Samkange-Zeeb et al. BMC Public Health 2011, 11:727 http://www.biomedcentral.com/1471-2458/11/727 Page 4 of 12 Records found via PubMed search (n = 465) Full-text articles assessed for eligibility (n = 25) Articles selected for review (n = 10) Excluded: not reporting on studies conducted in Europe (n = 393) Excluded: not focusing on knowledge and awareness of adolescents (n = 47) Excluded: not explicitly addressing knowledge and/or awareness of STDs or study population not clearly school- attending (n = 15) Further articles identified from perusal of reference lists of articles selected for review (n = 4) Total articles included in review (n = 14) Figure 1 Flow diagram showing selection process of articles included in the review. Face-to-face interviews were used only in the surveys by Andersson-Ellström et al. [40] and by Goodwin et al. [43] (Table 2). The study outcomes were clearly defined in all studies and the topics on which questions were posed were clearly described in all but one study. The majority of the studies also reported the individual questions posed to assess the given outcomes. In six studies the authors did not mention whether the instruments used for data collection had been pre-tested, validated, or whether the questions posed had been used in previous surveys (Table 1). Of the 9 studies which clearly reported