Correlates of STI testing among vocational school students in the Netherlands

Adolescents are at risk for acquiring sexually transmitted infections (STIs). In fact, worldwide, the prevalence of STIs is substantially greater in young adults than in many other populations [1]. Surveillance systems in various industrialized countries show that Chlamydia is the most commonly reported STI and that the highest prevalence of Chlamydia is observed among female adolescents [1, 2].

In 2008, national surveillance figures for the Netherlands showed a concentration of Chlamydia cases in heterosexual young people under 25 years of age with low to moderately educated adolescents living in urban centers being most at risk. Additionally, STI prevalence was found to be higher among adolescents of non-Dutch ethnicity such as Antillean and Surinamese adolescents [2, 3]. Because high risk immigrant adolescents do engage in sexual intercourse with their Dutch peers, this increases the likelihood of STI transmission between high and low prevalence groups. This kind of disassortative mixing, previously described in a Dutch study of high-risk migrant populations in the Netherlands, is most likely to occur among second generation and younger migrants [4]. Also, a nationwide cross-sectional study of sexual behavior among people aged 12 to 25 showed that participants with lower educational attainment exhibited more sexual risk behavior and less knowledge regarding STI and reproductive/contraceptive issues than their better educated counterparts [5].

Because effective prevention of STI relies on early case detection and treatment [6], the Netherlands offers free and anonymous testing facilities to populations at risk such as young people under the age of 25. Unfortunately, test rates among young heterosexual people remain low [5]. Interventions that promote STI testing among this risk group are thus imperative. Such interventions are particularly necessary among young adults attending vocational schools in urban areas. These students, generally aged 16 to 20, tend to be of non-Dutch ethnicity and are at risk for STI not only because of their lower level of education but also because they tend to have earlier sexual debuts and engage in more unsafe sex than Dutch-born adolescents, thus leading to more opportunities for STI exposure [5].

However, effective interventions that encourage STI testing among these students are severely limited, and no interventions have specifically targeted vocational students. Consequently, the Municipal Public Health Service (MPHS) in Rotterdam developed an intervention that targeted students attending vocational schools. This intervention was developed using the Intervention Mapping (IM) protocol, which proposes a stepwise approach to the theory and evidence-based development and implementation of interventions [7].

According to IM and to other health promotion planning models such as the Precede-Proceed Model [8], an important part in the first phase of intervention development (the needs assessment) is establishing important and changeable behavioral determinants of the target behavior. Globally, most studies on the determinants of testing behavior focus on populations at risk for HIV such as men who have sex with men (MSM) [9‐17] or on injection drug users (IDUs) [15, 18]. Although research on the determinants of HIV testing among MSM can be used to hypothesize the behavioral mechanisms of testing in heterosexual adolescents, the context of and social environment in which sexual risk taking among adolescents takes place is very different than it is among MSM. Also, the incidence as well as the perceived severity and consequences of infection differ substantially between HIV and other STIs affecting heterosexual adolescents in Western countries. Other studies have investigated which demographic variables and risk-taking behaviors are specifically related to STI testing among adolescents [19‐22] but none have explored the behavioral determinants of STI testing among young heterosexual adults with a low educational attainment in the Netherlands. Clearly, there is a paucity of research on the psychosocial determinants of STI testing among this group. Studies that employ a comprehensive theoretical framework are also scarce. Of the few studies that have employed a theoretical framework, some have used a stage model to assess readiness for STI testing [21‐23], some have employed the Health Belief Model [24‐26], and yet others have studied single psychological constructs such as shame and stigma associated with STI testing [27], social support related to STI and healthcare utilization [28] and attitudes [29].

In an effort to integrate the leading theories on behavioral prediction and behavioral change, Fishbein developed the Integrative Model of Behavioral Prediction [30, 31] (Figure 1). This model functioned as the theoretical framework for our study of the determinants of STI testing in vocational school students. The Integrative Model synthesizes aspects of the Theory of Reasoned Action (TRA), the Theory of Planned Behavior (TPB) [32], Social Cognitive Theory (SCT) [33] and the Health Belief Model (HBM) [34]. The model first suggests that behavior is caused by intention when skills to cope with environmental constraints are sufficient. The most proximal determinants of intention are attitude, perceived norms and self efficacy. The proximal determinants themselves are functions of sets of underlying beliefs. Background variables are considered to have an indirect influence on the proximal determinants through their impact on beliefs. Possible background variables for participating in STI testing among adolescents include risk perception (e.g. severity and worry) [26, 35], mood and emotions (e.g. shame), stigma attached to testing [27, 36], knowledge, interventions that promote testing, perceived accessibility and availability of testing services (e.g. the availability of oral and rapid test methods as well as free testing services) [26, 37], demographic variables and past testing behavior. In predicting intentions, past behaviour can also have a direct influence on intentions and has some variance in common that is not shared by attitude, perceived norms and perceptions of control [38]. The purpose of this study was to assess sexual risk behavior and STI testing, and to identify psychosocial and environmental factors predicting STI testing intention among sexually experienced adolescents attending vocational schools. The Integrative Model functioned as our theoretical framework.

This study has demonstrated a high prevalence of unsafe sex and low STI testing rates among sexually active students at vocational schools in the Netherlands. We examined if, and to what degree, the variables posited by the Fishbein's Integrative Model could predict students' intentions to participate in STI testing. We found that the Integrative Model variables successfully explained 39% of the variance and that intention to test was very low.

Similar to other studies [11, 36, 41, 45], we found that the proximal determinants intention, attitude and norms were significant predictors of STI testing. In contrast with other research that focused on HIV testing [11, 26, 45, 46], we found that self efficacy was not a significant predictor. This is, however, consistent with other research on HIV testing conducted in the Netherlands [41]. It is possible that this finding is attributable to the fact that participating in STI testing in the Netherlands is relatively easy to do. Test sites are readily available to adolescents.

In accordance with other studies, we found perceived susceptibility but not perceived severity to be a predictor of intention to participate in an STI test [25, 47]. Most of the students thought that STI were very severe (mean score of 1.78 at a scale of -2/+2; SD = 0.57). As a consequence, the data on severity were negatively skewed (scores clustering at the higher end of the scale). This situation statistically hinders the determination of a relationship between severity and intention. Perceived susceptibility was also found to be very low, given the self reported risk behavior. According to national guidelines, the sexual behavior of two thirds of the boys and half of the girls warrants an STI test [48] because students either had unprotected sexual intercourse with a casual partner in the past year (17% of the boys; 9% of the girls) or two or more sexual partners in their lifetime (66% of boys; 51% of girls) or both. Despite the significant risk, only 15% had previously been tested for an STI.

Also, our finding that easy access to testing facilities is a significant predictor of intention to test is consistent with studies on HIV testing in young adults [26, 37]. Providing testing for free, ensuring anonymity and confidentiality, offering testing services outside of office hours and providing options with regard to how one can receive one's test results all appear to contribute to intention to get an STI test.

In this study, girls reported having previously tested for an STI more often than boys. Their intention to test was also higher. That girls have more experience with STI testing may be due to the fact that girls tend to contact health care providers for reproductive health matters more than boys. They often visit their GP for a contraceptive prescription and thus have more opportunities to request an STI test than boys. Girls also scored higher than boys on all behavioral determinants of testing except self efficacy. However, despite of these differences in scores, there were no gender differences regarding which determinants were predictive for the intention to test. This is in contrast to other studies that suggest that behavioral determinants for testing are different for boys and girls. Such studies have indicated that fear of stigma might hinder girls but not boys in seeking STI-related care [23, 27].

The majority of the sample were of non-Dutch ethnicity (first and second generation migrants), which is typical for vocational students in Rotterdam and in other urban centers in the Netherlands. Our study did not demonstrate significant difference between students of non-Dutch ethnicity and Dutch students regarding testing behavior and the determinants of STI testing. This suggests that an intervention promoting testing that is geared to vocational students does not necessarily need to be tailored to differences in ethnicity. Such an intervention should, however, be tailored to risk behavior and the determinants of STI testing investigated in this study.

In short, we conclude that intention to participate in STI testing among this population of adolescents is primarily driven by attitude but also by norms. Because most students were unaware of the relevance of STI testing, we recommend that interventions first target testing awareness and then seek to establish a positive attitude toward testing via the specific beliefs that underlie attitudes toward testing [49]. For example, interventions may benefit from focusing on positive beliefs such as the advantages of a timely treatment, taking responsibility for one's health and communicating a positive message to one's partner. In order to increase the accessibility of pre-existing positive beliefs, priming strategies could be employed. Priming strategies attempt to increase the accessibility of specific beliefs in order to increase their influence on intentions, even in the absence of belief change [50]. An example of a priming strategy would be to incorporate certain beliefs in a movie and then discuss these with the target group afterwards. Additionally, the provision of information on the treatment and counseling procedure may function to remove worry about negative test results. Further, in order to establish positive social norms toward STI testing, the role of friends and parents should be addressed. A possible intervention could entail encouraging students to mobilize social support from friends. Another appropriate method is modeling which can change not only perceptions of social influence but also the social environment by changing the norms of peers [7]. Perceived susceptibility should be also addressed. Adequate perceptions of risk can be promoted through the personalization of risk. Lastly, easy access to testing facilities should be promoted and adolescents should be made aware of the availability of testing services.

The validity of this study is strengthened by its high response rate and the fact that the survey was systematically developed and based on both theory and evidence. A limitation to be considered is the size of the sample employed for the test-retest procedure (N = 39). Another limitation is the cross-sectional design of this study. Because of this, causality cannot be determined. However, in light of existing theory, the proposed causal direction is relatively probable. Furthermore, the correlation found between direct attitude toward testing and the sum score for beliefs was low (r = .23) thus indicating that we were unable to identify the most salient beliefs underlying students' attitude toward STI testing [49]. This is perhaps because we did not measure outcome evaluations. According to theory, beliefs should be multiplied by their outcome evaluations [38]. Outcome evaluations assess the item's evaluative implication for the individual and can be particularly useful for items that are ambiguous. For example, the outcome evaluation accompanying the item "getting an STI test is taking responsibility for my own health" would assign the degree to which the participant thinks that taking responsibility for one's own health is important. Another possibility is that we failed to measure all relevant beliefs or, because of a lack of compatibility, we failed to measure them correctly [49]. The measure of direct attitude toward testing used hypothetical situations while the measure of individual beliefs did not. However, scores on intention and its behavioral determinants were relatively low thus suggesting that students had not (yet) formed strong opinions regarding testing and that we measured non salient or less readily available beliefs. Despite these limitations, our findings reveal information on determinants of STI testing for an important target group. They thereby contributed to evidence that is essential for developing prevention interventions.

The present study provides important and relevant empirical input for the development of health promotion interventions that promote STI testing among adolescents attending vocational schools in the Netherlands. Theory and evidence on how health behavior can best be changed can contribute to the development of an effective intervention that promotes STI testing. According to the IM protocol [7], effective strategies and methods can be chosen for every important and changeable determinant when designing the intervention. The results of this study suggest that interventions promoting STI testing should aim to change attitudes, address social norms and elevate personal risk perception for STI. Additionally, the accessible nature of testing facilities should be promoted.