Although health inequalities among adolescents have been reported to be smaller than those observed for younger or older age groups [1, 2], it is known that health inequalities among adolescents are widening [3]. Health risk behaviours that are adopted during adolescence are known to track strongly into adulthood [4–6]. These behaviours, which include smoking, heavy alcohol consumption and drug use, have all been shown to contribute to excess morbidity and mortality during adulthood [7]. Furthermore, it has been identified that tobacco, alcohol and drug use [8, 9] and sexual risk taking behaviour [9, 10] are two of the major causes of death and illness among adolescents and young adults. It is thus important to understand trends in health inequalities and the underlying social determinants of these in order to develop interventions and policies to reduce the effects of these upon population health [11, 12].

In order to understand factors exacerbating ill-health and perpetuating inequalities, calls have been made for more research focused upon the experience of vulnerable and socially excluded populations [13]. One population that is currently under-represented within the UK literature is adolescents attending Alternative Education Settings (AES). This is because most large scale population surveys of adolescent health in the UK are conducted in mainstream schools, thus excluding AES pupils [14]. AES are defined by the UK Department of Health as education arranged by local authorities for “permanently excluded pupils” and “other children who, because of exclusion, illness or other reasons”, for instance behavioural problems, learning disabilities and developmental delays, “would not receive suitable education”. AES are also attended by pupils “subject to a fixed-period exclusion of more than five days” [15]. The most common reasons for referral to AES in the UK are: physical assault of teaching staff and pupils; persistently disruptive behaviour in the classroom; risk taking behaviours such as youth offending, substance use and high risk sexual behaviour; and teenage pregnancy [16–18]. Around 6500–7000 pupils in Scotland attend these settings each year, with published statistics aggregated to include both primary and secondary schools pupils [19].

Young people in AES, particularly those who are attending due to behavioural problems, disengagement from education and repeat exclusions from mainstream education settings (MES), may be particularly susceptible to adopting health risk behaviours. This is because health risk behaviours such as sexual risk-taking and substance use, which often start during adolescence, are associated with deprivation and social exclusion [20–24]. For example, in a representative sample of 15–16 year olds in Scotland, higher sexual risk was associated with deprivation, living in a lone-parent household, low levels of parental monitoring, living in a care/foster home and having limited educational/career aspirations [25, 26]. These factors are also associated with school exclusion [27], which in turn can increase the likelihood of antisocial and risky behaviours [28]. Where this includes being exposed to and using substances, evidence from adolescent cohort studies suggests that this is associated with poorer sexual health outcomes for adolescents, including earlier sex, higher numbers of sexual partners, earlier pregnancies and risk of contracting sexually transmitted infections (STIs) [29–32].

Although little is known about the health risk behaviours of AES in the UK, evidence utilising cross-sectional, self-reported data from young people in the USA, the Netherlands and New Zealand reveal high rates of health risk behaviours among AES pupils, including cigarette smoking [33–36], alcohol consumption [33–35], drug use [33–37] and sexual risk behaviour (e.g. early sexual initiation, poor contraceptive use and increased levels of teenage pregnancy) [35, 38–42]. The most rigorously conducted of these, the 1998 National Alternative High School Youth Risk Behaviour Survey (ALT-YRBS), used probability sampling techniques to create a nationally representative sample of pupils attending AES (mean age 16.8 years) in the United States [33]. The authors reported that: 64.1% of AES pupils smoked cigarettes; 64.5% consumed alcohol; 49.8% engaged in episodic heavy drinking (i.e. they had consumed 5+ drinks on two or more days in the preceding month); 84.5% had tried marijuana; and 53% reported being current users of marijuana. In all cases, males were significantly more likely than females to use substances [33]. Looking specifically at sexual behaviour, the ALT-YRBS study reported that: 87.8% of AES pupils were sexually active; 22% had been under the age of 13 at sexual initiation; and 50.4% had had four or more sexual partners. Around half (45.6%) of male AES and two thirds (63.9%) of female AES reported that they had not used condoms at last sexual intercourse [33]. Similar prevalence rates were reported in a New Zealand study of AES pupils [43].

Few studies have compared the health risk behaviours of AES and MES pupils [34, 36, 44]. Comparing the prevalence of health risk behaviours found within the 1998 ALT-YRSB with an age- and ethnicity- matched sample from the 1997 Youth Risk Behaviour Survey (YRBS), Grunbaum et al. [34] concluded that AES pupils were significantly more likely than MES pupils to smoke cigarettes (70.1% vs. 36.3%), consume alcohol (64.9% vs. 50.8%), use marijuana (53.9% vs. 26.2%), and be sexually active (85.5% vs. 48.3%). Sexually active AES pupils were also significantly more likely to report that they had had 4+ sexual partners (48.0% vs. 16%) and that they had not used a condom at last sexual intercourse (52.5% vs. 43.1%). The same pattern of significantly elevated risk has been reported in comparative studies of AES and MES pupils conducted in New Zealand [36] and Hong Kong [44].

The high levels of risk taking behaviours observed among AES pupils has resulted in their being described by society as ‘marginalised’, ‘disenfranchised’, ‘troubled’, ‘problem’, ‘bad’ and ‘failing’ youth [45–50]. These descriptions not only stigmatise young people in AES, but act as a barrier to understanding the wider socio-environmental and cultural factors that may perpetuate health inequalities by placing the onus for poor health outcomes upon individual choices and behaviours [50]. However, both quantitative and qualitative evidence suggests that the socioeconomic and familial characteristics of pupils within AES may increase their propensity to display increased levels of health risk-taking behaviours. Young people attending AES disproportionately come from low-income and lone-parent households. They are also more likely to have been exposed to social and familial adversity (e.g. parental mental ill-health, parental substance use and domestic violence), been maltreated as a child and be known to social work and criminal justice systems [16, 51–54]. These same factors have been identified by the UK Government as key drivers of social exclusion, and can increase the health risks of young people over time in the UK and beyond [55–58]. Thus, it is likely that in addition to familial factors, school exclusion contributes to health inequalities for AES pupils by acting as a barrier to young people being exposed to prosocial peers and adults, resulting in them receiving less monitoring and supervision, spending more time with other disadvantaged pupils, and being at increased risk of exposure to risky behaviours, including sexual risk-taking behaviours [59].

Although the literature suggests that disadvantage across multiple social contexts may underpin the increased levels of health risk behaviour observed among AES, to date, studies exploring the antecedents of substance use and sexual risk taking behaviours among AES have focussed mainly upon exploring associations between interpersonal factors and health risk behaviours. Looking first at family factors, it has been reported that AES pupils who perceive greater family connectedness or caring have lower levels of marijuana and cocaine use [60], are less likely to be sexually active [40] and are more likely to use condoms during intercourse [40]. Beyond familial factors, several studies have identified the associations between peers, educational aspirations and substance use. For instance, alcohol and drug use among peers has been found to be associated with substance use among AES, and also contributed significantly to the experience of negative consequences associated with substance use in adulthood [61]. Social isolation (e.g. having fewer friends) was associated with an increase in the number of monthly substances used among AES [62], while having lower educational aspirations was associated with increased cocaine use [60].

While these findings provide valuable insight into the factors associated with elevated levels of risk-taking among AES they are limited by the fact that they focus solely upon explaining how single risk factors, for instance lack of parent-child connectedness, explain the increased levels of risk observed among samples of AES pupils. Within the public health literature it has been identified that the most effective behaviour change interventions are based upon understanding behaviours and the settings in which they occur [63]. The social ecological model (SEM) is a theoretical framework that can be used to demonstrate that human health is shaped through the complex interaction of individual- (e.g. sex, economic status, knowledge, attitudes and behaviour), interpersonal- (e.g. social networks, social and familial support), organisational- (e.g. polices within organisations that affect how services are delivered to individuals), community- (e.g. relationships between organisations and institutions) and policy- (e.g. local and national laws) factors [64]. In order to reduce risk taking among vulnerable and socially excluded groups such as AES pupils, the framework of the SEM can be used to help understand how factors operating at multiple levels contribute to health risk behaviours [65].

Drawing upon the SEM, this study aims to build upon existing research by using multivariable regression models to explore, for the first time, how individual (socioeconomic status, age and gender) and interpersonal (familial, educational and peer) factors contribute to substance use behaviours and sexual risk taking among AES and MES pupils. We also aim to explore whether differences in the underlying socio-economic, familial, educational and peer factors of AES and MES pupils can help to explain why AES have significantly higher rates of health risk behaviours when compared with their contemporaries in MES [50]. Other studies have not compared AES and MES across school settings in this way. In order to meet these aims, three research questions (RQ) will be addressed:

1. Do socio-economic, family, education and peer background factors differ between AES and MES pupils in the UK?
2. Do rates of PSU and sexual risk behaviours differ between AES and MES pupils in the UK?
3. Can potential differences in rates of PSU and sexual risk-taking between AES and MES pupils in the UK be explained by individual (sex, age and socioeconomic circumstances) and interpersonal (family, education, and peer) factors?

In answering these questions, we provide the first UK based estimates of substance use and sexual risk taking behaviour among AES pupils.