4363.0.55.001 - National Health Survey: Users' Guide - Electronic Publication, 2007-08
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 14/09/2009
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This document was added or updated on 17/09/2009. CONTENTS
Other health risks may be indicated through information obtained in the survey about other health and related characteristics, such as the presence of particular long term conditions. The collection of information about health risk factors and behaviours in conjunction with other health and population characteristics enables all elements to be analysed together. However, while data from the survey may suggest apparent associations between particular risk factors and certain medical conditions, the data should not be interpreted as indicating causal relationships. Some caution should be used in drawing together data for the different risk factors covered, as the reference periods used differ, e.g. smoking at time of interview, alcohol consumption in the last week, exercise in the last week and last two weeks. However, when used with care, data from the NHS can describe populations which may be at special risk due to the presence of combinations of risk factor behaviours and characteristics. Most of the specific risk factors covered have been addressed in previous ABS surveys, either at national or State/ACT levels. Major changes in the coverage of risk factors between the 2007-08 NHS and the 2004-05 NHS are summarised in the table below.
Where appropriate to the survey vehicle and consistent with the data requirements of users, similar methodologies were employed in the 2007-08 NHS to those used in previous surveys to enhance comparability and enable use of the data for analysing changes over time. Comments regarding comparability between the 2007-08 and 2004-05 NHS are contained in the individual topic descriptions which follow. A more general discussion of time series issues relating to the 1989-90, 1995 and 2001 surveys is contained in Occasional Paper: Health Risk Factors - a Guide to Time Series Comparability from the National Health Survey, Australia (ABS cat. no. 4826.0.55.001). SMOKING Definition This topic refers to the smoking of tobacco, including manufactured (packet) cigarettes, roll-your-own cigarettes, cigars and pipes, but excluding chewing tobacco and smoking of non-tobacco products. The topic focused on ‘regular smoking’, where 'regular' was defined as one or more cigarettes (or pipes or cigars) per day as reported by the respondent. The topic primarily describes smoking status at the time of interview; i.e. current smokers (daily, weekly and other), ex-smokers, and those who had never smoked 100 cigarettes, nor pipes, cigars or other tobacco products at least 20 times, in their lifetime. Methodology Respondents were asked whether they currently smoke. Respondents who answered yes were asked whether they smoked daily. Those who did not smoke daily were asked whether they smoked at least once a week. Along with respondents who reported that they did not currently smoke, they were then asked whether they had:
If a respondent did not currently smoke, or had never smoked at least 100 cigarettes, nor smoked pipes, cigars or other tobacco products at least 20 times in their life, they were classified as persons who had never smoked, and sequenced to the questions about other people in the household. Current daily and ex-daily smokers were asked the age they had started smoking. Ex-daily smokers were asked whether they had stopped smoking regularly in the last 12 months, and the age they were when they stopped smoking regularly. Current smokers were asked whether their smoking had increased, decreased or stayed the same in the last 12 months, and whether they usually smoked inside the house. Respondents in households other than single person households were asked whether anyone else in the household smoked regularly, and if so, the number of people and whether they usually smoked inside the house. Population Information was collected for persons aged 15 years and over. Please note that this differs from previous NHSs where these questions were asked of persons 18 years and over. Data items Output categories for the data items used in the 2007-08 survey are available from the list of output data items available for download from the National Health Survey: Users' Guide, 2007-08, (cat. no. 4363.0.55.001) and the National Health Survey: Data Reference Package, 2007-08 (cat no. 4363.0.55.002). Please note that:
Interpretation Points to be considered in interpreting data from this survey include the following:
Comparability with 2004-05 Data for most smoking items are directly comparable between the 2004-05 and 2007-08 surveys. New items collected in 2007-08 are:
In both surveys, other smokers in the household could include children. As noted above, smoking information for the 2007-08 survey was collected for persons aged 15 years and over, whereas in the 2004-05 NHS, it was only collected for persons aged 18 years and over. ALCOHOL CONSUMPTION Definition This topic refers to consumption of alcoholic drinks, and focuses on two aspects of consumption:
Intake of alcohol refers to the quantity of alcohol contained in any drinks consumed, not the quantity of the drinks themselves. Methodology Respondents aged 15 years and over were asked how long ago they last had an alcoholic drink. Those who reported they had a drink within the previous week were asked the days in that week on which they had consumed alcohol (excluding the day on which the interview was conducted), and for each of the most recent three days in the last week on which they drank, the types and quantities (number and size) of drinks they had consumed. They were also asked whether their consumption in that week was more, about the same, or less than their usual consumption. Information was collected separately in respect of the following categories of alcoholic drinks:
Respondents who reported having beer or wine were asked supplementary questions to identify the type (e.g. light beer, white wine), as shown above. If interviewers were unsure in which category a reported drink belonged, details were recorded in ‘other alcoholic drinks’ for checking/reclassifying as appropriate during office processing. Respondents were asked to report the number of drinks of each type they had consumed, the size of the drinks, and where possible the brand name(s) of the drink(s) consumed on each of the most recent three days in the last week on which they had consumed alcohol. The collection of accurate data on quantity of alcohol consumed is difficult, particularly where recall is concerned, given the nature and possible circumstances of consumption. Interviewers were provided with extensive documentation and training to assist with recording of amounts consumed. Where possible, information was collected in terms of standard containers or measures; i.e. 10 oz glass, stubbie, nip, etc. Where the size of the drink did not readily fit into the list provided to interviewers, they were asked to record as much information as necessary to clearly indicate quantity. Reported quantities of drinks consumed were converted to millilitres of alcohol present in those drinks, and then summed to the drink type, day, and week level as required. The methodology to convert drinks to mls of alcohol consumed is as follows:
This conversion was performed electronically, supported by clerical coding for cases which could not be coded automatically. Where precise brand x type of drink information was not recorded, default alcohol content values based on drink type were applied. These values are shown below:
It is recognised that particular types or brands of beverage within each of these categories may contain more or less alcohol than indicated by the conversion factor, e.g. full-strength beers are usually in the range 4% to 6% alcohol by volume. The factors are considered to be sufficiently representative of each category as a whole for the purposes of indicating relative health risk as appropriate to the aims of this survey. However, it should be noted that these categories, defined by the conversion factors used, may not reflect legal definitions. In addition to information about alcohol consumed in the previous week, respondents who reported they had drunk alcohol in the previous 12 months were asked about the number of times (days) in that period on which they had consumed:
Respondents who reported that they had drunk alcohol in the last 12 months were also asked about their level of consumption compared to 12 months ago. Population Information was collected for persons aged 15 years and over. Please note that this differs from previous NHSs where these questions were only asked of persons 18 years and over. Data items Output categories for the data items used in the 2007-08 survey are available from the data item list available for download from the National Health Survey: Users' Guide, 2007-08, (cat. no. 4363.0.55.001) and the National Health Survey: Data Reference Package, 2007-08 (cat no. 4363.0.55.002). Interpretation Points to be considered in interpreting data on alcohol consumption from this survey include the following:
Comparability with 2004-05 The methodology used in the 2007-08 survey for the collection of data about the quantity of alcohol consumed was essentially the same as that used in the 2004-05 survey. Results for the two surveys are therefore considered directly comparable. There were, however, some changes to the questionnaire and supporting coding systems used in 2007-08 which involved updating and expanding the index lists supporting the system used to derive alcohol intake. These changes were aimed at improving the accuracy with which alcohol intake was derived from reported consumption. As the main sources of error in this topic are reporting errors, these changes should only have a marginal impact on the overall quality of alcohol consumption data. In drawing comparisons, consideration should also be given to the social factors and general changes in health awareness which have occurred in the period between surveys and which may have influenced the levels of reporting. New items collected in 2007-08 are:
As noted above, alcohol information for the 2007-08 survey was collected for persons aged 15 years and over, while in the 2004-05 NHS it was only collected for persons aged 18 years and over. EXERCISE Definition This topic covers three components of physical activity:
Methodology Current physical activity guidelines for Australian adults include at least 30 minutes of moderate-intensity physical activity on most, preferably all, days. To gauge levels of activity, respondents were asked a series of questions about the exercise they undertook in the last week and last two weeks, expressed in the three categories of walking, moderate exercise and vigorous exercise. For the purposes of the survey, moderate exercise was defined as exercise undertaken for fitness, recreation or sport that caused a moderate increase in the heart rate or breathing of the respondent. Vigorous exercise was defined as exercise undertaken for fitness, recreation or sport that caused a large increase in the respondent’s heart rate or breathing. The application of these definitions reflected the respondent’s perception of moderate or vigorous exercise or walking, and the purpose of that activity. Responses may have varied according to the type of activity performed, the intensity with which it was performed, the level of fitness of the participant, and their general health and other characteristics (e.g. age). For example, some respondents may consider a game of golf to be moderate exercise while others may consider it walking. Information was not recorded in the survey about the type of activities undertaken. Respondents were asked whether they did any:
For each of these categories of exercise, respondents were asked:
The two-week time period was maintained in 2007-08 to allow data to be compared to previous surveys. The move to the one-week reference period allows some comparability over time, as well as aiding the calculation of whether the respondent met physical activity guidelines. Respondents who answered these questions were also asked about their level of activity compared to 12 months ago. From the information recorded about the frequency, duration and intensity of exercise undertaken for fitness, recreation or sport, an exercise level was derived for each respondent. The aim was to produce a descriptor of relative overall exercise level, and to indicate the quality of the activities undertaken in terms of maintaining heart, lung and muscle fitness. Whether a person has met physical activity guidelines is calculated using the following formula:
where intensity, or metabolic equivalent of task (MET), is a measure of the energy expenditure required to carry out the exercise, expressed as a multiple of the resting metabolic rate (RMR). As the survey did not collect details of the types of activities undertaken, an intensity value was estimated for each of the three categories of exercise identified in the survey, as follows:
A score was derived for each of the three categories of exercise and then summed to provide a total for the respondent for that period. Respondents were grouped into exercise levels according to their score. For the two week period, score ranges were grouped and labelled as follows:
After the specific exercise questions, all respondents were asked whether they had walked in the previous week for periods of 10 minutes or more, for the purpose of going from place to place (i.e. for transport, not for fitness, recreation or sport). Those who had done so were asked the number of times they had walked for transport in the last week and the total time walked. Respondents who were employed were asked whether their usual activity at work during a typical work day was mostly sitting, mostly standing, mostly walking, or heavy labour. Full-time employees were asked to report the amount of time (hours and minutes) they spent sitting at work during a usual work day, and the amount of time (hours and minutes) they spent sitting watching television and using the computer before and after work. All other respondents were asked to report the time (hours and minutes) they spent sitting while watching television and using the computer on a usual week day, and all respondents were then asked to report the amount of time (hours and minutes) they spent sitting in other leisure time on a usual work/week day. Data is not available separately for time spent in leisure due to the potential overlap of responses (e.g. persons may have reported the same activity for 'time spent sitting at the computer' and 'time spent sitting in other leisure time'). There may be other activities which were not included by respondents, so this data should be used with caution. Data from the questions on walking for transport, level of activity at work and time spent sitting do not contribute to the calculations of exercise level. Population Information was collected for all persons aged 15 years and over. Data items Output categories for the data items used in the 2007-08 survey are available from the data item list available for download from the National Health Survey: Users' Guide, 2007-08, (cat. no. 4363.0.55.001) and the National Health Survey: Data Reference Package, 2007-08 (cat no. 4363.0.55.002). Interpretation Points to be considered when interpreting data relating to exercise for fitness, recreation or sport include the following:
Points to be considered when interpreting data relating to walking for transport include the following:
Comparability with 2004-05 The majority of the data on exercise for fitness, recreation and sport were collected in the 2007-08 NHS with the same methodology and questions used in the 2004-05 survey, and therefore most results are considered directly comparable. The following changes, however, should be noted:
Over recent years there has been an increasing focus by governments and media on health and lifestyle issues around obesity and physical activity. While such attention is likely to influence the levels of activity in the community, it may also have an impact on reporting behaviour; for example, creating a tendency to report what is perceived to be a desirable level of activity rather than actual activity. This should be considered in interpreting changes between results from 2007-08 and 2004-05. New items for the 2007-08 survey include:
BODY MASS Definition This topic refers to:
Methodology Self-reported height and weight Respondents were first asked whether they considered themselves to be underweight, an acceptable weight or overweight. Women who identified that they were pregnant at the time of the interview were sequenced out of the module at this point. Remaining respondents were asked whether their weight had increased, decreased or stayed the same since 12 months ago. They were then asked to report their weight and height without shoes. Answers provided in imperial measurements were recorded by interviewers and converted into metric measurements. If respondents rounded their weight or height (e.g. 'about 6 feet') interviewers prompted for a more exact measure where possible. Physical measurements Physical measurements were taken towards the end of the survey. All physical measurements were voluntary, and women who had identified they were pregnant were not measured. Interviewers used digital scales to measure weight, a stadiometer to measure height, and a metal tape measure (which avoided the risk of the tape stretching) to measure waist and hip circumference. Thorough interviewer training identified the points at which hips and waists were to be measured (as recommended by Australian government health agencies), as well as how to take the measurements with the least amount of interviewer and respondent discomfort (either holding the end of the tape at the appropriate point and asking the respondent to turn around until the tape met, or asking the respondent to hold the end of the tape and walking around them until the tape met). Interviewers encouraged respondents to remove their shoes and any heavy clothing, e.g. jumpers, before they took measurements, however, this was voluntary, and may not have occured in some cases. Interviewers were not required to record if they thought clothing may have impacted significantly on measurements. Weight was recorded in kilos to one decimal point, and height, waist and hip measurements were recorded in centimetres to two decimal points. If a respondent's waist or hip measurement was more than two metres, it was recorded as 200.00. Body mass index scores Body mass index (BMI) scores were derived using Quetelet’s metric body mass index which is calculated as weight (kg) divided by height (m)2. BMI scores are commonly grouped for output. Although certain ethnic groups, including Asian and Indigenous people, have been shown to have an increased prevalence of disease at much lower BMIs than Europeans (Wood, 2007), the NHS is not able to differentiate for ethnicity, therefore BMI cut-off points are those established for people of European origin. The output classification for adults used for this survey is shown below:
While the formula to calculate BMI scores is the same for adults and children, the classification of children's BMI is different to that of persons aged 18 years and over, and takes into account individual age and sex. BMI cut-off ranges for children 2 to 17 years of age are included in Appendix 5: Classification of BMI for children. The NHS uses the half-year cut-off points to calculate children's BMI scores for persons aged 5 to 17. For more information on this classification please refer to the list of output data items available for download from the National Health Survey: Users' Guide, 2007-08, (cat. no. 4363.0.55.001) and the National Health Survey: Data Reference Package, 2007-08 (cat no. 4363.0.55.002). Waist circumference Waist circumference reflects mainly subcutaneous abdominal fat storage, and has been shown to positively correlate to disease risk (NHMRC, updated 12 March 2004). The scale used for determing risky waist circumference in the 2007-08 NHS is that recommended by the World Health Organisation, (See Obesity: preventing and managing the global epidemic. Report of a WHO Consultation, 2000). As with BMI, the cut-off points in this scale are best used for people of European origin, however, as ethnicity cannot be determined in the NHS, the same cut-off points are used for all respondents.
Waist to hip ratio The waist to hip ratio (WHR) is a simple measure of central obesity. The score from the WHR predicts the risk of developing several conditions associated with excess abdominal fat. Excess abdominal fat distribution is indicated by a WHR greater than 0.8 for women and 0.9 for men. Population Self-reported information was collected from persons aged 15 years and over. Physical measures were obtained for persons aged 5 years and over. Data items Output categories for the data items used in the 2007-08 survey are available from the data item list available for download from the National Health Survey: Users' Guide, 2007-08, (cat. no. 4363.0.55.001) and the National Health Survey: Data Reference Package, 2007-08 (cat no. 4363.0.55.002). Waist and hip measurements, and self-reported and measured height, weight and body mass index scores are stored on the data file and can be grouped in output to suit individual user needs. Interpretation When interpreting data for this topic, users should bear in mind that:
Comparability with 2004-05 Data collected on self-reported height and weight in the 2007-08 NHS used the same methodology and questions as the 2004-05 survey and are therefore directly comparable with 2004-05 results. There are, however, a number of significant differences for Body Mass items in 2007-08:
New items for 2007-08 include:
DIETARY BEHAVIOURS Definition This topic covers selected dietary indicators relating to type of milk consumed and usual daily intake of fruit and vegetables. National dietary guidelines recommend a minimum number of serves of fruit and vegetables according to age. Methodology Respondents were asked to report the main type of milk they usually consumed, categorised as follows:
The fat content of milk usually consumed (i.e, whole milk, reduced-fat, skim) was then reported for persons who drank milk. Interviewers were able to access fat content for each milk type on their screens to assist in classification. Respondents were then asked to report the number of serves of vegetables and of fruit they usually eat each day. For the purposes of this survey:
Prompt cards were used to assist respondents in understanding the concept of a serve, showing pictorial representations as used by the State of Western Australia, 2007. One prompt card showed three pictorial examples of single serves of different vegetables and another card showed three pictorial examples of single serves of fruit. If respondents had difficulty in reporting, interviewers were encouraged to prompt in terms of asking respondents about their usual consumption of vegetables and fruit at breakfast, lunch and dinner, and for snacks. Respondents were also asked whether their vegetable and fruit consumption had increased, decreased or stayed the same since this time last year. Population Information was collected for persons aged 5 years and over. Please note that this differs from the 2004-05 NHS where these questions were asked of persons 12 years and over. Data items Output categories for the data items used in the 2007-08 survey are available from the data item list available for download from the National Health Survey: Users' Guide, 2007-08, (cat. no. 4363.0.55.001) and the National Health Survey: Data Reference Package, 2007-08 (cat no. 4363.0.55.002). Interpretation Points to be considered in interpreting data for this topic include the following:
Comparability with 2004-05 Many dietary indicator questions used in the 2007-08 NHS were similar to those used in the 2004-05 NHS and the data are considered broadly comparable. However, as outlined above, information for the 2007-08 survey was collected for persons aged 5 years and over, whereas in the 2004-05 NHS, information was collected for persons aged 12 years and over. There were significant differences between the prompt cards used in the two surveys to assist respondents in determining the size of a serve of fruit or vegetables. This may have had some impact on the comparability of the data. Items collected in 2004-05 that were not collected in 2007-08:
New items for 2007-08 include:
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