Alcohol consumption among university students in Ireland and the United Kingdom from 2002 to 2014: a systematic review

Background Alcohol is a leading cause of global suffering. Europe reports the uppermost volume of alcohol consumption in the world, with Ireland and the United Kingdom reporting the highest levels of binge drinking and drunkenness. Levels of consumption are elevated among university students. Thus, this literature review aims to summarise the current research on alcohol consumption among university students in the Republic of Ireland and the United Kingdom. Methods MEDLINE, CINAHL, EMBASE and PsychInfo were systematically searched for literature from January 2002 until December 2014. Each database was searched using the following search pillars: alcohol, university student, Ireland or the United Kingdom and prevalence studies. Results Two thousand one hundred twenty eight articles were retrieved from electronic database searching. These were title searched for relevance. 113 full texts were retrieved and assessed for eligibility. Of these, 29 articles were deemed to meet inclusion criteria for the review. Almost two thirds of students reported a hazardous alcohol consumption score on the AUDIT scale. Over 20 % reported alcohol problems over their lifetime using CAGE while over 20 % exceed sensible limits each week. Noteworthy is the narrowing of the gender gap throughout the past decade. Conclusion This is the first review to investigate consumption patterns of university students in Ireland and the United Kingdom. A range of sampling strategies and screening tools are employed in alcohol research which preclude comparability. The current review provides an overview of consumption patterns to guide policy development.


Background
Alcohol consumption is of considerable public health concern and a leading cause of global suffering [1]. Of particular concern are the health issues and social effects associated with its use [2][3][4][5]. Patterns of alcohol consumption range between continents and countries. Recent figures from the World Health Organisation (WHO) demonstrate that the European Region (E.U.) is the heaviest drinking region in the world [6]. Consumption levels peak in both the Nordic countries and the British Isles including the United Kingdom and Ireland [7,8].
Elevated levels of alcohol consumption among young adults aged 18-29, of which university students represent a unique population, is of particular concern [9]. Research suggests that students today drink more, with increasing emphasis on binge drinking and drunkenness than among earlier generations [10][11][12][13]. Authors have previously hypothesised this as the 'psychoactive revolution' and by the 1990's, a decade defined by a 'new culture of intoxification' had manifested which plateaued in 2001 [14]. Internationally, an extensive volume of research has been conducted to investigate the prevalence of hazardous alcohol consumption among students [15]. These studies range in methodological approaches and quality and have resulted in varying response rates. Also, unlike many other health behaviours which apply a standard approach to measurement, a variety of alcohol screening tools have been developed to categorise alcohol consumption levels. This impacts on the ability to compare and contrast when reviewing research in the area. A number of reviews of nations and continents have been undertaken.
Policy-makers and health system managers routinely legislate for complex issues such as alcohol consumption [16]. Systematic reviews are an integral feature of informing effective public health policy. Public policy makers "are less likely to be misled by results of a systematic review than a single investigation and can thus be more confident about the consequences a decision might produce" [16]. National strategies have highlighted the importance of tackling university student alcohol consumption when reducing population levels [17]. The Republic of Ireland and the United Kingdom both report high levels of harmful drinking among university students. Moreover, they provide state-funded universities which are independently run. These differ from Nordic countries which provide free undergraduate degrees to students. Thus, this literature review aims to summarise all available information on the prevalence of alcohol consumption among university students in the Republic of Ireland and the United Kingdom from 2002 to 2014.

Eligibility criteria
Following a scoping exercise, inclusion criteria for this review were as follows: 1) Cross-sectional studies which reported a prevalence of alcohol consumption, 2) Studies conducted within a university/college student population, 3) Studies conducted at universities or colleges in the United Kingdom or the Republic of Ireland and 4) studies published between January 1 st 2002 and December 31 st 2014. Any research article which did not correspond to each of these criteria was excluded.
Information sources and search strategy MEDLINE, EMBASE, CINAHL and PsychInfo were systematically searched for literature from January 2002 until December 2014. For each database, searching was conducted using a combination of the following search terms: alcohol*, alcohol drinking, alcoholism, alcohol behaviour, university student*, College student*, Ireland, United Kingdom, Britain, prevalence, cross-sectional and questionnaire*. Search terms were combined using the Boolean logic of AND or OR operators. Completed searches were title searched for relevant articles by one reviewer (MPD). Irrelevant articles were excluded at this stage. All articles which referred to the research question were downloaded. Table and abstracts were analysed to investigate suitability (MPD and FS) and relevant articles were fully reviewed (MPD and FS). A flow diagram of this is displayed in Fig. 1. References for all included articles were managed in Endnote, a reference package, to keep track of paper selection.

Screening tools
Data extraction highlighted a number of screening tools available to university students.
The Alcohol Use Disorders Identification Test (AUDIT) was developed by the World Health Organisation to identify excessive drinkers. This screening tool identifies Fig. 1 Flowchart of studies included in the review hazardous patterns of alcohol consumption. The AUDIT-C takes the first three questions of the AUDIT questionnaire. These questions focus on the frequency of consumption, the number of units consumed and the number of binge drinking occasions. The guidelines are provided on safe alcohol consumption. Separate guidelines are provided for men and women with lower low-risk thresholds for women than those for men reflecting their increased vulnerability to alcohol related harm [18].
The CAGE questionnaire is favoured in the primary care setting due to the fact that it is short and easy to remember. It asks four questions; Have you ever felt you should cut down on your drinking? Have people annoyed you by criticising your drinking? Have you ever had a drink first thing in the morning to steady your nerves or to get rid of a hangover? The CAGE can identify alcohol problems over the lifetime. Two positive responses are considered a positive test and indicate further assessment is warranted.
The remaining studies, eligible for inclusion in this review, employed the screening tool FAST or the number of units consumed as a measure of risky drinking behaviour. Authors used binge drinking which is defined as six or more units in one drinking session. Other studies noted the number of weekly units exceeding nationally recommended weekly limits.

Data items and quality assessment
Data extraction forms were utilised in the current research. Data was extracted on sociodemographic, methodological and alcohol information by one author (MPD). This was reviewed by a co-author (FS) and any disagreements discussed with a third co-author (IJP). Data was extracted under the following headings:  Table 1 displays the results of the quality assessment Quality assessment was undertaken using the quality assessment tool outlined by Loney et al [19] to appraise prevalence studies. The tool investigates three main areas: 1) Are the study methods valid, 2) What is the interpretation of the results? and 3) What is the applicability of the results? Each criteria was given a point and each study marked out of a total of eight.

Data synthesis
Relevant data extracted from eligible studies are presented in Table 2. Due to the number of different screening tools and variety of sampling strategies, a narrative review was conducted. This yielded a summary of the prevalence of alcohol consumption according to screening tool and further subdivided by gender when possible. Figure 1 displays the results of the search strategy. Of the included studies, seven employed the AUDIT scale [20][21][22][23][24][25][26]. This is based on the frequency of consumption, the number of units consumed, the number of binge drinking occasions along with a range of second-hand effects of excessive alcohol use. A further five studies employed the CAGE questionnaire [27][28][29][30][31]. However, different cut-off scores were used across these studies. Seventeen studies questioned students on the units of alcohol they consumed. Of these seven describe binge drinking patterns [32][33][34][35][36][37][38], 6 describe exceeding sensible limits of weekly consumption [39][40][41][42][43][44], 3 describe hazardous drinking [45][46][47] and 1 risky drinking [48]. A proportion of studies reported consumption patterns by gender (n = 15).

Study characteristics
In addition, a number of different sampling strategies were reported. These ranged in cluster size from students registered to a number of university campuses across the UK, to students in one university, to students in one faculty or department. Summaries of each study are displayed in Table 2.

Summary of results AUDIT
Among studies which employed the AUDIT scale, the proportion of students reporting hazardous alcohol consumption ranged from 62.8 % in 2003 to 84 % in 2014. In 2010, Beenstock reported results from a crosssectional survey of university students at a university in Northern England. Using a university-wide sampling frame, 82 % reported an AUDIT score of eight or more, a rise in previous years. In 2011, Heather reported on hazardous alcohol consumption across seven universities in the United Kingdom. 60.6 % of the sample reported hazardous alcohol consumption. In 2012 Gunby reported results from a university in North West of England which found 71.2 % of students reported hazardous alcohol consumption. When sports students were questioned, O'Brien reported 84 % were hazardous alcohol consumers after delivering questionnaires to all sports venues in a 2 mile radius of ten universities across England. hazardous alcohol consumers. However, O'Brien did not note any significant differences in male and female drinking patterns in their 2014 article [20][21][22][23][24][25][26].

CAGE
Among the five studies which employed the CAGE screening tool, the proportion of students reporting alcohol problems ranged from 22 to 76 %. In 2011, El Ansari reported findings that 23.1 % of students were problem drinkers from a study of seven participating universities. Similarly, Sebena reported 22.1 % of first year students registered to one English university reported problem drinking while El Ansari, 2013 noted 22.4 % of students across seven universities in the UK were problem drinkers.       Provide an explicit statement of questions being addressed with reference to participants, interventions, comparisons, outcomes, and study design (PICOS).

Protocol and registration 5
Indicate if a review protocol exists, if and where it can be accessed (e.g., Web address), and, if available, provide registration information including registration number.
-Eligibility criteria 6 Specify study characteristics (e.g., PICOS, length of follow-up) and report characteristics (e.g., years considered, language, publication status) used as criteria for eligibility, giving rationale.

Information sources 7
Describe all information sources (e.g., databases with dates of coverage, contact with study authors to identify additional studies) in the search and date last searched.

Search 8
Present full electronic search strategy for at least one database, including any limits used, such that it could be repeated.

Study selection 9
State the process for selecting studies (i.e., screening, eligibility, included in systematic review, and, if applicable, included in the meta-analysis).
✓ Data collection process 10 Describe method of data extraction from reports (e.g., piloted forms, independently, in duplicate) and any processes for obtaining and confirming data from investigators.

Data items 11
List and define all variables for which data were sought (e.g., PICOS, funding sources) and any assumptions and simplifications made.

12
Describe methods used for assessing risk of bias of individual studies (including specification of whether this was done at the study or outcome level), and how this information is to be used in any data synthesis.

Summary measures 13
State the principal summary measures (e.g., risk ratio, difference in means). ✓

Synthesis of results 14
Describe the methods of handling data and combining results of studies, if done, including measures of consistency (e.g., I 2 ) for each meta-analysis.

Risk of bias across studies 15
Specify any assessment of risk of bias that may affect the cumulative evidence (e.g., publication bias, selective reporting within studies).
-Additional analyses 16 Describe methods of additional analyses (e.g., sensitivity or subgroup analyses, meta-regression), if done, indicating which were pre-specified. -

Study selection 17
Give numbers of studies screened, assessed for eligibility, and included in the review, with reasons for exclusions at each stage, ideally with a flow diagram.

Study characteristics 18
For each study, present characteristics for which data were extracted (e.g., study size, PICOS, followup period) and provide the citations.

Risk of bias within studies 19
Present data on risk of bias of each study and, if available, any outcome level assessment (see item 12). ✓

Results of individual studies 20
For all outcomes considered (benefits or harms), present, for each study: (a) simple summary data for each intervention group (b) effect estimates and confidence intervals, ideally with a forest plot. One of the largest studies was conducted across seven universities in the United Kingdom. It contradicts this, noting 29.3 % of men report problem drinking compared to 20.4 % of women [27][28][29][30][31].

Units
The remaining 17 studies gave information on the number of units consumed by students. These studies describe students as heavy drinkers, hazardous drinkers, binge drinkers or drinkers who exceed sensible limits. For those papers which reported binge drinking, Gill

Discussion
The breadth of literature published on university student consumption highlights alcohol as the leading cause of concern among this sub-section of society [50,51]. Although recent research has noted decreasing levels of alcohol consumption among young adults, hazardous alcohol consumption continues among university students in Ireland [15] and the United Kingdom [23]. This review highlights the high levels of alcohol consumption among university students and the narrowing proportions of risky drinking in male and female students. A generation of intoxication occurred in the 1990's following a static period for alcohol consumption during the 70's and 80's. Since its peak in 2001, drunkenness and binge drinking have become commonplace among young adults [14]. However, it is difficult to conclude whether excessive consumption is due to a cultural shift in consumption patterns or as a direct result of alcohol marketing.
The current review highlights a range of issues that present themselves when synthesising results from alcohol research studies. Firstly, the representative nature of included studies ranged significantly. A variety of sampling procedures and populations in each research article was reported. Included articles ranged from medical students, a cross-section of students from a single university or a cross-section of a number of universities across the UK or Ireland. The most prominent issue with cross-sectional research is selection bias. This occurs as non-participation in surveys is rarely random [52]. Levin noted that "the sample frame used to select a sample and the response rate determine how well results can be generalised to the population as a whole" [53]. Large scale cross-sectional studies are optimum as they sample the whole population. When the sampling frame is narrow, the concern of the researcher is that the sample will differ from the general population and results cannot be generalised, thereby reducing the external validity. When interpreting these results, the reader needs to consider systematic error (difference between the sample and the population) and particularly coverage error for studies which focused solely on medical or dental professions [54].
Secondly, in contrast to many other risk taking behaviours such as smoking or illicit drug use, alcohol can be considered both a protective (cardiovascular disease) and a risk factor (cancer) at low doses [55]. Much research has been conducted into devising screening tools for categorising harmful and non-harmful consumption [56][57][58]. A plethora of screening tools are now available and validated in both general and specific populations. The difficulty of having a broad variety of screening tools is that comparison is compromised when countries or institutions within countries employ different screening tools. The current review notes the use of AUDIT, CAGE and units. In addition, other screening tools such as FAST, RAPT and T-ACE have been developed and validated for use. Table 3 PRISMA checklist for systematic reviews (Continued) Limitations 25 Discuss limitations at study and outcome level (e.g., risk of bias), and at review-level (e.g., incomplete retrieval of identified research, reporting bias).

Conclusions 26
Provide a general interpretation of the results in the context of other evidence, and implications for future research.

Funding 27
Describe sources of funding for the systematic review and other support (e.g., supply of data); role of funders for the systematic review.

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The current review supports our recent research indicating that patterns of alcohol consumption among male and female students are converging [15]. The past two decades has seen an increase in female alcohol consumption, the inauguration and continuation of 'ladette culture' and a focused effort on marketing alcohol directly at young female women [59]. The implications of this consumption is more serious given women's innate biological susceptibility to the harms associated with alcohol consumption [2].
Tackling alcohol related harm among university students and the general population does not have a single solution but requires a suite of initiatives. Tax increases, minimum unit pricing, restricted access to retail alcohol and bans on alcohol advertising have been proven to effectively reduce the levels of hazardous drinking and alcohol related harm. Ireland and Scotland recently proposed the implementation of a minimum unit price for alcohol. Furthermore, the Irish government have committed to a suite of measures directed toward advertising, marketing and sponsorship being reviewed in three years, exposing their commitment to tackling this public health issue into the future.

Strengths and weaknesses
The current review gives a broad overview of alcohol consumption patterns among university students since 2002. The PRISMA checklist was utilised to guide the review process (Table 3). The search strategy was conducted using a number of different search engines which yielded relevant literature from a wide range of medical and psycho-social disciplines. This provides synthesised information for policy-makers to draw upon [16].
This review also has a number of limitations. The interpretation of the findings of this review was restricted due to varying methods and tools used in calculating hazardous alcohol consumption. Recently, the 'Cochrane Handbook for Systematic Reviews of Interventions' notes that if studies are clinically diverse then a metaanalysis may be meaningless. A particularly important type of diversity is in the comparisons being made by the primary studies. The current review combines studies which have employed different sampling strategies, different methods of data collection and opposing screening tools. Furthermore, it was advised that conducting meta-analyses of studies that are at risk of bias may be seriously misleading. Thus a meta-analysis has not been conducted in the current review due to the level of heterogeneity observed. In addition, one unit of alcohol is measured differently in Ireland and the United Kingdom, the impact of which was not controlled for in this review. However, this review does highlight the prominent consumption patterns among university students across these similar university environments.

Conclusion
Hazardous alcohol consumption continues to be the most prevalent public health issue encountered by university students. Despite increased efforts, levels of consumption among students have continued to increase throughout the past number of decades. These levels of consumption remain a primary concern to those attempting to improve student health and well-being. The current research provides public policy makers with an up-to-date summary of research to guide prevention efforts. As nations attempt to reduce alcohol related harm, a spotlight on the excessive consumption patterns among university students showcases the need for interventions to achieve national goals.