Title: Alcohol consumption trends in Australia: comparing surveys and sales-based measures

Transcription

1 Citation: Livingston, M., Callinan, S., Raninen, J., Pennay, A., & Dietze, P. M. (2017). Alcohol consumption trends in Australia: Comparing surveys and sales based measures. Drug and Alcohol Review. Online early. Title: Alcohol consumption trends in Australia: comparing surveys and sales-based measures Authors: Michael Livingston (PhD) 1,2 Sarah Callinan (PhD) 1 Jonas Raninen(PhD) 2, 3 Amy Pennay (PhD) 1 Paul Dietze (PhD) 4 1. Centre for Alcohol Policy Research, La Trobe University, Melbourne, Australia 2. Karolinska Institutet, Department of Clinical Neuroscience, Stockholm, Sweden 3. The Swedish Council for Information on Alcohol and Other Drugs (CAN), Stockholm, Sweden 4. The Burnet Institute, Melbourne, Australia Corresponding author: Michael Livingston La Trobe University 215 Franklin Street, Melbourne, 3000 m.livingston@latrobe.edu.au Abstract word count: 209 Word count: 2275 Table count: 2 (plus 2 in an appendix) Running head: Australian alcohol consumption trends Key words: Alcohol, trends, surveys 1

2 Abstract Introduction and aims: Survey data remain a crucial means for monitoring alcohol consumption, but there has been limited work done to ensure surveys adequately capture changes in per-capita consumption in Australia. In this study we explore how trends in consumption from two major Australian surveys compare with an official measure of per-capita consumption between 2001 and 2014 and examine age-specific trends in drinking. Design and methods: Data were from five waves of the cross-sectional National Health Survey (total n=113,279) and twelve waves of the longitudinal Household Income and Labour Dynamics in Australia study (average n=12,347). Overall and age-specific estimates of annual alcohol consumption were derived and compared with official per-capita consumption and previous analyses of the National Drug Strategy Household Survey. Results: In terms of overall consumption, both surveys broadly reflected trends in per-capita consumption, especially the decline that has been observed since 2007/08. Age specific trends were broadly similar, with the recent decline in consumption clearly concentrated among teenagers and young adults. Discussion and conclusions: The main Australian monitoring surveys remain useful monitoring tools for alcohol consumption in Australia. There is consistent evidence that the recent declines in Australian per-capita consumption have been driven by sharp falls in drinking among young people, a trend that requires further study. 2

3 Alcohol consumption trends in Australia: comparing surveys and sales-based measures Introduction Per-capita alcohol consumption has varied substantially in Australia recently, increasing from litres of pure alcohol per person in 2001/02 to a peak of litres in 2006/07 before declining to 9.71 litres in 2013/14 (1). Understanding this variation is critical to understanding alcohol s impact on health and social problems linked to alcohol. Per-capita alcohol consumption relies on aggregated data based on excise tax collection, imports and exports meaning that fine-grained analyses of these trends needs to rely on other data sources, predominantly surveys. Social surveys from several high-income countries, including Australia (1), show marked declines in youth drinking over the last two decades (2, 3). These declines appear to have been the key influence on recent trends in per capita consumption in Australia, with sharp declines in drinking among younger cohorts pushing overall consumption down (4). While surveys typically underestimate per-capita consumption (3, 4) they may still capture temporal trends. We recently used the Australian National Drug Strategy Household Survey (NDSHS) to examine alcohol consumption between 2001 and The survey data captured some of the increase in per-capita consumption reported in sales data that occurred between 2001 and 2007 and accurately estimated its subsequent decline (5). The relative accuracy of the overall trend data in the NDSHS allowed us to explore whose drinking contributed to the changes in per-capita consumption. There were markedly different trends across age groups, with the increase largely driven by increasing consumption among year olds, while the post-2007 declines came about due to sharp falls in consumption among year olds. In this study we attempt to replicate these previous Australian findings by exploring trends in overall and age-specific per-capita alcohol consumption from two additional Australian survey series (The National Health Survey and the Household Income and Labour Dynamics in Australia study) that use different approaches to data collection and different survey items to the NDSHS (and to each other). Replication of our previous findings would suggest that population surveys are a viable tool for monitoring alcohol consumption in Australia and would confirm the sharply divergent trends in consumption by age reported in the NDSHS. Methods Data 3

4 Per-capita consumption data (for the population aged 15+) were sourced from the Australian Bureau of Statistics (6). As with our previous work (5), we have averaged the ABS financial year estimates to approximate calendar year volumes. It is worth noting that while we treat the ABS per-capita estimates as our benchmark, there are numerous limitations to these kinds of estimates including problems with conversion factors (7) and unrecorded consumption ((8), although this is not a major issue in Australia). While the ABS estimates are not a perfect reflection of Australian alcohol consumption, they provide the best available benchmark to assess survey estimates against. We examine trends in two survey data sources the Household Income and Labour Dynamics in Australia survey (HILDA) and the ABS National Health Survey (NHS) and compare these results with previous analyses of the National Drug Strategy Household Survey (NDSHS) (5). HILDA Annual waves of the longitudinal Household Income and Labour Dynamics in Australia (HILDA) survey have been administered since The original national probability sample consisted of 7,682 Australian households. All members of selected households complete the survey and when household members move they are retained, followed to their new home and any additional occupants are recruited as new participants. As this method can result in under-representation of immigrant families a top-up sample of 2,153 households was added to the sample in Surveys involve face to face and drop and collect questionnaires, with self-complete drop-and-collect reserved for questions that might be more prone to response bias (including consistent items on alcohol consumption from 2002 for those aged 15 and over). Waves 2 to 13 ( ) are used for the current study. Survey weights for age, sex and location are available and further details of the survey can be found in the appendix (Table A1) and the HILDA technical reports (9). NHS The National Health Survey (NHS) is a general health survey conducted by the Australian Bureau of Statistics with waves available from 2001, , , and In each wave households were sampled using a random, multi-stage sampling approach with a sub-sample of individuals living in each household selected to provide detailed health information. Data were collected by trained interviewers in face-to-face surveys, with non-english speaking interviewers available when necessary. Alcohol consumption data were collected for all respondents aged 15 and over, except in 2001 when all under-18s were excluded. Details of each survey wave are provided in the Appendix (Table A2) and in the NHS survey reports (10-14). Consumption measures 4

5 HILDA respondents were asked how often they currently consume alcohol. No time frame is given for respondents, with the item intending to capture current patterns of drinking. There are seven response categories, ranging from never to every day. They were then asked how many standard drinks (10g alcohol likely smaller than a typical drink consumed, especially for wine (15, 16)) they consumed on a usual drinking occasion. Estimated annual volume was calculated by multiplying the respondents drinking frequency by their usual quantity (e.g. the annual consumption of someone who drank 5 standard drinks, once a month was estimated as 60 drinks). Standard drinks were converted to millilitres of pure alcohol (1 standard drink = 12.7ml of pure alcohol). NHS respondents were asked a unique set of items to measure alcohol consumption in the week before the survey. Recency effects are likely to improve the accuracy of the responses (17) but many infrequent drinkers are treated as non-drinkers by virtue of having no drinking occasions in the previous week, while occasional drinkers who drank in the past week will have their consumption over-estimated (18). Respondents provide detailed data of beverage type (including brand) and volume (in natural containers e.g. 3 pints of XXXX Gold beer, etc.) consumed for up to three drinking occasions. These data are then converted into litres of pure alcohol and estimates of average weekly consumption are derived from the amounts consumed and the number of drinking days. As brand-specific data were collected, the exact alcohol content of most reported beverages could be used in this conversion. Where generic responses were given (e.g. white wine ) conversion factors developed by the ABS and consistent with their approach to estimating per-capita consumption were used across 17 different beverage categories (19, 20). There have been some changes to the wine conversion factors used in the apparent consumption time series (see (21)), but these have been applied retrospectively and changes are relatively small post-2001, meaning comparability of total consumption should not be affected. We use this estimate of weekly consumption multiplied by 52 to estimate the average annual volume of pure alcohol consumed by people who drank in the week before responding to the NHS. Respondents who did not drink in the past week were treated as abstainers (i.e. they consumed 0ml of pure alcohol). This measure excludes drinkers whose most recent drink was more than a week ago, while infrequent drinkers who happened to consume alcohol in the week before the survey are treated as weekly drinkers. This is not ideal, but is likely to capture much of the drinking done by Australians (e.g. 94% of all alcohol consumed by respondents to the National Drug Strategy Household Survey in 2013 was consumed by drinkers who drank weekly or more often (unpublished analyses)). Analysis 5

6 Estimates of the annual volume of pure alcohol consumed based on each survey source were calculated (along with 95% confidence intervals) and compared with per-capita consumption estimates from the ABS. We focus in particular on whether the two surveys capture the increasing consumption trend between 2001 and 2007 and the decreasing consumption trend subsequent to Sub-analyses examine the same trends across age groups, to replicate the earlier estimates derived from the NDSHS. Total volumes of alcohol consumed by each age group and the proportion of total consumption each contributed are presented to provide a further perspective on the changing distribution of consumption. Results Table 1 shows that each survey substantially underestimates ABS consumption data, with the NHS and NDSHS typically capturing a little over half of the consumption estimated from excise data, while HILDA captured around one-third. Table 1 Litres of pure alcohol consumed per capita, survey data and ABS apparent per-capita consumption Year NHS (18+) 1 HILDA (15+) 2 NDSHS (15+) 3 ABS ( ) ( ) (4.01, 4.29) (3.87, 4.14) ( ) 3.96 (3.82, 4.1) 5.80 ( ) (3.99, 4.33) (3.92, 4.21) ( ) 4.08 (3.93, 4.22) 5.79 ( ) (3.97, 4.28) (3.98, 4.31) (3.79, 4.07) 5.63 ( ) ( ) 3.8 (3.68, 3.92) (3.61, 3.85) (3.48, 3.72) 5.18 ( ) ( ) - Change 2001/ % -1.8% +0.9% 6.3% Change / % -11.7% -10.5% -8.9% 1. National Health Survey 2. Household Income and Labour Dynamics of Australia Study 3. National Drug Strategy Household Survey (data from (5)) 4. Australian Bureau of Statistics apparent consumption data (6) Trends in consumption Estimates from the NHS broadly follow the ABS trends, increasing between 2001 and 2007 and declining subsequently. The scale of both the increase and, particularly, the decline were more 6

7 marked in the survey data than in the ABS data. HILDA consumption estimates were stable between 2002 and 2009 and then declined sharply through All three surveys recorded marked declines in consumption post 2007, broadly consistent with sales trends (although the decline in the NHS data is steeper than the decline in sales). Age patterns Table 2 shows that all three surveys found that the decline in consumption after 2007 was concentrated among younger respondents, especially for those between 15 and 29. For year olds each survey records declines of 45% or more, while declines for young adults were between one-fifth and one-third. Table 2 Changes in mean alcohol consumption by age group survey data NHS 1 HILDA 2 NDSHS 3 Age group Change Change Change Change Change Change n.a. -56% -0% -71% -25% -45% % -41% -5% -31% -1% -26% % -32% 9% -29% 5% -20% % -13% 0% -20% 6% 8% % -18% 3% -6% 6% 0% % -14% -5% 1% 1% -6% % -13% -9% -4% 3% 6% 70+ 6% 4% -9% 7% -6% -4% 1. National Health Survey 2. Household Income and Labour Dynamics of Australia Study 3. National Drug Strategy Household Survey (data from (5)) There is some variation in trends across surveys. For example, the NHS and HILDA both find substantial declines in consumption for year olds after 2007, which are not reflected in the NDSHS data. Trends among older respondents vary between surveys but are generally small in magnitude. Across all three surveys the declines in per-capita alcohol consumption after 2007 appear to be driven by large declines in the drinking of adolescents and young adults. To illustrate the absolute impact of these trends, age-specific estimates of the absolute volume of alcohol consumed by each age group in the NHS and HILDA are provided in Table 3. The declines for the younger age groups are substantial in both volume and in terms of their contribution to the overall level of consumption. For example, between 2007 and 2014, the proportion of all alcohol consumed by year olds in the NHS declined from 25.3% to 19.3%, an absolute decline of 7.4 7

8 megalitres. In contrast, total alcohol consumption for respondents aged 30 and over has declined by just 2 megalitres. Similarly, in the HILDA data this proportion was 22.0% in 2007 and 17.1% in Table 3 Total alcohol consumption (megalitres of pure alcohol) by age group and proportion of total alcohol consumption each age group consumed, , National Health Survey and HILDA Study. NHS Age group 1 HILDA n.a. 0.8 (0.9%) 0.3 (0.4%) 1.4 (2.5%) 1.5 (2.5%) 0.4 (0.7%) (13.3%) 13.6 (14.3%) 8.7 (10.2%) 6.8 (12.2%) 6.8 (11.8%) 5.3 (9.3%) (10.4%) 9.6 (10.1%) 7.5 (8.8%) 4.3 (7.7%) 4.5 (7.7%) 4.0 (7.1%) (21.5%) 17.6 (18.5%) 16.4 (19.1%) 10.3 (18.4%) 10.1 (17.6%) 8.3 (14.7%) (21.3%) 19.3 (20.3%) 16.3 (19.0%) 11.7 (21.0%) 11.9 (20.6%) 12.0 (21.3%) (17.7%) 17.1 (18.0%) 16.5 (19.3%) 9.6 (17.1%) 10.3 (17.9%) 11.5 (20.4%) (9.3%) 11.2 (11.8%) 12.4 (14.5%) 6.5 (11.7%) 7.4 (12.8%) 8.5 (15.2%) (6.6%) 5.9 (6.2%) 7.5 (8.7%) 5.2 (9.4%) 5.2 (9.1%) 6.3 (11.2%) Total 1. National Health Survey 2. Household Income and Labour Dynamics of Australia Study Discussion Australian surveys appear to do a reasonable job of measuring overall consumption trends, with trends in both the NHS and HILDA surveys broadly in line with trends in per-capita consumption at the population level. No particular survey was the most accurate at measuring consumption HILDA and the NDSHS under-estimated the increase in consumption up to 2007, while the NHS overestimated the subsequent decline. When age-specific trends are examined there is substantial variation between surveys, although a consistent picture emerges that declines in overall alcohol consumption in Australia have largely been driven by declines in drinking by young people (aged < 30). There are some variations across other age groups that suggest caution is still required when interpreting trends from any individual survey series (e.g. in the NHS year old consumption increased by 24% between 2001 and 2007 but by just 3% in the NDSHS). The consistency of the findings around youth and young adult drinking provide more empirical evidence that younger generations in Australia are drinking at much lower levels than their equivalents years ago. The reasons for these declines are unclear, although similar trends have been identified in many countries since the early 2000s, including North America and most of Europe (with declines in Eastern Europe and Australia evident from the mid-2000s) (2, 22, 23). A range of 8

9 plausible reasons for these declines have been suggested (24, 25). In Australia, there is evidence that parental practices have changed (26) and that broad attitudes to alcohol are becoming more negative (27), but more research is necessary to understand these shifts. Both the HILDA and NHS surveys have important limitations. The measure used by the NHS to collect alcohol consumption has been critiqued for its inability to measure the consumption of infrequent drinkers (28), but the consistency of this limitation means that the trends analysed here are still meaningful. The slight differences in the conversion factors used to estimate alcohol volumes between the NHS and ABS per-capita consumption data will introduce a small amount of bias in the comparison of these data sources over time, but the differences are so small that they are unlikely to influence the overall findings presented here. The HILDA study is a panel survey and not strictly intended to monitor population-wide trends. However, with the cross-sectional survey weights provided it remains broadly representative of the Australian population and provides a means of triangulating the trends identified in the other major Australian surveys. The use of different measures of alcohol consumption between surveys is both a limitation and a strength. Each measure has its own biases (e.g. the simple QF measure in the HILDA survey tends to smooth out variable drinking patterns, while the NHS measure is overly influenced by a short time window. These may have different effects by age, but the broad consistency found across now three different approaches to measurement provides encouragement that the particular survey biases are not driving the changes observed. Finally, a further potential limitation is our inability to assess agespecific response rates in these large-scale surveys. Both HILDA and the NHS have seen increases in non-response over the study period (see Appendix) and, if this increase was concentrated among young people, then the age-specific trends examined here could be an artefact. The broad consistency of the overall consumption trends across the surveys and the ABS per-capita consumption data mitigates this possibility somewhat, but these findings should still be treated with caution. Acknowledgements This research was supported under Australian Research Council's Discovery Projects funding scheme (project numbers DP and DP ). ML is supported by an NHMRC Career Development Fellowship (GNT ). The authors gratefully acknowledge the Victorian Operational Infrastructure Support Program received by the Burnet Institute. The Centre for Alcohol Policy Research is funded by the Foundation for Alcohol Research and Education, an independent, 9

10 charitable organization working to prevent the harmful use of alcohol in Australia Data from The National Health Survey were provided by the Australian Bureau of Statistics. This paper uses unit record data from the Household, Income and Labour Dynamics in Australia (HILDA) Survey. The HILDA Project was initiated and is funded by the Australian Government Department of Families, Housing, Community Services and Indigenous Affairs (FaHCSIA) and is managed by the Melbourne Institute of Applied Economic and Social Research (Melbourne Institute). The findings and views reported in this paper, however, are those of the author and should not be attributed to either FaHCSIA or the Melbourne Institute. 10

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