Most adolescents who participate in school-based screenings for sexually transmitted infections do not perceive themselves at high risk of sexually transmitted infection

INTRODUCTION

Participation in screenings for sexually transmitted infections (STIs) in schools is voluntary. ^1–3 This raises the issue of students who voluntarily participate in school-based screenings for STIs who may self-select for participation based on certain common characteristics, biasing thereby the outcomes of these screening programmes. ⁴ Statements of study limitations have been made in a number of reports that voluntary participants in school-based screenings for chlamydia and gonorrhoea may be individuals who self-select for participation because they perceive themselves at high risk of STI. ^5–7 If among participants in school-based STI screenings a markedly higher proportion perceive themselves at high risk of STI compared with the general adolescent population, the resulting prevalence and other outcomes derived from these screening programmes might over or underestimate their corresponding measures in the source adolescent population. But whether participants in school-based screenings for STIs are individuals who perceive themselves at high risk of STI has not been ascertained. We surveyed ninth through 12th grades students participating in the New Orleans school-based screening for chlamydia and gonorrhoea to determine their perceived personal risk of STI.

METHODS

The New Orleans school-based screening for chlamydia and gonorrhoea, conducted annually since the school year 1995–1996, has been described in detail previously. ⁷ During the 2003–2004 and 2004–2005 screenings, 3336 students who were providing urine specimens for chlamydia and gonorrhoea testing were asked in a self-administered questionnaire to complete the statement ‘your chances of getting infected with a sexually transmitted disease are’. This statement was adapted from one submitted to 9th and 10th grade students by Ellen et al. ⁸ Options for completing the statement were none, not very high, medium, pretty high and very high. Students who estimated that their chances of getting infected with an STI were pretty high or very high were categorized as perceiving themselves at high risk of STI, and those who estimated that their chances were none, not very high or medium were categorized as not perceiving themselves at high risk of STI. Proportions in risk perception with 95% confidence intervals (CI) were calculated. The prevalence of chlamydia and gonorrhoea (number of students receiving positive test results [BD ProbeTec ET System, Sparks, MD, USA]) among students screened was also determined, and comparisons of prevalence by categorization of risk perception were made. χ² and t tests were used in statistical comparisons, with significance set at P < 0.05.

RESULTS

There were 423 students (12.7%) who tested positive for chlamydia or gonorrhoea, including 397 (11.9%) who tested positive for chlamydia and 80 (2.4%) who tested positive for gonorrhoea. Of 1183 students who were categorized as perceiving themselves at high risk of STI, 162 (13.7%) tested positive for chlamydia or gonorrhoea compared with 261 of 2153 (12.1%) among students who were categorized as not perceiving themselves at high risk of STI (P = 0.19; Table 2).

DISCUSSION

It has consistently been shown that most adolescents do not perceive themselves at high risk of STI. ^9–13 In the USA, among 408 sexually active women aged 14–19 enrolled in a clinics-based prospective study of adolescents’ HIV/STI risk behaviours in Connecticut, 78% thought they were only slightly or not at all at risk of STI. ^9,10 In a representative sample of sexually active young Americans surveyed in the National Longitudinal Study of Adolescent Health, 85% of men and women between the ages of 18 and 20 did not perceive themselves at risk of STI. ¹¹ In New Zealand, 77% of 538 male and female high school students aged 16–18 in Christchurch felt that it was unlikely that they would get a sexually transmitted infection. ¹² In Nepal, 77% of 348 sexually active male and female migrant factory workers aged 14–19 felt that they were not at all at risk of contracting any STI or HIV/AIDS. ¹³

In our study of 3336 male and female high school students who were participating in a school-based screening for chlamydia and gonorrhoea, 64% estimated that their chances of getting infected with an STI were not pretty high or very high. Chances of getting an STI were estimated similarly between gender, race and grade, and infection rates for chlamydia and gonorrhoea were similar between students who estimated that their chances of getting an STI were pretty high or very high and those who estimated that their chances of getting an STI were none, not very high or medium. The finding that 64% of students tested for chlamydia and gonorrhoea estimated, at the time of testing, that their chances of getting an STI were not pretty high or very high indicates that most participants in the New Orleans school-based screening for chlamydia and gonorrhoea do not, like most adolescents, perceive themselves at high risk of STI.

The 36% of students in our study who estimated that their chances of getting infected with an STI were pretty high or very high on our 5-point risk scale is greater than the proportions of adolescents within the same age-range in other studies who perceived their risk of STI to amount to high. ^9–13 Several explanations are possible. First, different studies used different measurements to assess the perception of respondents’ risk of STI, which may explain some of the differences. Second, we found a high prevalence of chlamydia and/or gonorrhoea (13%) in our student population. The exposure of adolescents to STIs may be different in New Orleans compared with other locations, especially where rates of STIs are lower. At least one study reported an association between individuals’ perception of their risk of HIV/AIDS and their perceived local prevalence of HIV, ¹⁴ suggesting that perception of personal risk of STI may be associated with individuals’ perception of their local prevalence of STIs. A third explanation may be that more adolescents who perceive themselves at high risk of STI seize the opportunity offered by a school-based screening for STIs. However, our study implies that participation in the New Orleans school-based screening for chlamydia and gonorrhoea of individuals who self-selected because they perceived themselves at high risk of STI is less than 36%, because it is unlikely that perception alone would have prompted all those who estimated that their chances of getting an STI were pretty high or very high to initiate a clinic visit to seek STI testing elsewhere, had they not been offered a population screening for STIs at school. ¹⁵

In current school-based STI screening models, an offer is made to students of screening services they are not seeking. Our findings suggest that students’ participation in these screenings is motivated more by a collective acceptance of what ‘is being offered to everybody at school’ than by a rationalization by each student over what his/her individual risk of STI is or is not. The high prevalence of chlamydia and/or gonorrhoea among students who did not perceive themselves at high risk of STI (12%) and its similarity to the prevalence among students who perceived themselves at high risk demonstrate that students’ estimation was not a reliable translation of their actual risk of STI. The New Orleans screening was offered to all students in participating schools regardless of sexual activity, symptoms of STIs or a history of STI. ⁷ This study adds that screening for STIs in schools should be offered regardless of students’ perception of their risk of STI. The consistency in adolescents’ perception of not being at high risk of STI across continents ^9–13 constitutes a strong indicator that overall, most participants in school-based screenings for chlamydia and gonorrhoea ^1–3,5,6,16 are likely to be individuals who do not perceive themselves at high risk of STI. These screening programmes should expand efforts of locating and treating sexual partners of infected students, as these partners may not grasp the level of their current risk of STI.

Students were not asked about their reasons for participating in the chlamydia and gonorrhoea screening; therefore, this study does not address the issue of why students choose to participate in school-based screenings for STIs. ¹⁷ In addition, partly because health surveys are not administered to students who do not participate in screening per our programme protocol, ^15,17 the risk perception we report may not represent that of students who did not participate. Therefore, the potentials for participation bias in school-based screenings for STIs due to self-selection of volunteers still remain, ⁴ but currently available data do not support the fact of a significant self-selection based on adolescents’ perception of being at high risk of STI.