1345.4 - SA Stats, May 2007  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 29/05/2007   
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This article presents data from the latest National Health Survey (NHS) which was conducted by the Australian Bureau of Statistics (ABS) from August 2004 to June 2005. Similar surveys were conducted in 1977-78, 1983, 1989-90, 1995 and 2001.

This article focuses on the height and body mass index of adults living in South Australia (SA) in 2004-05. This is the fourth in a series of articles looking at the health of South Australians. Previous articles were:


In the 2004-05 NHS, data were collected from people living in private dwellings in urban and rural areas of Australia; excluded were people in hospitals, nursing homes and other non-private dwellings. Of all the states and territories, SA had the oldest population in scope of the survey with just over 14% of the population aged 65 years and over, followed by Tasmania at just under 14%. By comparison, 12% of Australia's population in scope of the survey was aged 65 years and over. The older age structures in SA and Tasmania may impact on the health estimates for their populations.

Further information on the latest NHS can be obtained from the publication 'National Health Survey, Summary of Results, Australia, 2004-05' (cat. no. 4364.0), the Microsoft Excel tables in 'National Health Survey, Summary of Results: State Tables, 2004-05' (cat. no. 4362.0) and the publication Changes in health: A snapshot, 2004-05 (cat. no. 4834.0.55.001).


INFORMATION COLLECTED

Information was collected from people about their height and weight and this information was used to calculate their body mass index (BMI). People were asked whether they considered themselves to be overweight, of acceptable weight or underweight. It is important to note that 7% of males and 14% of females did not state their heights and/or weights and these people may not have the same distribution of body mass categories as people who reported their heights and weights.


BODY MASS INDEX

Based on self-reported height and weight, 34% of South Australian males were in the BMI category of normal range of weight for their height in 2004-05 compared with 41% of South Australian females. A statistically significantly higher proportion of males reported heights and weights indicating they were in the overweight category (40%) than females (25%). A further 19% of males and 17% of females were in the obese category.

The body mass index (BMI) is calculated from reported height and weight information, using the formula weight (in kilograms) divided by the square of the height (in metres). To produce a measure of the prevalence of overweight or obese adults, BMI values are grouped according to World Health Organization (WHO) and National Health and Medical Research Council (NHMRC) guidelines. An adult with a BMI of less than 18.5 is considered underweight, a BMI of 18.5 to less than 25.0 is considered to be in the normal range, a BMI of 25.0 to less than 30.0 is considered to be overweight and a BMI of 30.0 or greater is considered to be obese.

BODY MASS OF MALE AND FEMALE ADULTS REPORTING HEIGHT AND WEIGHT(a), SA, 2004-05

Graph: Body Mass of Male and Female adults reporting height and weight, SA, 2004-05
(a) Body mass not known for a further 7% of males and 14% of females.
Source: National Health Survey, Summary of Results: State Tables, 2004-05 (cat. no.4362.0)


Data from the 1995, 2001 and 2004-05 National Health Surveys show that the prevalence of overweight or obese adults has been increasing. In 2004-05, 50% of adults in SA reported heights and weights indicating they were overweight or obese compared with 45% in 2001 and 41% in 1995. Similarly at the national level, 49% of adults were overweight or obese in 2004-05, 46% in 2001 and 40% in 1995.

The following graph shows that the prevalence of overweight and obese adults has increased from 1995 to 2004-05 in all age groups in South Australia. The graph also shows that the age groups that had the highest proportions of overweight or obese adults in 2004-05 were 55-64 years (60%) and 45-54 years (59%). The largest increase is in the 35-44 year age group where the prevalence of overweight or obese adults was 43% in 1995 compared with 56% in 2004-05.

OVERWEIGHT OR OBESE ADULTS, BY AGE GROUP, SA, 1995 AND 2004-05
Graph: Overweight or Obese Adults, by Age Group, SA, 1995 and 2004-05
Source: National Health Survey, Summary of Results: State Tables, 2004-05 (Cat. no.4362.0)
and National Health Survey, 1995, data available on request


Based on data from the 1995 and 2004-05 survey years, the prevalence of overweight and obese adults increases with age, peaking at middle age, then tapering off and declining gradually for people aged 65 years and over. An alternative view is to consider the data as an age continuum. People aged 25-34 years in 1995 are aged 35-44 years a decade later (approximately 2004-05). In 1995, 36% of people aged 25-34 years were overweight or obese, increasing to 56% when they were aged 35-44 years a decade later. Similarly, in 1995, 43% of 35-44 year olds were overweight or obese. A decade later when this age group was 45-54 years old, 60% were overweight or obese. Similar changes occur for the group aged 45-54 years in 1995 who were aged 55-64 years in 2004-05. For the group 10 years older, the proportion overweight or obese stabilises over the ten year time period. In 1995, 55% of people aged 55-64 years were overweight or obese; 10 years later when this group was aged 65-74 years, 54% were overweight or obese. The following graph highlights these changes.

OVERWEIGHT OR OBESE ADULTS, BY BIRTH COHORT, SA, 1995 AND 2004-05
Graph: Overweight or Obese Adults, by Birth Cohort, SA, 1995 and 2004-05
Source: National Health Survey, Summary of Results: State Tables, 2004-05 (Cat. no.4362.0)
and National Health Survey, 1995, data available on request

Note that this analysis does not factor in other aspects such as older overweight or obese people may be more likely to move out of scope of the survey by dying or moving to non-private dwellings such as nursing homes earlier than people not overweight or obese. Further, the NHSs are not longitudinal studies where the same people are surveyed over time but are different samples representative of the Australian population in private dwellings.

PERCEPTION

In the NHS, people are asked whether they consider themselves to be overweight, of acceptable weight or underweight. In South Australia 58% of males and 42% of females reported heights and weights indicating they were overweight or obese but only 49% of these males and 68% of these females considered themselves to be overweight in 2004-05. Similarly at the national level, only 49% of males and 69% of females determined to be overweight or obese considered themselves to be overweight.

The following graph shows that overweight or obese males were less likely to perceive themselves as being overweight compared with overweight or obese females in the age groups of 18-44 years, 45-64 years and 65 years and over.

OVERWEIGHT OR OBESE ADULTS WHO PERCEIVE THEMSELVES TO BE OVERWEIGHT, SA, 2004-05
Graph: Overweight or Obese Adults, who Perceive themselves to be overweight, SA, 2004-05
Source: National Health Survey, 2004-05, data available on request


Based on reported heights and weights, 1% of males and 4% of females were underweight in both South Australia and Australia in 2004-05. Of these, only 44% of South Australian and 42% of Australian underweight adults perceive themselves to be underweight.


CHARACTERISTICS OF OVERWEIGHT AND OBESE ADULTS

South Australian adults with a degree, diploma or higher qualification and adults with no qualification were less likely to report heights and weights indicating they were overweight or obese (47% and 48% respectively) than adults with a trade certificate or other qualification (56%).

The following graph shows the prevalence of overweight and obese adults living in households ranked by the index of disadvantage (which is one of the Socio Economic Indexes for Areas (SEIFA)) at the Collection District level. Adults in households in the most disadvantaged group were more likely to be obese and less likely to be overweight than adults in households in the least disadvantaged group. Of those adults living in households in the first quintile (the most disadvantaged group), 28% were overweight and 22% were obese. By comparison, of those adults living in households in the fifth quintile (the least disadvantaged group), 32% were overweight and a statistically significantly lower percentage (11%) were obese.

OVERWEIGHT AND OBESE ADULTS BY SEIFA INDEX OF DISADVANTAGE, SA, 2004-05
Graph: Overweight or Obese Adults, by Seifa Index of disadvantage, SA, 2004-05
Source: National Health Survey, 2004-05, data available on request


The following graph shows that apart from exercise levels, overweight and obese adults reported similar levels of other risk factors (i.e. smoking, risky or high risk consumption of alcohol, and less than the daily intake of the recommended levels of fruit and vegetable serves). A statistically significantly higher proportion of obese adults reported sedentary or low levels of exercise (79%) compared with adults in the normal range of weights for their heights (68%).

OTHER RISK FACTORS, SA, 2004-05
Graph: Other Risk Factors, SA, 2004-05

Source: National Health Survey, 2004-05, data available on request


The following graph shows that higher proportions of obese adults considered themselves to be in poor, fair or good health compared with adults who were overweight or in the normal range of weight. There were also higher proportions of overweight adults who considered themselves to be in fair and good health compared with adults in the normal range of weight. Despite their obesity, 9% of obese adults considered themselves to be in excellent health and 27% in very good health.

SELF-ASSESSED HEALTH STATUS, SA, 2004-05
Graph: Self-assessed Health Status, SA, 2004-05
Source: National Health Survey, 2004-05, data available on request


Obese adults reported statistically significantly higher levels of high or very high psychological distress (16%) than adults who were overweight or in the normal range of weights for their heights (both 10%).

Overweight adults and obese adults reported similar levels of injury events requiring action in the previous 4 weeks (both 20%) compared with adults in the normal range of weights for their heights (21%).

About 90% of obese and overweight adults reported having a long term condition compared with 86% of adults in the normal range of weight for height. Another way of viewing these data is by comparing adults with a long term condition with adults without a condition: 51% of adults with a long term condition were overweight or obese compared with 41% of adults without a long term condition. The following graph shows some of the long term conditions with high proportions of overweight or obese adults.

PERCENTAGE OF ADULTS WITH SELECTED LONG TERM CONDITIONS WHO WERE OVERWEIGHT OR OBESE, SA, 2004-05
Graph: Percentage of Adults with Selected Long Term Conditions who were Overweight or Obese, SA, 2004-05
Source: National Health Survey, Summary of Results: State Tables, 2004-05 (cat. no.4362.0)


In 2004-05, 27% of obese adults consulted a general practitioner (GP) in a two-week period which is statistically significantly higher than the proportions of adults who were overweight or in the normal weight range (22% and 21% respectively). There were insignificant differences between percentages of obese, overweight and normal weight adults in consulting specialists, in consulting other health professionals or in taking days from work in a two-week period and the differences for having private health insurance were also insignificant.

SELECTED HEALTH RELATED ACTIONS, SA, 2004-05
Graph: Selected Health Related Actions, SA, 2004-05
Source: National Health Survey, 2004-05, data available on request


HEIGHT OF ADULTS

BMI is calculated using reported height. In 2004-05, younger South Australian adults reported heights that indicated they were on average taller than older South Australian adults. The following graph shows the proportion of males reporting a height of 180cm or more and the proportion of females reporting a height of 170cm or more by age group. It shows that 59% of 18-24 year old males reported they were 180cm or more compared with 27% of males aged 65 years and over. The graph also shows that 29% of 18-24 year old females reported they were 170cm or more compared with 12% of females aged 65 years and over.

Younger adults were less likely to report shorter heights. Only 3% of males aged 18-24 years reported they were less than 165cm compared with 9% of males aged 65 years and over. Fewer than half (46%) of females aged 18-24 years reported they were less than 165cm compared with 69% of females aged 65 years and over.

In the 1995 NHS, people reported their heights and then their heights were measured. Results from this survey showed that people tended to overestimate their height. For both males and females differences between reported and measured heights were greatest in the 65 years and over age group. For more details see How Australians Measure Up, 1995 (cat. no. 4359.0). For the 2005-05 NHS, people's heights were not measured and therefore over or under estimations cannot be determined for this survey.

HEIGHT OF ADULTS BY AGE GROUP, SA, 2004-05
Graph: Height of Adults by Age Group, SA, 2004-05
Source: National Health Survey, Summary of Results: State Tables, 2004-05 (cat. no.4362.0)


REFERENCES

National Health Survey: Summary of Results, 2004-05 (cat. no. 4364.0)
National Health Survey, Summary of Results: State Tables, 2004-05 (cat. no. 4362.0)
The companion data to National Health Survey: Summary of Results, 2001 (cat. no. 4364.0)