Comparison of the results with existing epidemiological data
The 12-month prevalence of direct self-injurious behavior in this representative sample of adolescents with a mean age of 15 years was 17.8%. This rate falls in between the rates from German data presented by Plener et al.  of 19.8% and Brunner et al.  of 14.9%. The rate we identified is close to the pooled rate from 52 international studies of 19.0% for the 12-month prevalence for NSSI . As in many studies reported before, the rate for female adolescents was substantially higher – more than 5 times higher in our study – than for male adolescents [39, 40]. In their meta-analysis of 120 studies, Bresin & Schoenleber  concluded that, across age groups, women are more like to engage in NSSI (weighted average Odds Ratio 1.5) and that the effect of sex differences is larger in clinical samples (OR 2.25) than in community samples in adults.
In this study, 15.4% of the adolescents reported that they had engaged in suicidal ideation “sometimes” or “often” in their lifetime. This finding is in line with Brunner et al.’s  finding of 14.4% in German adolescents. A total of 36.3% reported that they had ever had suicidal thoughts in their lifetime – about 3% less than reported in the representative German data from 2007 (39.4%) . The finding that about one third of all adolescents had ever had suicidal thoughts in their lifetime corresponds with the range of rates reported by cross-national WHO studies peaking at 37.9% . Just as Kaess et al.  showed, we found a clear sex difference with a rate for suicidal ideation that was 2 times higher in female than in male adolescents. Although a recent study in Asia with adolescents and young adults from Malaysia reported a higher rate of suicidal ideation in male individuals , there has also been clear support for a higher prevalence in female individuals in other studies [17, 43, 44]. It is possible that the picture in the literature is not clear because there are different sex-specific age peaks in the frequency of suicidal ideation, and thus, results might depend on the mean age of the samples that have been examined. While the prevalence of suicidal ideation appears to peak during mid-adolescence in female adolescents, male adolescents seem to show it in late adolescence instead . Thus, the reason the prevalence rate was higher in female adolescents in our study may have been because the mean age of our sample was 14.9 years.
In our study, 7.6% of the sample reported that they had attempted suicide at least once in their lifetime. This percentage is very close to the results from other representative German studies of adolescents that reported 8.0% , 9.0% , or 6.5% . The prevalence rate in Germany consistently appears to be lower than the European average of 10.5% . Our result is also comparable to prevalence rates that were based on representative data from the US of adolescents and is also within the reported ranges from pooled international prevalence data . Again, in our data, the prevalence rates for female adolescents were clearly (about 3 times) higher than for male adolescents. A prevalence rate of 2 times higher for female adolescents compared with male adolescents was also reported in another study . In some countries participating in the ESPAD study, female adolescents were again found to attempt suicide at a rate that was 3 times higher than the rate for male adolescents (e.g., in Romania, Greece, or Armenia ). The European-wide OSPI project analyzed data on suicide attempts in adults in 8 countries: Gender differences were obvious in the seriousness of the suicide attempt. While actions in men were more often rated as serious suicide attempts, the acts of women were more often categorized as parasuicidal gestures . Thus, having not differentiated the seriousness of the suicide attempts in our study, it could be possible that the prevalence rates we identified for suicide attempts in female adolescents represent a larger share of parasuicidal gestures and thus a more intensive and obvious communication of distress. The difficulties involved in identifying the seriousness of an attempt were underlined by Shaffer , who argued that suicide attempts should not be hastily classified as “benign” gestures or “parasuicide.”
Comparison of the results with data reported by adolescents with a migration background
Our results concerning the higher prevalence rates in the suicide-related variables that we examined are in line with the results presented by Plener et al. . In our sample, adolescents with a migration background had a lifetime prevalence rate of 10.5% for suicide attempts, which was 1.5 times and statistically significantly higher than in German “native” adolescents. The prevalence rates in Plener et al.’s sample of adolescents who had at least one parent who was not born in Germany was 8.94% for suicide attempts with an OR of 4.45 in comparison with German adolescents without a family history of migration. A Swiss study reported that suicide attempts were not related to migration background as the outcome of a multivariate analysis. But in their descriptive data, the rates for lifetime suicide attempts were higher in adolescents with a migration background .
The results for direct self-injurious behavior pointed in the same direction. In our sample, adolescents with a migration background reported a 12-month prevalence of 19.6% for having intentionally harmed themselves, while their counterparts without a migration background reported a prevalence of 17.2% (p = .006, stat. Sign.). This goes along with Plener at al.’s study on non-suicidal self-injury where significant differences between adolescents with and without a migration background were reported: 30.08% vs. 19.16% lifetime history of NSSI .
In our sample, the frequency of suicidal ideation was also higher for adolescents with a migration background, especially concerning the category “often” (7.4% vs. 5.5%; p = .006; stat. Sign.). While the lifetime prevalence of suicidal ideation ranged from 35.9% (natives) to 37.4% (migration background) in our sample, in a Swiss adolescent sample, the 12-month prevalence ranged from 25.9% (natives) to 31.0% (migration background) . However, after controlling for covariates in a regression, migration background lowered the risk for suicidal ideation in the study by Vazsonyi et al. .
When interpreting these results, it has to be taken into account that rates of suicide attempts and suicidal ideation vary over time. This point also applies to the prevalence of these constructs in adolescents with a migration background as shown, for example, by Price & Khubchandani . Furthermore it has to be taken into account that suicide rates differ between cultures and religious background which was also reflected in our results depicting suicidal attempts and ideations.
The gender-specific analysis confirmed the general result of a higher prevalence of suicide attempts in (both female and male) adolescents with a migration background in comparison with German “natives.” For suicidal ideation, a statistically significant difference was evident in only the data for female adolescents (p = .008) but not for male adolescents with a migration background in comparison with students without a history of migration. The gender-specific analysis did not confirm statistically significant differences in direct self-injurious behavior between adolescents with or without a migration background accounting for both genders.
In looking at adults with a migration background, WHO data have revealed that for many migrant groups, a higher rate of lifetime suicide attempts is reported when compared with adults from the country they immigrated to (“adults without a migration background”). These data also describe an association between the frequency of suicide attempts and migration-specific variables – that is, being born outside the immigration country and retaining citizenship in the “homeland” in later generations (offspring) of migrants, thus pointing to possible obstacles in acculturation . The idea that the suicide attempt of an immigrant is more strongly related to situational stress factors – potentially because of a migrant’s special socio-economic and societal position – and is possibly less persistent over time was pointed out in another study : Even though immigrants are reported to have higher rates of suicide attempts, they are less likely to repeat their suicide attempt in comparison with the “native” population. However, this study again reported on adult data, and these results should not be generalized to adolescents.
Looking at the specifics of the groups with different migration backgrounds, our study revealed the following: Two groups of adolescents with a migration background (i.e., students with roots from Poland and from Southern Europe) showed the highest prevalence rates of deliberate self-harm and suicide attempts. The third highest frequency of suicide attempts was reported by adolescents stemming from predominantly Islamic countries (e.g., Lebanon, Iraq, Iran, Morocco, etc.). It is interesting that this finding is in line with results from Lipsicas et al. , who reported that migrant adults from Islamic countries displayed high suicide attempt rates despite low rates in their home countries. As mentioned above, rates vary between countries and one would expect that those variations stay constant during the migration process.
For suicidal ideation, the highest prevalence was found in adolescents with an Asian migration background (49.5%), where almost every second student reported that they had experienced suicidal ideation at least “rarely” in their lifetime. There are hints that Asian adolescents face great challenges in acculturation due to language differences, unfamiliar customs and values , and cultural differences in educational practices . One previous study reported that adolescents with an Asian migration background had higher educational aspirations than other immigrant groups . This finding was also supported by our data in that more than 54% of adolescents with Asian migration background aimed for a university entrance diploma (in comparison with 43% of native German students). Such high educational goals are connected with stress itself; additionally experiencing acculturative stress seems to be one argument that can be used to explain the high rate of suicidal ideation in this group. Again, youth with a Polish migration background reported a high lifetime frequency of suicidal ideation (47.5%) followed by adolescents with roots in Northern/Western Europe. In contrast to our study, a report from the Netherlands revealed significantly higher rates in suicidal ideation in adolescents with a Turkish migration background – significantly elevated in comparison with other migrant groups and native adolescents . In our sample, adolescents with a Turkish migration background showed lower rates of suicidal ideation than German natives and several other migrant groups.
When interpreting the results for each of the specific migration groups, it is important to consider that the distribution of gender was not exactly the same in every group. A factor that might partially account for the result for Poland, for example, could be that the number of female adolescents in the sample with a Polish background was 55.9% and thus higher than the average for the total migration sample (49.3%). Since it is known and was also shown in our study that female adolescents showed a higher prevalence of self-harm, suicidal ideation, and suicide attempts, it makes sense for the rates in the Polish-background group to be somewhat higher.
The same explanation can partially account for the relatively low prevalence rates in students with a migration background from the former Yugoslavia; the number of female adolescents in this subsample was 45.0%. However, the proportion of female students does not provide a full explanation for different prevalence rates as demonstrated by the subgroup of adolescents with an Asian background: Despite the fact that the proportion of female students was 45.4% (below average) in this group, the rate of suicidal ideation was clearly elevated in comparison with “German natives.” Also the subsample with a Turkish migration background had a slightly higher proportion of female students (52.4%) than the sample average or the German subsample, and still, the rate of lifetime suicidal ideation and the 12-month prevalence of direct self-injurious behavior were below the average of the total sample of students with a migration background and below the average of the German subsample.
The question of why adolescents with a migration background have a higher prevalence of suicidal ideation and suicide attempts can be discussed with the following hypothesis: Obviously, even second or later generation immigrants suffer from underlying acculturative stress. Lipsicas et al.  pointed out that this acculturative stress could be associated with a higher prevalence of suicidal thoughts and behaviors . There is also literature that has shown that especially in adolescents with a migration background, suicidal ideation is associated with life stress and a lack of support from parents . Parents can be a protective factor if they are supportive, if students live with both parents , and if parents show an authoritative parenting style . However, migration without parents constitutes a major risk factor  – a situation that has become more common under war-related refugee movements in recent years. It seems that the degree of cultural difference between the country or area of origin and the place of resettlement plays an important role in the extent to which “migration background” is a risk factor. When large cultural differences exist, even an internal migration within the same country can be associated with elevated rates of suicidality . Another second hypothesis could be that persons with higher rates of suicidality – be it ideations or attempts – tend to migrate more often. There is a study that showed that suicidal ideation in Mexican adolescents predicted aspirations to migrate to the US . As laid down in the introduction, there are hints in the literature that different variants of acculturation, possibly whether this is in contrast to the acculturation stage of the origin family or to discrimination experiences, might have an association with the frequency of mental symptoms and possibly also to suicidal thoughts and attempts. However, this is up to now speculation and needs to be investigated by analyzing migration specific predictors for suicidal behaviors. This has been done for other risky health behaviours like substance consumption (Donath 2016). However, literature concerning migration-specific predictors on health-related behaviors and more so on mental symptoms is scarce – also because of the necessity of combined medical and sociologic expertise.
A study of adult women with Turkish roots living in Germany assessed the rate of their suicide attempts and their motives for suicidal behavior with a qualitative design. It showed that the dominant motives for suicidal behavior were associated with the individual’s migration history or situation: Young women suffered from a lack of acceptance into German society, and middle-aged women reported isolation and a lack of self-determination . German repatriates emigrating from the former Soviet Union were also previously found to suffer from a lack of acceptance as “Germans” in German society and disillusionment after resettlement; they also showed an elevated risk for suicidality in adulthood . Thus, this would be further hints which underline a possible problematic if there is felt inconsistence between the own felt level of integration or even assimiliation and the view of this status by the others of the majority society. There is a chance that those inconsistence problems are also evident in adolescents and lead to similar risks concerning suicidal thoughts and behavior.
All data analyzed in this study relied on self-reported information. When assessing self-reported data involving personally sensitive information, there is the danger that the respondent will provide socially acceptable answers. This could be a source of bias that can lead to possible underreporting. This would imply that the real prevalence of suicidal behavior and direct self-injurious behavior is higher. However, the prevalence rates reported in the current study are in line with those reported in the literature – also based on self-reports. Thus, we have to assume that the effect size of the bias is about the same in all studies employing the survey method.
The assessment of suicide attempts was carried out with established and tested measurements corresponding to instruments that are widely used on an international level (Self-Harm Behavior Questionnaire  and Ottawa Self-Injury Inventory ). Yet, the construct of direct self-injurious behavior was assessed without the amendment “without the intention to kill yourself.” In the Ottawa Self-Injury Inventory , the wording focuses only on self-injury, without precise actions, but is in line with the focus “without the intention to kill yourself.” To investigate the construct of suicidal ideation, a deviation in scaling and the same time relation as used for the Ottawa Self-Injury Inventory  were applied. However, all three constructs were assessed with items that have been established and tested previously in representative surveys [16, 28]. We agree that the choice of instruments is crucial for providing the valid assessment of suicidal ideation and suicide attempts. Published studies have shown high agreement between the existing instruments (Self-Harm Behavior Questionnaire and Ottawa Self-Injury Inventory), which were also used in our study .
The method that we used to define migration background differs from that used in other studies, particularly in the US. In our analyses, we did not differentiate between first-generation immigrants and descendants of immigrants living in the immigration country for a second generation. But the latter situation applied to the majority of the current sample. Thus, the present results should be interpreted as accounting for second-generation immigrants. However, the definition used here is the official definition included in the national census surveys and was chosen for comparability with other representative data.
Since the scope of the study was not suicidality but delinquency and criminological research questions, further clinically interesting data such as history of diagnosed depression or psychiatric/psychotherapeutic interventions because of suicidality were not available.
Summary and outlook
To our knowledge, this is the first representative study to report data on suicidal ideation, suicide attempts, and direct self-injurious behavior in adolescents with a migration background in Germany. We compared and discussed our results in relation to one non-representative study .
The results of our study show that there is a need for the prevention of suicidality in adolescents in Germany and for culturally sensitive prevention in adolescents with a migration background – for female as well as for male adolescents. Target-group-specific prevention should focus on the themes of the target group – for migrants or other groups. There is evidence that such target-specific prevention measures are effective in migrant groups . Further research should explore the specifics of a migration background as a risk factor for suicidal ideation and behavior.