From DEPARTMENT OF PUBLIC HEALTH SCIENCES Division of Applied Public Health Karolinska Institutet, Stockholm, Sweden Self-inflicted injury among adolescents and young adults – the role of ethnicity, socioeconomic conditions and school performance

Background: Over the past ten years, the number of hospitalisations due to selfinflicted injury has increased significantly among young people in Sweden. The underlying causes are often both psychological and social. Whilst the great deal of research into SII in youth has focused upon psychological factors, the influence of the social ones has been investigated to a lesser extent. The general picture is that females, ethnic minorities, and youth from less favorable socioeconomic background appear to be particularly at risk. Furthermore, increasing empirical evidence is emerging for the important role of school performance. Aim: The overall aim of this thesis is to investigate the role of ethnicity, socioeconomic conditions and school performance, both at an individual and school level, on the risk of hospitalization due to SII among youth in Sweden. Since these factors, most probably, do not operate in isolation from each other, we aimed to study how they are interrelated in their effects on risk of SII. Study I aimed to examine socioeconomic factors as confounders of the association between ethnicity and risk of hospital admission due to SII among youth Study II aimed to examine whether the grade point average when leaving compulsory school predict hospital admission because of SII among youth Study III aimed to investigate the impact of parental SES on youths‘ risk of hospital admission because of SII and whether this influence is mediated or/and moderated by a subjects` school performance Study IV aimed to examine how both individual-level factors and school composition are related to an individual-level risk of SII, as well as to assess interactions effects between individual-level and school composition-level factors (cross-level effects) Method: All four studies are based on data from the national registers of the Swedish National Board of Health and Welfare and Statistics Sweden comprising information about socioeconomic and health indicators of the entire Swedish population. The study population consisted of the entire Swedish population born between 1973 and 1982 (N=1 009 157) and between 1973 and 1977 (N=491 258) residing in Sweden according to the Swedish Population and Housing Census of 1985 or 1990. The outcome variable—hospital admission at least once due to SII was obtained through individual records linkage to the National Hospital Discharge Register. Information about country of birth of the individuals in the study population and their parents was obtained from the Register of the Total Population. Socioeconomic variables were created by linkage to: The Swedish Population and Housing Census 1985 and 1990. School performance indicator, grade point average at the time of leaving compulsory school was created by linkage to The National School Register. Results: Ethnic minorities in Sweden (except those from Southern Europe) had an increased risk of SII as compared with the native population (HRs ranged between 1.6 and 2.3). When socioeconomic conditions were also adjusted for, however, the risks decreased for all ethnic minorities, but remained significantly higher for immigrants from Finland, Western Europe/other Western countries and those in the mixed group. School performance in compulsory school clearly emerged as an important independent predictor of SII [HRs ranged between 1.4 (for GPA=M+1SD) and 6.2 for GPA=(<M1SD)]. School performance appeared not only as an independent predictor of SII but also as a mediator between parental SES and SII and accounted for as much as 60% of the variance. The risk of SII varied significantly between schools. Individuals who attended schools characterized by a higher proportion of students with low parental SES and single-parent households had a small, but statistically significant excess risk of SII, above and beyond individual background. School-level factors, however, explained less than 1% of student‘s risk of SII. Conclusions: The increased risk for SII among youth in non-Western ethnic minorities in Sweden seems to be explained mainly by socioeconomic factors. School performance is an important mediator through which low parental SES translates into risk of SII and poor school performance should be considered as a warning sign for increased risk of SII among young people. School-level factors explain only a small percentage of student‘s risk of SII, indicating that the differences in SII mainly seem to be due to individual characteristics. LIST OF PUBLICATIONS This thesis is based on the following papers, which will be referred to in the text by their Roman numerals: I. Jablonska B. , Lindberg L. , Lindblad F. , Hjern A. (2009). Ethnicity, socioeconomic status and self-harm in Swedish youth – a national cohort study. Psychological Medicine, 39, 87-94. II. Jablonska B. , Lindberg L. , Lindblad F. , Rasmussen F. , Östberg V. , Hjern A. (2009). School performance and hospital admissions due to self-inflicted injury: a Swedish national cohort study. International Journal of Epidemiology, 38, 1334-1341. III. Jablonska B. , Lindblad F. , Östberg V. , Lindberg L. , Rasmussen F. , Hjern A. Parental socioeconomic status and self-inflicted injury – the mediating and moderating role of school performance (manuscript). IV. Jablonska B. , Östberg V. , Hjern A. , Lindberg L. , Rasmussen F. , Modin B. School effect on risk of self-inflicted injury – a multilevel study (manuscript). CONTENTS