In recent years there has been considerable research interest in determining the prevalence of self-harm among adolescents. ^{Reference Hawton, Rodham, Evans and Weatherall1–3} This is not surprising as self-harm is a key predictor of completed suicide, ^{Reference O'Connor and Sheehy4,Reference Hawton, Houston and Shepperd5} and suicide prevention is a high priority for UK governments. ^6,7 In an attempt to identify the prevalence of self-harm among adolescents, several countries including England developed and completed the Child and Adolescent Self-harm in Europe (CASE) questionnaire. ^{Reference Hawton and Rodham8} Comparative analyses of the cross-national CASE questionnaires found that five of the countries (England, Ireland, Belgium, Norway and Australia) reported similar self-harm rates, whereas The Netherlands and Hungary reported relatively low rates. ^{Reference Hawton and Rodham8} Closer inspection of the responses to the English CASE questionnaire showed that the self-reported lifetime prevalence of self-harm among young people in England aged 15–16 years was 13.2%. The CASE questionnaires report both self-reported self-harm and self-harm that meets specific CASE study criteria. To afford direct comparison with the Scotland data presented herein, we have concentrated on the former. Given that the suicide rate in Scotland is the highest in the UK and is twice as high as that in England, ^{Reference Platt, McLean, McCollam, Blamey, Mackenzie and McDaid9,Reference Brock, Baker, Griffiths, Jackson, Fegan and Marshall10} the central aim of our study was to determine, for the first time, the prevalence of adolescent self-harm in Scotland. Scotland is of special interest because not only do England and Scotland have markedly different suicide rates, they have distinct suicide rate trends: Scotland's suicide rate has been increasing in recent decades whereas England's has been decreasing, with England last year reporting its lowest suicide rate on record. ^{Reference Platt, McLean, McCollam, Blamey, Mackenzie and McDaid9–11} The utility of such a comparative study is further highlighted by a recent study of adolescent self-harm in two neighbouring European countries: The Netherlands and Belgium. ^{Reference Portzky, De Wilde and van Heeringen12} Portzky et al, employing the CASE questionnaire, found that the adolescent self-harm rate in Belgium was markedly higher than that in The Netherlands, consistent with the countries' different suicide rates (the Belgian suicide rate is much higher than the Dutch rate). ^{Reference Portzky, De Wilde and van Heeringen12} Our second aim was to examine the factors associated with adolescent self-harm. For this purpose we modified the CASE questionnaire and included additional psychosocial factors known to be important in the aetiology of self-harm and suicidal behaviour. ^{Reference Carver and Scheier13–Reference O'Connor and Cassidy15}

Method

All secondary schools in Glasgow (west Scotland) and Stirling (central Scotland) were invited to participate in the study (45 schools). Thirteen schools agreed to participate and this yielded a representative sample in terms of school type for size, status, ethnic minorities, educational attainment and socio-economic deprivation (proportion of pupils entitled to free school meals). We recruited 29% of the target schools to the study, consistent with Hawton et al who recruited 24%. ^{Reference Hawton, Rodham, Evans and Weatherall1} Data were collected during 2006–7. All pupils were in secondary years S4 or S5 and in classes in which at least 90% of the young people were aged 15–16 years.

Results

Of the 13 participating schools, 10 were local authority/comprehensive schools and 3 were independently funded. In total, 2008 young people participated in the study: this represented approximately 80% of those eligible to participate. The main reasons for non-participation were timetable constraints (which meant that not all classes in a given school year group were able to complete the survey) and absenteeism. Consistent with the 2001 UK census, 92% of the sample were White, 5.3% were Asian, 1.5% Black and 1.2% of other ethnicity. Slightly more than half (53%) of the sample were girls (Table 1).

Table 1 Prevalence of self-harm (past year and lifetime) and serious thoughts of self-harm in the previous year

	Respondents n	Prevalence % (n)	Odds ratio (95% CI)
Past year prevalence of self-harm
Boys	917	5.1 (47)	1.00
Girls	1050	13.6 (143)	2.94 (2.09-4.14)
Alla	1967	9.7 (190)
Lifetime prevalence of self-harm
Boys	917	6.9 (63)	1.00
Girls	1050	19.9 (209)	3.37 (2.50-4.54)
Alla	1967	13.8 (272)
Serious thoughts of self-harm in past year without doing so
Boys	913	8.5 (78)	1.00
Girls	1052	19.5 (205)	2.59 (1.96-3.42)
Alla	1965	14.4 (283)

Multivariate analysis

Multivariate logistic analysis showed that the following factors were independently associated with self-harm in girls: smoking, drug use, bullying, physical abuse, worries about sexual orientation, serious boy/girlfriend problems, self-harm by family and friends and anxiety (Table 2). Optimism was also lower among girls who self-harmed. In boys, smoking, bullying, sexual orientation worries, self-harm in the family, group norms and anxiety were associated with self-harm.

Table 2 Multivariate logistic regression for lifetime prevalence of self-harm

	Girls			Boys
	Odds ratio	95% CI	P	Odds ratio	95% CI	P
Smokinga
Never	1.00			1.00
Given up	3.43	1.87-6.29	<0.001	1.73	0.52-5.72	NS
Up to 5	2.01	0.74-5.47	NS	11.00	2.87-42.18	<0.001
6-20	2.06	1.01-4.21	<0.05	7.74	2.66-22.51	<0.001
21-50	2.36	1.03-5.41	<0.05	2.65	0.32-21.97	NS
>50	1.56	0.43-5.70	NS	3.40	0.96-12.02	NS
Drug useb
No	1.00
Yes	1.95	1.19-3.18	<0.01
Bullying in schoolc
No	1.00			1.00
Yes	3.09	2.06-4.64	<0.001	2.18	1.11-4.28	<0.05
Physical abusec
No	1.00
Yes	2.15	1.02-4.53	<0.05
Sexual orientation worriesc
No	1.00			1.00
Yes	2.57	1.28-5.20	<0.01	3.82	1.53-9.50	<0.005
Serious boy/girlfriend problemsc
No	1.00
Yes	2.30	1.53-3.46	<0.001
Self-harm by friendsc
No	1.00
Yes	2.89	1.94-4.29	<0.001
Self-harm by familyc
No	1.00			1.00
Yes	2.19	1.38-3.47	<0.001	8.85	4.38-17.90	<0.001
Group normsd,e				1.15	1.04-1.28	<0.01
Optimismd	0.93	0.88-0.97	<0.005
Anxietyd	1.13	1.06-1.19	<0.001	1.17	1.07-1.27	<0.001

Discussion

Self-harm is common among adolescents in Scotland, especially among girls. Indeed, the prevalence of self-harm in Scotland is similar to that reported in England, ^{Reference Hawton, Rodham, Evans and Weatherall1} Ireland, ^{Reference Sullivan, Arensman, Keeley, Corcoran and Perry24} Belgium, ^{Reference Portzky, De Wilde and van Heeringen12} Norway, ^{Reference Ystgaard, Reinholdt, Husby and Mehlum27} Australia ^{Reference De Leo and Heller2} and the USA, ²⁸ but higher than that reported in The Netherlands ^{Reference Portzky, De Wilde and van Heeringen12} and Hungary. ^{Reference Fekete, Voros and Osvath29} Despite Scotland having the highest suicide rate in the UK, its adolescent self-harm rates do not follow this trend. Indeed, the similarity of adolescent self-harm with that in England is especially noteworthy because the suicide rate in Scotland is twice that in England. ^{Reference Platt, McLean, McCollam, Blamey, Mackenzie and McDaid9–11} The absence of an English–Scottish difference is also interesting in the light of the Belgium–Netherlands comparative study which found that their cross-national self-harm rates were consistent with their respective completed suicide rates. ^{Reference Portzky, De Wilde and van Heeringen12} Perhaps the sociocultural effects in England and Scotland are diluted because both countries are part of the UK. Future research should explore these national sociocultural effects more closely. In addition, it would be of interest to investigate further whether suicidal self-harm rates differ in Scotland and England. Indeed, it may be that the rates of medically serious self-harm (e.g. overdose) closely mirror the completed suicide rates by country, whereas non-suicidal self-harm rates do not. Alternatively, it may be that some national rates of self-destructive behaviours only begin to differ from the late teenage years onwards when such behaviours become more common. There is also a substantial number of young people (14.4%) who seriously think about self-harm but who do not do so.

We endeavoured to obtain a ‘true’ picture of the prevalence of self-harm by highlighting to respondents that we were an independent research team, by providing all respondents with an envelope in which to deposit and seal their completed questionnaire and by ensuring that the respondents completed the items in the questionnaire in different orders (such counter-balancing precluded pupils ‘checking’ how their neighbour was responding). Despite endeavouring to include as many young people as possible from the target population in the survey (80% of the target sample took part), we cannot rule out the impact of absenteeism on the prevalence of self-harm, as it is known that self-harm is more common in those who truant (therefore adjusting for truancy would increase the ‘true’ prevalence rate for self-harm). ^{Reference Bjarnason and Thorlindsson30}

Consistent with similar studies in other countries, ^{Reference Hawton, Rodham, Evans and Weatherall1,Reference De Leo and Heller2,Reference Sullivan, Arensman, Keeley, Corcoran and Perry24} the results highlight the powerful effects of social influences and therefore the need to give careful attention to the management of self-harm in schools and in young people's lives more widely. For both genders, self-harm by family and friends was strongly associated with self-harm. Although self-harm by friends did not emerge as a significant independent factor in boys, this is possibly a statistical artefact, accounted for by the variance shared with the male group norms variable (group norms are defined as the beliefs, attitudes and behaviour of male respondents' friends and peers, in this case suggesting that self-harm is desirable).

Although we cannot infer causality from a cross-sectional survey, the findings highlight a number of key factors that are independently associated with self-harm. Indeed, future research is urgently required to determine the mechanisms linking the social influence effects to self-harm. Are these influences indicative of modelling or clustering effects (two phenomena widely reported in the research literature)? ^{Reference Cheng, Hawton, Lee and Chen31,Reference Exeter and Boyle32} Indeed, the familial inter-generational transmission of suicide risk is noted elsewhere. ^{Reference Melhem, Brent, Ziegler, Iyengar, Kolko and Oquendo33} Bullying and sexual orientation worries, consistent with work in other countries, also emerged as key correlates of self-harm and their management requires urgent consideration for boys and girls. ^{Reference Brunstein Klomek, Marrocco, Kleinman, Schonfeld and Gould34,Reference Spirito and Esposito-Smythers35} Despite being associated with self-harm in both genders in the univariate analyses, it is worth highlighting that impulsivity did not emerge as a risk factor in the multivariate analysis. This is of particular importance given that more than half the sample reported that they had thought about self-harming less than an hour before doing so. Depression also did not emerge as an independent risk factor. This may be explained in part by the inclusion of optimism, as post hoc analyses suggest that the latter partially mediates the relationship between depression and self-harm. The motives for self-harm reported by the young people merit comment. Consistent with the English findings, ^{Reference Hawton, Rodham, Evans and Weatherall1} the most common motivation reported by Scottish adolescents was ‘to get relief from a terrible state of mind’ – highlighting that, for the most part, the common motives underpinning self-harm are not predominantly manipulative in nature. Almost one in four young people reported that they wanted to die. Future interview-based research could usefully explore this motive further to determine whether such young people do indeed wish to end their lives.

This is one of the first studies to investigate formally the relationship between trait optimism and self-harm. Trait optimism is broadly defined as exhibiting generalised positive expectancies for the future; optimists are characterised as having greater confidence in their ability to attain goals, being better at identifying suitable goals and being more tenacious with respect to goal pursuit. ^{Reference Carver and Scheier13,Reference O'Connor, Whyte, Fraser, Masterton, Miles and MacHale14} Indeed, school-based interventions aimed at improving optimism ought to be evaluated to determine whether they protect against self-harm among girls. In addition, the promotion of mental health, the development (and evaluation) of emotional literacy programmes and initiatives that focus on responding to bullying, physical abuse, sexual orientation worries and interpersonal problems as well as managing anxiety may offer promise. The findings of this survey could also form the basis for screening programmes to aid teachers in the identification of those at risk.