239Suicide and Life-Threatening Behavior 35(3) June 2005 2005 The American Association of Suicidology

The Prevalence of Suicidal Phenomenain Adolescents: A Systematic Reviewof Population-Based StudiesEmma Evans, BSc (Hons), Keith Hawton, DSc, FRCPsych,Karen Rodham, PhD, C Psychol, BSc (Hons), and Jonathan Deeks, MSc

The results of a systematic review of the international literature on theprevalence of suicidal phenomena in adolescents, including the influence of surveymethod, gender, and ethnicity are reported. The literature was searched using sixelectronic databases to identify all population-based studies of self-reported sui-cidal phenomena; 128 studies were included, comprising 513,188 adolescents. Themean proportion of adolescents reporting they had attempted suicide at somepoint in their lives was 9.7% (95% CI, 8.5–10.9), and 29.9% (95% CI, 26.1–33.8)of adolescents said they had thought about suicide at some point. Females weresignificantly more likely than males to report most suicidal phenomena. A lowerprevalence of some suicidal phenomena was found for Asian populations. Theprevalence of suicidal phenomena varied depending on the terminology used andtended to be higher in studies employing anonymous questionnaires than in stud-ies employing non-anonymous methods (questionnaires or interviews), althoughmost of these differences were not statistically significant.

Suicide and attempted suicide have increased intentions (Bancroft et al., 1979; Hjemelandet al., 2002; O’Carroll, Berman, Maris, Mos-in young people over recent decades (Centers

for Disease Control and Prevention, 1995; cicki, Tanney, & Silverman, 1996), especiallyin adolescents (Hawton, Fagg, Marsack, &World Health Organization, 2002). Attempted

suicide is most common in 15–24 year olds, Wells, 1982), the term deliberate self-harm isincreasingly used in Europe to denote anyespecially young females (Schmidtke et al.,

1996). Because many acts of deliberate self- nonfatal acts of self-harm, irrespective of theintention. In this paper, the term suicidal phe-poisoning or self-injury involve nonsuicidal

Ms. Emma Evans is a trainee Clinical Psychologist, University of Oxford. Professor Keith Haw-ton is Director of the Centre for Suicide Research, University of Oxford. Dr. Karen Rodham is Direc-tor of Studies of the Masters in Health Psychology at the University of Bath. Jonathan Deeks is aSenior Medical Statistician in the Centre for Statistics in Medicine, University of Oxford.

This review was conducted as part of a larger study on deliberate self-harm and associated factorsin adolescents which was funded by the Community Fund. Keith Hawton is also supported by Oxford-shire Mental Healthcare Trust. Madelyn Gould and George Patton reviewed the list of references identi-fied through the literature search. We thank Samaritans for their support and advice, Lindsay Noll andSue Mulholland for secretarial support, and Sue Simkin for her comments on previous drafts of thispaper. We are also very grateful to those who assisted with the translation of journal articles.

Address correspondence to Professor Keith Hawton, Centre for Suicide Research, Department ofPsychiatry, University of Oxford, Warneford Hospital, Oxford OX3 7JX, UK.

240 Suicidal Prevalence in Adolescents: Systematic Review

nomena will be used as an umbrella term in- adolescents. De Wilde and Kienhorst (1994)reviewed community-based studies conductedcorporating attempted suicide, deliberate self-

harm, suicidal thoughts, and suicide plans in The Netherlands. The average prevalenceof lifetime suicide attempts was 2.2%. Saferand threats.

Evidence regarding the prevalence of (1997) reviewed many of the worldwide stud-ies of suicidal phenomena in adolescents andnonfatal suicidal phenomena in adolescents

usually comes from three main sources: (a) found that a median of 10% of American ad-olescents had made a suicide attempt, consid-historical information from psychiatric sam-

ples, (b) hospital admissions, and (c) general erably higher than the figure reported by deWilde and Kienhorst. In de Wilde and Kien-population or epidemiological surveys. While

all three sources provide valuable evidence horst’s review two of the characteristics foundto be associated with prevalence were anonym-on the problem of suicidal behavior in ado-

lescents, the prevalence of suicidal phenom- ity (substantially higher rates were found inanonymous studies compared with non-anon-ena will be underestimated and a distorted

picture of the population provided if infor- ymous studies) and terminology (higher rateswere found in studies that used the phrasemation on prevalence is based solely on hos-

pital admissions or psychiatric samples. For “ending your life” than in studies that used thephrase “attempted suicide”). Moscicki (1989),example, many adolescents who present to

general hospitals with deliberate self-harm who conducted a review of community-basedstudies of suicidal phenomena in adults, andreport previous episodes for which they did

not receive medical attention (Hawton, Fagg, Safer, both reported that many differences infindings between studies can be attributed to& Simkin, 1996). Also, school-based studies

have indicated that a minority of those re- differences in methodology, supporting deWilde and Kienhorst’s conclusions.porting a suicide attempt have received medi-

cal attention as a result (Choquet & Ledoux, Both of the previous reviews of popu-lation-based studies of adolescents were,1994; Grunbaum et al., 2000; Kann et al.,

1998; Pearce & Martin, 1993). Also, hospital- however, somewhat limited. De Wilde andKienhorst’s review focused solely on the re-based studies are likely to only include individ-

uals toward the extreme end of the continuum sults of studies in one country (The Nether-lands), and Safer’s review did not includeof suicidal behavior. Studies of psychiatric

samples are likely to be even more biased. non-English language publications and wasrestricted to studies reported in the medicalTherefore population studies will provide the

most accurate information on the prevalence literature (Medline and Index Medicus). Asmany community-based studies are conductedof suicidal phenomena.

Despite a relatively large number of within schools, some may be reported in edu-cational research literature. A further reasonpopulation-based studies, the evidence con-

cerning the prevalence of suicidal ideas and for a new review is that because of a growingawareness of suicidal phenomena in the young,behaviors in adolescents in general popula-

tion samples is contradictory. Most popula- considerable further research has been con-ducted in the past few years which would nottion-based studies have been carried out in

the United States and Europe but there is lit- have been included in either of the earlier re-views.tle consistency even from studies within the

same continent. In the U.S., for example, the We present here the results of a sys-tematic review of the world literature con-lifetime prevalence of attempted suicide has

been reported to be as low as 3% (Lewis et cerning studies of suicidal phenomena inyoung people in the general population. Weal., 1988) and as high as 30% (Dinges &

Duong-Tran, 1994), although the latter fig- provide an overview of the prevalence ratesreported in these studies and consider the in-ure was from a study of indigenous people.

We are aware of two reviews of popu- fluence of the survey methods, gender, andethnicity on the findings.lation-based studies of suicidal phenomena in

Evans et al. 241

METHODS not included in this review. More seriousthoughts were categorized into three groups:suicidal thoughts, suicide plans, and suicideIdentification of Relevant Trialsthreats. (While actual self-harm and suicideattempts were categorized separately as theyA literature search was carried out us-

ing the following databases (dates covered): are likely to represent different points on acontinuum of suicidal phenomena, suicidalPsychLit (1971 to December 2000), Medline

(1966 to December 2000), EMBASE (1980 thoughts and thoughts of suicide were notconsidered to differ greatly from each otherto December 2000), Sociological Abstracts

(CSA; 1963 to December 2000), ERIC (1966 in seriousness so were considered together).For the purpose of this review, the timeto December 2000), the Australian Education

Index (1978 to December 2000), and the frames were categorized as follows: lifetime(greater than 1 year); previous year (12 monthsBritish Education Index (1976 to December

2000). The search terminology was as follows prior to the survey); previous 6 months (6months prior to the survey); previous month(* indicates truncation): (suicid* or parasui-

cid* or overdos* or self-harm* or self-cut* or (1 month prior to the survey); and recent (upto, but not including, 1 month prior to theself-poison* or self-injur*) AND (youth or

adolescen* or school or teen* or child*) AND survey). Studies were categorized into thefollowing three groups according to the sur-(survey or questionnaire or interview).vey methods used: anonymous questionnairesurveys, non-anonymous questionnaire sur-Inclusion Criteriaveys, and interview surveys. In cases whereauthors did not state whether their question-Studies were included in the review if

they met the following criteria: the study naire was anonymous or not it was assumedthat it was not anonymous. In grouping stud-sample was population-based; the majority

(90% or over) of the participants were aged ies by ethnicity of participants, at least 80%of the sample had to be of the ethnic groupbetween 12 and 20 years (inclusive); study

participants had answered either a self-report being investigated in order to be included.questionnaire about suicidal phenomena, oranswered similar questions presented at in- Statistical Methodsterview; and prevalence figures for suicidalphenomena were reported. Estimates of the average prevalence of

suicidal phenomena were calculated usingmethods of meta-analysis which attributedGrouping of Studiesweight to each study in proportion to itssample size. Variation of study estimates be-Studies were grouped according to sui-

cidal phenomena investigated, the time frame yond that expected by chance was assessed byCochran’s test of homogeneity; an estimatecovered, and the survey methods employed.

With regard to actual behaviors, we catego- of between-study heterogeneity was incor-porated into the meta-analyses using Der-rized the studies into two groups: attempted

suicide (death was the intended outcome of Simonian and Laird’s random effects ap-proach (Deeks, Altman, & Bradburn, 2001).the behavior; e.g., “tried to kill yourself,” and

“attempted suicide”); and deliberate self- The statistic tau is the standard deviation ofthe prevalences observed in the differentharm (death was not necessarily the intended

outcome; e.g., “tried to hurt or kill your- studies beyond the variation attributable tothe play of chance. Results are reported usingself ”). With regard to suicidal thoughts, ca-

sual thoughts of suicide, for example “thought 95% confidence intervals.Factors affecting prevalence were in-about death or dying” (Andrews & Lewin-

sohn, 1992), were not considered as indica- vestigated in two separate ways. First, wherethe focus was on differences between studiestive of suicidal tendencies and were therefore

242 Suicidal Prevalence in Adolescents: Systematic Review

(such as according to questionnaire method- America. Most other studies were conductedeither in Europe (n = 32, 25.0%) or Austra-ology), meta-regression was used to compare

estimates between groups of studies (Thomp- lia/New Zealand (n = 12, 9.4%). Very fewstudies were conducted in other regions suchson & Higgins, 2002). Second, where the fo-

cus was on differences between groups within as Asia (n = 4), South/Central America andMexico (n = 2), and Africa (n = 1).studies (such as between males and females),

prevalence ratios were computed for each Of all the categories of suicidal phe-nomena, a life-time suicide attempt was thestudy and averaged across studies using

methods for meta-analysis of risk ratios most frequently investigated. Previous yearsuicide attempts, and lifetime, previous year,(Deeks et al., 2001).and current suicidal thoughts, were also in-vestigated in a relatively large number ofstudies compared with other suicidal phe-RESULTSnomena.

The Nature of the StudiesPrevalence of Suicidal Phenomena

One-hundred-and-twenty-eight stud-ies presented in 124 reports were identified Suicidal thoughts and behaviors are

relatively common in adolescents in the gen-through the search strategy as eligible for in-clusion in the review (full list available from eral population. Where results were available

for three or more studies, estimates of preva-authors). Four reports included separate re-sults for subgroups of the sample. These lence were significantly heterogeneous. The

degree to which they varied between studieswere included as different studies. Where re-sults of a study were reported in more than is indicated by the value tau in Table 1, which

was highest for life-time suicidal threats andone publication, data were extracted from theearliest publication, or, in cases of longitudi- all suicidal thoughts. The mean proportion

of adolescents reporting that they had en-nal studies, from the publication in which themedian age of the study population was clos- gaged in suicide attempts (e.g., “attempted

suicide”) at some point in their lives wasest to 16 years old (the middle age in the ageinclusion criterion). 9.7% (95% CI, 8.5–10.9), with 6.4% (95%

CI, 5.4–7.5) reporting that they had engagedThe 128 studies included in this reviewcomprised 513,188 adolescents. The mean in suicide attempts in the previous year. The

proportions of adolescents who reported en-number of participants per study was 4,009,with the smallest study including only 63 ad- gaging in deliberate self-harm at some point

in their lives and within the previous yearolescents and the largest 96,116 adolescents.The median number of participants per study were higher than that reported for the equiv-

alent time frames for suicide attempts: awas 1,016, indicating that most studies tendedto be relatively small. In 116 of the studies, mean of 13.2% (95% CI, 8.1–18.3) reported

engaging in deliberate self-harm at someinformation was provided on the proportionof each gender in the samples. Overall, there point in their lifetime and 26% (CI unesti-

mable) within the previous year (there werewere similar proportions of females and males(49.7% and 50.3%, respectively). The mean only two studies in the latter category).

The mean proportion of adolescentsage of the samples was reported in only 47studies; it was 15.7 years. reporting that they had thought about suicide

at some point in their lives was 29.9% (95%Most of the studies were school-based(n = 106, 82.8%). The remainder were either CI, 26.1–33.8), with 19.3% (95% CI, 11.7–

27.0) having had such thoughts in the previ-community-based (n = 18, 14.1%) or it wasunclear how the study sample was selected ous year. The proportion of adolescents who

reported having made suicide plans and(n = 4, 3.1%). The majority of the studies(n = 77, 60.2%) were conducted in North threats was lower than the proportion who

Evans et al. 243

TABLE 1The Prevalence of Suicidal Phenomena by Category and Timeframe

Number Mean Prevalence %of Studies (95% CI) Tau1 Range %

Suicide attemptsLifetime 60 9.7 ( 8.5 to 10.9) 4.5 2–30Previous year 31 6.4 ( 5.4 to 7.5) 3.2 1–17Previous 6 months 8 7.0 ( 4.5 to 9.4) 3.2 1–17Previous month 3 6.3 ( 0.7 to 12.0) 4.5 2–9Recent 1 4 (—) —

Deliberate self-harmLifetime 7 13.2 ( 8.1 to 18.3) 6.3 4–30Previous year 2 26 (—) — 20–32Previous 6 months 10 11.2 ( 7.9 to 14.4) 4.5 2–30Previous month 0 — — —Recent 0 — — —

Suicide planLifetime 13 15.6 (10.9 to 20.3) 8.4 5–38Previous year 11 12.4 ( 8.8 to 15.9) 5.5 1–19Previous 6 months 2 30 (—) — 16–44Previous month 1 14 (—) — —Recent 1 6 (—) — —

Suicide threatLifetime 4 25.3 ( 0 to 50.8) 26.1 9–60Previous year 1 12 (—) — —Previous 6 months 2 8 (—) — 3–13Previous month 0 — — —Recent 0 — — —

Suicidal thoughtsLifetime 29 29.9 (26.1 to 33.8) 10.5 8–70Previous year 9 19.3 (11.7 to 27.0) 11.8 3–35Previous 6 months 11 17.0 (12.0 to 22.0) 8.4 4–34Previous month 7 30.7 (16.9 to 44.6) 17.3 12–55Recent 13 21.3 (16.0 to 26.6) 8.9 8–40

1Tau is the standard deviation of the prevalences in the different studiesbeyond the variation attributable to the play of chance.

reported having had suicidal thoughts (see year prevalence of deliberate self-harm wasgreater than the mean lifetime prevalence ofTable 1).

There was considerable within-group deliberate self-harm. This probably reflectsdifferences in methodology and characteris-variation beyond that expected by chance in

the proportion of adolescents reporting sui- tics of the samples, particularly for categorieswith few studies.cide attempts and thoughts. For example, the

proportion reporting lifetime suicide attempts Higher rates of suicidal phenomenawere generally found in studies from Northvaried between 2% and 30%, and the pro-

portion reporting lifetime suicidal thoughts America compared with those from Euro-pean countries. For example, the mean fig-varied between 8% and 70%. In addition,

there were some unexpected between-group ures for suicide attempts in the previous yearand lifetime were 12.6% and 7.7%, respec-findings in the prevalence of some suicide

phenomena. For example, the mean previous tively, for North American studies (z = 3.39,

244 Suicidal Prevalence in Adolescents: Systematic Review

p = 0.001), and 6.9% and 2.0%, respectively, the prevalence of suicide attempts (lifetime,previous year, and previous 6 months) andfor European studies (z = 3.27, p = 0.001).suicidal thoughts (lifetime and recent) (Table

Comparison of the Results by Gender 3). Compared to White adolescents, theprevalence of lifetime suicide attempts and

The prevalence of suicidal phenomena suicidal ideation was significantly lower forwas reported separately for males and females Asian adolescents, but significantly higher forin 88 out of the 128 studies. In the vast ma- recent suicidal ideation; however, each ofjority of studies the prevalence was signifi- these comparisons included only single stud-cantly higher for females than males. Meta- ies of Asian adolescents. The prevalence ofanalyses comparing the prevalence in females suicidal phenomena for White and Nativewith the prevalence in males were conducted American adolescents was approximately equalfor 14 categories of suicidal phenomena. The and no significant differences were found be-prevalence of suicidal thoughts and behaviors tween these two ethnic groups. The preva-was significantly higher for females compared lence of recent suicidal ideation appeared toto males in 11 of these (Table 2). The rates be lower in Hispanic adolescents than Whiteof suicidal thoughts and behaviors in females adolescents.were at least 1.25 times higher than those inmales, and, for suicide attempts in the previ- Comparison of the Resultsous year, the rate in females was more than by Survey Methodtwice that in males.

In 65 studies (50.8%) a non-anony-Comparison of the Results by Ethnicitymous questionnaire survey was used. Anony-mous questionnaire surveys were used in 51Meta-analyses were conducted to in-

vestigate differences according to ethnicity in (39.8%) studies and interviews in 11 (8.6%)

TABLE 2Meta-Analysis of Gender Differences in the Prevalence of SuicidalPhenomena: Within-Study Comparisons

Number Risk ratio,Group of studies F:M (95% CI) p

Suicide attemptsLifetime 33 1.78 (1.65 to 1.93) <0.001Previous year 14 2.08 (1.86 to 2.32) <0.001Previous 6 months 4 1.32 (0.95 to 1.85) 0.09Previous month 2 1.26 (0.45 to 3.54) 0.7

Deliberate self-harmLifetime 3 1.25 (0.97 to 1.61) 0.09Previous 6 months 3 1.59 (1.13 to 2.25) 0.008

Suicide PlanLifetime 2 1.64 (1.28 to 2.11) <0.001Previous year 5 1.58 (1.50 to 1.67) <0.001

Suicidal threatsLifetime 3 2.81 (2.07 to 3.82) <0.001

Suicidal thoughtsLifetime 11 1.38 (1.18 to 1.62) <0.001Previous year 4 1.57 (1.36 to 1.82) <0.001Previous 6 months 4 1.50 (1.24 to 1.83) <0.001Previous month 2 1.59 (1.43 to 1.77) <0.001Recent 6 1.55 (1.31 to 1.83) <0.001

TABLE3

ComparisonofthePrevalenceofSuicidalPhenomenafromStudieswhichConsistedAlmostEntirely(≥80%)ofOneEthnicGroup

EthnicGroup

White

Asian

Black

Hispanic

NativeAmerican

Number

Prevalence%

Number

Prevalence%

Number

Prevalence%

Number

Prevalence%

Number

Prevalence%

ofstudies

(95%

CI)

ofstudies

(95%

CI)

ofstudies

(95%

CI)

ofstudies

(95%

CI)

ofstudies

(95%

CI)

Suicideattempts

Lifetime

99.7%

13.0%

0—

0—

77.8%

(6.0,13.4)

(1.0,5.0)

(4.9,10.6)

Previousyear

58.4%

0—

0—

0—

210.0%

(5.1,11.8)

(0,21.3)

Previous6months

0—

11.4%

0—

0—

37.6%

(0.2,2.6)

(3.2,11.9)

Suicidalideation

Lifetime

628.4%

112.0%

0—

0—

127.1%

(16.5,40.3)

(8.2,15.8)

(26.3,27.9)

Recent

427.8%

140.0%

0—

217.4%

0—

(23.5,32.0)

(37.0,43.0)

(5.6,29.1)

246 Suicidal Prevalence in Adolescents: Systematic Review

studies. The mean and median sample sizes excluding those studies where the authorshad not indicated whether or not they werevaried significantly with methodology; means:

anonymous questionnaire studies n = 5,857; anonymous (assumed to be non-anonymous)did not markedly affect the findings.non-anonymous questionnaire studies, n =

3,104; interview studies, n = 1,143.In general, prevalence figures for sui-

cidal phenomena were higher in studies em- DISCUSSIONploying anonymous questionnaires than ininterview studies (Table 4). Within-group The results of this systematic review

confirm that suicidal thoughts and behaviorsmeta-analyses were completed for five of thecategories in order to compare the responses are relatively common in adolescents. Some

20% to 30% of adolescents reported havingfrom anonymous questionnaire surveys withthose from interview studies. No significant had suicidal thoughts, including 19% in the

year prior to being surveyed. This high prev-differences were found, but there was verylittle data from interview studies. alence suggests that such thoughts do not al-

ways reflect severe pathology. In some casesThe prevalence of suicidal phenomenafound in non-anonymous questionnaire stud- they may reflect a stage of adolescence in

which the concept of the individual’s ownies was generally lower than, or similar to,the prevalence found in anonymous question- mortality is developing. In others, suicidal

thoughts will indicate major distress and sig-naire studies. Within-group meta-analyticcomparisons were completed for 11 of the nificant risk of a suicidal act.

The findings also suggest that approxi-categories of suicide phenomena (Table 5).The prevalence figures for deliberate self- mately 10% of adolescents will have at-

tempted suicide and 13% engaged in deliber-harm in the previous 6 months and suicidalthoughts in the previous year were signifi- ate self-harm at some point (i.e., lifetime

prevalence) and 6% of adolescents will havecantly higher for studies employing anony-mous methods compared to those employing attempted suicide in a 1-year period. These

figures confirm that suicide attempts and de-non-anonymous questionnaires. The differ-ence in prevalence of suicide attempts (for all liberate self-harm are a major health issue in

adolescents. Generally, suicidal behavior ap-time-frames) between non-anonymous andanonymous questionnaire studies was small, pears to be more common in American than

in European adolescents.but larger differences were reported for othersuicidal phenomena. Repeating the analyses Both suicidal thoughts and behaviors

TABLE 4Anonymous Questionnaire Studies Versus Interview Studies

Anonymous questionnaire InterviewDifference in

Number Mean Number Mean % prevalenceCategory of studies prevalence % of studies prevalence % (95% CI) p

Suicide attemptsLifetime 23 10 9 7 −3.6 (−7.6 to 0.5) 0.09Previous year 16 8 4 3 −2.7 (−7.6 to 2.2) 0.3

Suicide planLifetime 6 14 2 17 2.8 (−13.9 to 19.6) 0.7Previous year 8 14 2 6 −8.0 (−16.7 to 0.7) 0.07

Suicidal ideationLifetime 16 33 3 30 −3.2 (−23.5 to 17.1) 0.8

Evans et al. 247

TABLE 5Anonymous Questionnaire Studies Versus Non-Anonymous Questionnaire Studies

Anonymous Non-AnonymousQuestionnaire Questionnaire

Number Mean Number Mean Difference inCategory of studies prevalence % of studies prevalence % % prevalence p

Suicide attemptsLifetime 23 10 27 10 −0.2 ( −3.2 to 2.9) 0.9Previous year 16 8 11 6 −1.8 ( −4.6 to 1.0) 0.2Previous 6 months 2 7 6 7 −0.3 ( −6.6 to 6.0) 0.9

Deliberate self-harmLifetime 4 16 2 12 −4.9 (−24.6 to 14.8) 0.6Previous 6 months 2 32 8 8 −18.3 (−21.8 to −14.8) <0.001

Suicide PlanLifetime 6 14 5 17 3.3 ( −8.9 to 15.4) 0.6

Suicide ThreatLifetime 2 38 2 13 −24.5 (−73.2 to 24.1) 0.3

Suicidal thoughtsLifetime 16 33 10 26 −6.3 (−19.2 to 6.7) 0.3Previous year 2 33 6 17 −16.2 (−24.1 to −8.4) <0.001Previous 6 months 2 33 8 16 −7.1 (−24.7 to 10.4) 0.4Previous month 3 37 2 30 −7.4 (−32.7 to 17.8) 0.6

are clearly more common in females than for self-harm and are therefore more likelyto receive medical attention (Cantor, 2000;males—the results from almost every study

included in this review showed this gender Choquet & Ledoux, 1994; Kann et al., 2000).Overall, there appeared to be lowerdifference. This is in keeping with the find-

ings from studies of hospital admissions rates of suicidal phenomena in Asian adoles-cents than in other adolescents. No other sig-(Hawton et al., 2003; Piacentini et al., 1995).

Much research on prevalence of adolescent nificant ethnic differences were found. Whilesuicidal behavior and thoughts appeared tononfatal suicidal behavior has been based on

hospital presentations. It is clear that such be slightly less common in Hispanic adoles-cents, studies from the United States thatstudies are likely to substantially underesti-

mate the true rate of deliberate self-harm. have specifically examined differences in theprevalence of suicidal phenomena by ethnicThe findings from general population studies

in which information has been obtained on group have consistently found that the preva-lence is higher for Hispanic adolescents com-whether or not self-reported acts of deliber-

ate self-harm or attempted suicide result in pared to White adolescents (Brindis et al.,1995; Kann et al., 1998; Kann et al., 2000;hospital presentation suggest that at least

three or four times as many adolescents en- Roberts, Chen, & Roberts, 1997). In thestudies included in this review, 80% or moregage in deliberate self-harm compared to the

numbers who receive medical attention as a of the sample had to be of one ethnic groupand therefore it is unlikely that they wouldresult of the acts (Choquet & Ledoux, 1994;

Kann et al., 2000; Pearce & Martin, 1993). be a minority group within the communityin which they were living. In studies whichThe underestimation of overall prevalence of

deliberate self-harm in hospital-based studies investigated ethnic differences within sam-ples, Hispanics were usually a minority eth-may be greater for females than males be-

cause males select more dangerous methods nic group (Kann et al., 1998; Kann et al.,

248 Suicidal Prevalence in Adolescents: Systematic Review

2000). Neeleman and Wessely (1999) re- There was some support for an associ-ation between survey methods and the ratesported that “minority suicide rates are higher

in areas where minority groups are smaller” of suicidal phenomena in that a larger pro-portion of adolescents gave positive responsesand the ethnic differences in our review,

which apparently contradict the findings of to anonymous questionnaires than wherenon-anonymous survey methods were em-some American studies, suggest that His-

panic adolescents may be particularly vulner- ployed, although this was only statisticallysignificant for deliberate self-harm in theable when they are a minority group. Fur-

thermore, in the Youth Risk Behavior previous 6 months and suicidal thoughts inthe previous year. It has been argued thatSurveys in the U.S., the most extreme differ-

ences in prevalence of suicidal phenomena anonymous methods are particularly suitedto collecting sensitive data and that somewere generally between Black and Hispanic

youths (Kann et al., 1996). people who would admit to suicidal thoughtsor behaviors anonymously would not do so ifThe prevalence of “deliberate self-

harm” in this review was consistently higher such an admission would lead to them beingidentified (de Wilde & Kienhorst, 1995; Safer,than the prevalence of “attempted suicide.”

This is to be expected as deliberate self-harm 1997; Shochet & O’Gorman, 1995). Thefindings of this review provide some supportincludes acts with nonsuicidal motivation as

well as those involving suicidal intent (Ban- for this.Establishing accurate prevalence fig-croft et al., 1979). It also supports the find-

ings of previous reviews in which prevalence ures for suicidal and related phenomena isimportant for several reasons. These includehas reflected the terminology used in surveys

(de Wilde, 2000; de Wilde & Kienhorst, establishing the size of the problem, examin-ing trends in prevalence, identifying risk fac-1994; Safer, 1997). There was considerable

variation between the studies in the methods tors, and providing a basis for preventionprograms. In addition to demonstrating theused to assess the prevalence of suicidal phe-

nomena. In many studies the exact terminol- extent of suicidal phenomena in adolescentsat an international level, the findings of thisogy employed in a survey or interview was

not specified. Researchers should also be review have identified some of the importantmethodological factors that may influencemindful of whether their questions will assess

the prevalence of the suicidal phenomena the results of such investigations. These par-ticularly include consistent and careful use ofthat they are interested in. Furthermore, in

most studies a clear description of what is terminology; asking adolescents to describesuicidal acts; use of clear time frames; inclu-meant by “attempted suicide” or “self-harm”

was not given and therefore the adolescents’ sion of sufficient numbers of subjects toachieve reliable results; studying the preva-interpretation must be relied on (de Wilde,

2000). Probably the best approach is to get lence of suicidal phenomena according tospecific subgroups defined by factors such asthe adolescents to describe their acts and

then apply pre-determined criteria to them ethnicity; and making careful comparisonswith the results of studies using similar meth-to determine which ones meet the research-

ers’ definition (Hawton, Rodham, Evans, & odology.Weatherall, 2002).

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