lifestyle risk factors, such as smoking and obesity, are associated with high cholesterol.2 In 2011–12, current smokers were more likely to have high cholesterol than people who never smoked (38.1% compared with 30.4%). Similarly, adults who were obese were more likely to have high cholesterol than those who were normal weight or underweight (37.0% compared with 25.8%).

People with high total cholesterol were also likely to have other indicators of cardiovascular disease. For example, 84.7% of those with high total cholesterol also had high LDL 'bad' cholesterol. They were also more likely than those with normal total cholesterol levels to have high triglycerides (22.9% compared with 9.5%). Similarly, people with high blood pressure had higher rates of total cholesterol that those with normal blood pressure (40.8% compared with 31.0%).

LDL CHOLESTEROL

LDL cholesterol is the measure of 'bad' cholesterol in the blood. Over time, LDL cholesterol can build up in the blood vessels and arteries, blocking the passage of blood flow.3

In 2011–12, one in three Australian adults (33.2%) had abnormal or high LDL cholesterol. High levels of LDL cholesterol were more common among men (35.0%) than women (31.6%).

Like total cholesterol, people aged 55–64 years had the highest rates of LDL cholesterol (45.7%). Rates then sharply declined from 65 years onwards. One in twenty children aged 12–17 years (5.2%) had high LDL cholesterol in 2011–12.

The associations between LDL cholesterol and health risk factors were very similar to that for total cholesterol, with higher rates of abnormal LDL cholesterol among smokers and those who were overweight or obese.

People with high LDL cholesterol were more likely to have high triglycerides than those with normal LDL levels (15.7% compared with 11.7%). However, there was no association between high LDL cholesterol and lower than normal HDL 'good' cholesterol.

HDL CHOLESTEROL

HDL cholesterol is the measure of 'good' cholesterol. HDL picks up excess cholesterol in the blood and takes it to the liver where it is broken down.3

In 2011–12, 23.1% of Australian adults had abnormal or low levels of HDL cholesterol. Abnormal HDL cholesterol was more prevalent for women (27.2%) than men (18.9%).

Unlike the other measures of cholesterol, levels of low HDL cholesterol remained fairly stable across all age groups at between 21.0% and 24.7%.

Graph Image for Persons aged 12 years and over - Proportion with low levels of 'good' cholesterol, 2011-12


People with low HDL cholesterol had a greater likelihood of also having signs of other chronic diseases. For example, 10.5% of those with low levels of HDL cholesterol also had diabetes, compared with 3.4% of those with normal levels. They were also more likely than those with normal HDL cholesterol to have high triglycerides and abnormal alanine aminotransferase (ALT) and gamma glutamyl transferase (GGT) levels, increasing their risk of heart and liver diseases.

For more information on cholesterol, see Tables 1, 2, 3, 4, 8, 9 and 15 on the Downloads page of this publication.

ENDNOTES

1 Australian Institute of Health and Welfare, 2013, High blood cholesterol, <http://www.aihw.gov.au/high-blood-cholesterol/>, Last accessed 18/06/2013. Back to top
2 National Heart Foundation of Australia, 2007, Policy paper: Tobacco and cardiovascular disease, <http://www.heartfoundation.org.au/SiteCollectionDocuments/TobaccoandCardiovascularDiseasePolicyPaper.pdf>, Last accessed 08/07/2013. Back to top
3 National Heart Foundation of Australia, 2013, Cholesterol, <http://www.heartfoundation.org.au/SiteCollectionDocuments/NAHU-Cholesterol.pdf>, Last accessed 08/07/2013. Back to top

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