Kaess et al. BMC Public Health 2011, 11:597 http://www.biomedcentral.com/1471-2458/11/597 Table 2 Mean (SD) for the YSR scores and the gender differences with 95%-confidence intervals. YSR scales 1. Withdrawn 2. Somatic complaints 3. Anxious/depressed 4. Social problems 5. Thought problems 6. Attention problems 7. Delinquent behaviour 8. Aggressive behaviour Internalizing problems Externalizing problems YSR Total Score Female 3.36 (2.45) 3.75 (2.90) 6.78 (4.89) 1.97 (1.95) 1.59 (1.97) 4.81 (2.70) 4.21 (3.00) 8.74 (4.76) 13.34 (8.11) 12.95 (6.99) 40.33 (19.26) Male 2.66 (2.26) 2.11 (2.15) 4.40 (3.80) 2.13 (1.93) 1.31 (1.89) 4.34 (2.74) 4.79 (3.28) 8.81 (5.64) 8.92 (6.47) 13.60 (8.19) 35.35 (18.55) Total 3.01 (2.38) 2.93 (2.67) 5.59 (4.53) 2.05 (1.94) 1.45 (1.94) 4.57 (2.73) 4.50 (3.16) 8.77 (5.22) 11.12 (7.66) 13.27 (7.62) 37.82 (19.07) Gender difference 0.69 1.64 2.38 -0.16 0.27 0.47 -0.59 -0.07 4.41 -0.65 4.98 Page 4 of 7 Confidence interval 0.57 - 0.82 1.50 - 1.77 2.15 - 2.61 -0.27 - -0.06 0.17 - 0.38 0.32 - 0.61 -0.75 - -0.42 -0.34 - 0.21 4.02 - 4.80 -1.06 - -0.25 3.98 - 5.98 it can be seen that the scales anxious/depressed and delinquent behaviour have the largest odds ratios per unit of raw score (table 4). The results for suicide attempts are very similar (table 3). Here again the percentage of information explained by gender alone (model 1: 2.3%) is much smaller than the percentage explained by the YSR scales alone (model 2: 23.2%). The information explained by gender in addition to the emotional and behavioural problems is with 0.3% (model 3) again without practical relevance but statistically significant (LR-test of model 2 vs. model 3: c2(1) = 10.37, p = .0013). The lack of interaction between gender and emotional and behavioural pro- blems (LR-test of model 3 vs. model 4: c2(8) = 2.65, p = .955) indicates, that the influence of emotional and behavioural problems on the probability of suicide attempts is equal for girls and boys. Also the pattern of the regression coefficients for suicide attempts is com- parable to the one for suicidal thoughts (table 4). Discussion In the present study, the prevalence rates of suicidal behaviour, divided into the two categories “suicidal thoughts” and “suicide attempts”, were high among ado- lescent students in Germany but in line with previous epidemiological research [8]. Within the sample as a whole a considerably higher prevalence of both suicidal Table 3 Goodness of fit of the logistic regression models for suicidal thoughts and suicide attempts. Model 1. gender only 2. YSR scales only 3. gender and YSR scales 4. gender, YSR scales and their interaction suicidal suicide thoughts attempts Pseudo-R2 BIC Pseudo-R2 BIC .027 .300 .303 .305 4458 3274 3270 3329 .023 .232 .235 .236 2977 2406 2404 2470 thoughts and suicide attempts could be found in girls than in boys. These results are in line with many other authors who reported about two to four times higher rates of suicidal thoughts and suicide attempts in female than in male adolescents [6,12,31,32]. Similar findings may also occur in nonsuicidal self-harming behaviour among adolescents as Brunner and colleagues have pre- viously reported quite similar gender distributions and an important role of mediating depression for repetitive self-harm in this sample [22]. Such similarities might be of interest for the ongoing discussion if self-harming and suicidal behaviour are both on the same continuum of self-destructive behaviour. Concerning emotional and behavioural problems as indicators for an existing psychopathology, female stu- dents showed higher levels of internalizing problems whereas male students tended to have slightly higher degrees of externalizing problems as assessed with the YSR. These results are not surprising as it is well known that females usually show higher rates of internalizing Table 4 Regression coefficients in their exponential form as odds ratios (OR) and their 95%-confidence intervals (CI). Coefficient suicidal thoughts OR CI suicide attempts OR CI Female gender 1.454 1.179 - 1.794 1.532 1.179 - 1.990 YSR 1: Withdrawn 1.005 0.956 - 1.057 0.961 0.905 - 1.021 YSR 2: Somatic complaints 1.049 1.012 - 1.088 1.066 1.023 - 1.111 YSR 3: Anxious/depressed 1.298 1.259 - 1.338 1.195 1.156 - 1.235 YSR 4: Social problems 0.880 0.833 - 0.929 0.885 0.828 - 0.945 YSR 5: Thought problems 1.086 1.038 - 1.137 1.062 1.010 - 1.117 YSR 6: Attention problems 0.975 0.933 - 1.019 1.018 0.966 - 1.073 YSR 7: Delinquent behaviour 1.210 1.168 - 1.253 1.171 1.125 - 1.218 YSR 8: Aggressive behaviour 0.982 0.960 - 1.005 1.009 0.982 - 1.036 OR are presented for the models with the best fit for suicidal thoughts and suicide attempts (model 3 for both). For the YSR scales the OR is the ratio of the odds for one point of increase in the raw score.