REVIEW ARTICLE |
Section of Clinical Neuropharmacology and MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Kings College London, London, UK, and Department of Psychiatry, Harvard Medical School and Psychopharmacology Program, McLean Division of Massachusetts General Hospital, Boston, Massachusetts, USA
Department of Epidemiology, Harvard School of Public Health, and Department of Psychiatry, Harvard Medical School and Psychopharmacology Program, McLean Division of Massachusetts General Hospital, Boston, Massachusetts, USA
Lucio Bini Mood Disorder Centre and Department of Psychology, University of Cagliari, Sardinia, Italy, and Department of Psychiatry, Harvard Medical School and Psychopharmacology Program, McLean Division of Massachusetts General Hospital, Boston, Massachusetts, USA
Department of Psychiatry, Harvard Medical School, Psychopharmacology Program and International Consortium for Bipolar Disorder Research, McLean Division of Massachusetts General Hospital, Boston, Massachusetts, USA
Correspondence: Dr Evangelia M. Tsapakis, MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, PO Box 80, De Crespigny Park, London SE5 8AF, UK. Email: e.tsapakis{at}iop.kcl.ac.uk
E.M.T. has received research support from Johnson & Johnson Psychiatry
Research and Development. L.T. has received research support or served as a
consultant to JDS, IFI, Eli Lilly and Janssen Pharmaceutical Corporations.
R.J.B. is a consultant to or has received research support from Janssen, IFI,
JDS, Eli Lilly, Novartis and Solvay Pharmaceutical Corporations. Funding is
detailed in the Acknowledgements.
*These authors contributed equally to the work.
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The safety of antidepressants in children and adolescents is being questioned and the efficacy of these drugs in juvenile depression remains uncertain.
Aims
To assess antidepressant efficacy in juvenile depression.
Method
Systematic review and meta-analysis of randomised controlled trials (RCTs) comparing responses to antidepressants, overall and by type, v. placebo in young people with depression.
Results
Thirty drug–placebo contrasts in RCTs lasting 8 weeks (median) involved 3069 participants (512 person-years) of average age 13.5 years. Meta-analysis yielded a modest pooled drug/placebo response rate ratio (RR=1.22, 95% CI 1.15–1.31), with little separation between antidepressant types. Findings were similar for response rate differences and corresponding number needed to treat (NNT): overall NNT=9; tricyclic antidepressants NNT=14 > serotonin reuptake inhibitors NNT=9 > other antidepressants NNT=8. Numbers needed to treat decreased with increasing age: children (NNT=21) > mixed ages (NNT=10) > adolescents (NNT=8).
Conclusions
Antidepressants of all types showed limited efficacy in juvenile depression, but fluoxetine might be more effective, especially in adolescents. Studies in children and in severely depressed, hospitalised or suicidal juvenile patients are needed, and effective, safe and readily accessible treatments for juvenile depression are urgently required.
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The first author (E.M.T.) initially screened reports for potential usefulness, identifying placebo-controlled trials involving juvenile patients diagnosed with a depressive illness and treated with antidepressants. The first and second authors (E.M.T., F.S.) then applied the following inclusion criteria independently, and reached consensus with the other authors. The criteria were:
Ultimately 29 of 304 initially screened studies met these criteria;5,19–44 Fig. 1 shows a summary of the study selection process as recommended by the Quality of Reporting of Meta-analyses (QUOROM) statement.45 All 29 studies had antidepressant and placebo arms, and one included a third arm (placebo v. SRI v. tricyclic antidepressant),38 to yield 30 drug–placebo contrasts for meta-analysis.
![]() View larger version (18K): [in a new window] [as a PowerPoint slide] |
Fig. 1 Selection process for studies to be included in the meta-analyses
reported.
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Data extraction
First author E.M.T. extracted data from reports, which were verified
independently by F.S.; discrepancies were resolved by consensus of all
authors. For studies reported more than once, we used the most complete
samples available. Information extracted included items required for
meta-analysis of efficacy rate ratios and for meta-regressions outlined below.
For continuous measures of clinical symptom rating scales we compiled a
uniform percentage scale of clinical severity (maximum possible scale score
set at 100%): for example, for the 21-item Hamilton Rating Scale for
Depression the maximum score of 68 points was taken as 100%, so that entry
scores of 20 or more were considered equivalent to percentage scores of 29.4%
or over; other scale conversions are defined below. Definitions of
treatment responder varied between studies. Adherence to
randomly assigned study medication and precise days of treatment exposures
were reported inconsistently, but the percentage of patients retained was
available for all studies.
We compared doses across agents and studies by use of standardised imipramine equivalent (IMIeq) daily doses, despite the lack of firm definitions of clinical dose–effect relationships with tricyclic antidepressants or SRIs at any age. The potency ratios selected were based on the empirical option of estimating median doses from manufacturers recommendations, textbook summaries, and clinical practice with actually employed doses for each agent, derived largely from studies and clinical experience with adults.46
Meta-analysis
Responder rate (proportion of sample attaining a
study-specified level of improvement in clinical ratings, typically at least
50% of initial ratings of depressive symptom severity) was determined for the
primary categorical outcome measure defined in each study (or that most
consistent with other trials when a primary outcome was not specified) to
distinguish responders (n) and non-responders
(N–n). Statistical analyses employed Intercooled Stata
software, version 9.2 for Windows (2006, Stata-Corp, College Station, Texas,
USA). Trial results were combined through the Stata METAN command, using
fixed-effects models to estimate pooled Cochran–Mantel–Haenszel
drug:placebo rate ratios (RRs) and rate differences (RDs) and their 95%
confidence intervals for all antidepressants combined, for each drug type
considered separately (tricyclic antidepressants 14 trials; SRIs 12 trials;
other drugs – mirtazapine, moclobemide, nefazodone – 4 trials),
and for reported age groups (adolescents 16 trials; mixed ages 10 trials;
children 4 trials). Random-effects models were also considered, based on tests
for interstudy heterogeneity in selecting the reported pooled values, as
recommended by DerSimonian &
Laird.47 A forest
plot (rate ratio for each trial and a pooled value, with 95% confidence
intervals, and symbol size proportional to study size and variance) summarised
salient results graphically (Fig.
2).
![]() View larger version (20K): [in a new window] [as a PowerPoint slide] |
Fig. 2 Forest plot of rate ratios (RR, with 95% CI) of responses to drug or
placebo in 30 randomised double-blind placebo-controlled comparisons of rates
of response to antidepressants v. placebo, with overall
pooled RR (1.22; 95% CI 1.15–1.31; blue diamond), based on
meta-analysis. Squares represent trials of serotonin reuptake inhibitors
(SRIs; 12 trials); circles represent tricyclic antidepressants (TCAs; 4
trials) and other types of antidepressants (4 trials); the size of the data
point is proportional to weight defined by study participant number and
measurement variance.
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Meta-regression
To evaluate study or participant characteristics associated with trial
outcomes, we conducted meta-regression analyses of rate ratios v. the
following study characteristics: drug type (tricyclic antidepressants
v. SRIs v. other antidepressants); sample size; publication
year; published v. unpublished; type of analysis – completer
v. last observation carried forward (LOCF); funding source
(industry-sponsored or not); exposure weeks; and estimated methodological
quality of each study based on Jadad ratings (from 1 to a high score of
4).51 Additional
patient characteristics considered were age group (children, mixed ages,
adolescents); average drug dose (approximate equivalent to imipramine in
mg/day, based on a typical daily dose of 150 mg/day for
imipramine);46
in-patient/out-patient status; and baseline illness severity (percentage of
maximum scale score required for trial entry). Variables were considered
further based on their ability to alter the estimated pooled rate ratio by
0.10 or more. Based on preliminary univariate regressions to support ranking
their effects on rate ratio, we then introduced variables into a
meta-regression model in descending rank order.
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Characteristics and quality assessment of included studies
A total of 3069 participants were represented, not counting 91
placebo-treated participants in the study by Keller et
al38
considered twice in placebo comparisons with an SRI or tricyclic
antidepressant (online Table DS1). The weighted mean participant age was 13.5
years (s.d.=0.4, median=14.5, range 6–20). Most trials with both
children and adolescents did not report response rates for each age group
separately. Only 4 studies (all involving tricyclic antidepressants)
separately considered 121 (3.9%) children aged 12 years or
less,20,21,24,27
so that randomised controlled trials of modern antidepressants involving only
or separately reported children with depression were not available. Adolescent
participants (n=1427) were considered separately in the majority of
comparisons (16 of 30 trials, 53%), representing 46.5% of all participants.
Ten other samples (33%) included both adolescents and children
(n=1521), representing 49.6% of participants. Information about
gender-specific treatment effects was not provided in most reports.
Of 30 drug–placebo comparisons considered (Table DS1), 14 involved tricyclic antidepressants, including amitriptyline, clomipramine, desipramine, imipramine and nortriptyline; 12 involved SRI-type agents, including R,S-citalopram, fluoxetine, paroxetine, sertraline and venlafaxine; 4 involved other antidepressants, including the reversible type A monoamine oxidase inhibitor (MAOI–A) moclobemide and atypical agents mirtazapine and nefazodone. One trial involved three arms, with paroxetine or imipramine v. placebo,38 and another included adolescents with depression and comorbid alcohol misuse.36
In addition to being randomised, double-blind and placebo-controlled, all trials included use of modern standardised diagnostic criteria (Research Diagnostic Criteria for major depressive disorder,52 DSM–III or later, or ICD–9/10) to diagnose clinical depression – major depressive disorder in 89.7% of cases. All studies except the earliest SRI trial25 were considered adequate with respect to randomisation and masking. Quality ratings averaged 2.97 (s.d.=0.76, median=3.0, range 1–4),51 and proportions of trials with high-quality scores (3 or 4) ranked tricyclic antidepressants (12/14 trials, 86%) > other antidepressants (3/4 trials, 75%) > SRIs (8/12 trials, 67%; online Tables DS1 and DS2). Outcomes were given for participants who completed the trials in only 6 studies;25,26,30,35,37,38 the other 23 involved LOCF-based outcomes (Table DS1). Given the scarcity of completer analyses and the possible superiority of LOCF analysis, in order to enhance consistency and maximise the sample available for analysis, the reported results are based on LOCF outcomes.
Drug doses and exposure times
All studies included provided drug doses consistent with contemporary
paediatric practice, based on body-weight-adjusted daily dosing (mg/kg)
considered standard for treating adult major depressive
disorder.46 The
overall IMIeq drug dose averaged 165 mg/day (s.d.=48). Median doses
(25th–75th percentile values) for the three major drug classes ranked
tricyclic antidepressants 200 (140–220) mg/day > other
antidepressants 178 (156–180) mg/day > SRIs 132 (106–161)
mg/day (Table DS2). By age groups, median (25th–75th percentile) doses
ranked adolescents 200 (139–212) mg/day > mixed ages 160
(102–168) mg/day > children 140 (100–144) mg/day, suggesting
similar mg/kg daily dosing.
Reported nominal trial durations yielded a weighted (by N/study) average exposure time of 8.7 weeks (median=8, range 1–12), indicating an overall trial experience of approximately 512 person-years. Withdrawal rates and actual exposure times are not described for most trials, but drug treatment averaging approximately 8 weeks should be adequate to detect antidepressant effects, at least based on studies in adult depression.46 The studies analysed included three relatively brief trials – a 5-week trial of a tricyclic antidepressant,21 another of a short-acting MAOI,34 and a 1-week trial of a tricyclic antidepressant.31 Total exposures (median) differed substantially between drug types, ranking SRIs 1584 person-weeks > other antidepressants 1000 person-weeks > tricyclic antidepressants 248 person-weeks (Table DS2). This imbalance of both exposure times and participant counts indicates major mismatching, tending to favour SRIs over tricyclic antidepressants, whereas median estimated IMIeq daily doses of SRIs were 34% lower than those of tricyclic antidepressants (Table DS2). Among age groups, median exposures ranked: adolescents and children 1148 person-weeks > children 281 person-weeks > adolescents 262 person-weeks. When both dose (IMIeq mg/day) and average exposure time (weeks) are considered together, there is no overall difference between drug types: SRIs mean=1232 mg-weeks (s.d.=269); tricyclic antidepressants mean=1239 mg-weeks (s.d.=642); other antidepressants mean=1257 mg-weeks (s.d.=339); one-way analysis of variance (ANOVA), F=0.004, d.f.=2,27, P=0.996.
Initial depression severity
We used a uniform percentage scale to represent initial illness severity
across rating methods. Maximum scores on the 21-item Hamilton Rating Scale for
Depression (HRSD; maximum score 68), the 17-item HRSD (maximum score 55), the
Montgomery–Åsberg Depression Rating Scale (maximum score 60), the
Psychiatric Rating Scale (maximum score 16), the School-Aged Depression List
Interview (maximum score 119), the Childrens Depression Rating Scale
(maximum score 63), the Childrens Depression Rating Scale –
Revised (maximum score 113) and the Children Depression Inventory (maximum
score 100) were all rated as 100%. Based on such normalised scaling, initial
illness severity ratings were similar across placebo (mean=46.4, s.d.=15.9,
median=49.9) and antidepressant (mean=47.5, s.d.=16.7, median=49.6) arms,
indicating moderate to severe intensity of baseline depressive symptoms in
most trials, all of which involved young people receiving out-patient
treatment for depression. These initial depression ratings for participants
randomised to drugs or placebo did not differ appreciably across drug types
(Table DS2).
Treatment efficacy
We defined primary outcomes for meta-analysis a priori as
responder status, based on changes in clinical ratings from intake to last
observation point (as defined in each trial) involving substantial
improvement, typically a 50% or greater reduction in symptomatic ratings of
depression on standardised scales (Table DS1). Data pertaining to other
outcomes of potential interest, including changes in continuous measures of
depression severity, rates of clinically significant improvements or syndromal
remission, and withdrawal rates, were reported too inconsistently to support
systematic analysis.
Preliminary consideration of median response rates indicated modest differences between antidepressants and placebo, averaging 10.9% overall (60.1% with antidepressants v. 49.2% with placebo), and ranging from a difference of 8.0% for SRIs to 12.3% for tricyclic antidepressants (Table DS2). These average contrasts also were similar between age groups, ranging from 8.0% in adolescents to 16.2% in children, with a plausible intermediate difference of 11.6% in mixed-age juveniles (one-way ANOVA: F =0.304, d.f.=2,27, P=0.740; not shown), suggesting greater drug response with brain maturation.
Comparative efficacy of treatment with an antidepressant v. placebo, based on responder rates (i.e. proportions), is shown for all 30 available contrasts, as response rate ratios and rate differences and their 95% confidence intervals, based on meta-analysis (Fig. 2, Table DS3). Most trials (22/30 trials, 73%) yielded rate ratios of 1.0 or above, but only 6 (20%) met the criterion that the lower limit of the confidence interval of the trial rate ratio should be >1.0, and 5 of these involved an SRI – that is, fully 80% of comparisons (24/30) failed to meet this criterion of superiority of antidepressant over placebo, reflecting small effect differences.
An estimate of pooled overall effect size, based on meta-analysis to determine a pooled rate ratio and its confidence interval for all 30 trials, yielded a value of 1.22 (95% CI 1.15–1.31), indicating moderate (22%) overall superiority of antidepressant over placebo response rate on the multiplicative scale (Fig. 2, Table 1). Preliminary testing for interstudy variance (Q)48 in this (P=0.28) and other meta-analyses (Table 1) supported use of a fixed-effects meta-analysis model. However, random effects modelling yielded a similar overall pooled rate ratio of 1.20 (95% CI 1.11–1.29).
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View this table: [in a new window] | Table 1 Meta-analytic comparisons of pooleda drug–placebo differences in response rates in subgroups in randomised trials of antidepressants for juvenile depression |
Serotonin reuptake inhibitors yielded a higher response rate ratio
(RR=1.23, 95% CI 1.14–1.33) than tricyclic antidepressants (RR=1.15, 95%
CI 0.98–1.34), but the overlapping confidence intervals indicate
statistical non-separation by drug type. Of the SRIs, in its four trials
(Table DS1) fluoxetine showed somewhat greater pooled efficacy than in eight
trials of other SRIs: respectively, RR=1.45, 95% CI 1.24–1.70, range
1.00–1.74 v. RR=1.16, 95% CI 1.06–1.27, range
0.50–1.53; rate difference RD=0.196, 95% CI 0.117–0.276
v. RD=0.083, 95% CI 0.034–0.131; NNT=5.8, 95% CI 4.0–10.8
v. NNT=12.2, 95% CI 7.7–29.4. The largest effect size for
fluoxetine was reported by March et al (RR=1.74, 95% CI
1.29–2.34),5
whereas its three remaining trials (Simeon et
al,25 RR=1.00;
Emslie et
al,30 RR=1.68;
Emslie et
al,40 RR=1.27;
Table DS3) yielded pooled effects (RR=1.32, 95% CI 1.10–1.59) similar to
other antidepressants (overall RR=1.22, 95% CI 1.15–1.31). Other types
of antidepressants tested in a small number of trials yielded a slightly
higher pooled rate ratio (RR=1.27, 95% CI 1.06–1.52) than did the SRIs
(Table 1), and again the 95%
confidence intervals overlapped, and the weighted NNT estimates confirmed such
overlap of efficacy. For all 30 trials, the NNT was 9.35 (95% CI
7.09–13.7); for tricyclic antidepressants the NNT was 14.49 (NNH 111.11
to
to NNT 6.85, to manage the rate difference in the 95% CI range
falling below zero); for SRIs the NNT was 8.85 (95% CI 6.49–13.9); and
for other types of antidepressants it was 7.81 (95% CI 4.57–27.0).
Effects of age
The three age groups yielded an interesting progression of rising pooled
rate ratio values with increasing age: children (RR=1.11, 95% CI
0.75–1.64) < juveniles of mixed ages (RR=1.19, 95% CI
1.09–1.30) < adolescents (RR=1.27, 95% CI 1.15–1.40;
Table 1), with similar
increases in rate differences and corresponding decreases of NNT by age (about
21, 10 and 8 respectively). For comparison with results from randomised
placebo-controlled trials of antidepressants in adults, we applied
meta-analysis to findings from over 250 trials involving 23 500
participants.54,55
For adults, the overall pooled, random-effects rate ratio was 1.85 (95% CI
1.67–2.04; z=12.3, P<0.001) and the overall rate
difference was 0.288 (95% CI 0.276–0.300; z=46.2,
P<0.001), with an estimated NNT of 3.5 (95% CI 3.3–3.6), and
results were similar for the different types of antidepressants (not shown).
These findings add to the impression that antidepressant efficacy may increase
with age.
Reporting bias and influence of individual trials
A funnel plot (s.e. of RR v. RR) encompassing published and
unpublished trials indicated somewhat asymmetrical distribution of individual
trial rate ratios leaning towards the positive about the pooled value of 1.22
as a function of the variance (s.e.) of individual trial RRs (RR values
>1.22 averaged 0.42, s.e.=0.47 v. <1.22 averaged 0.27, s.e.=
0.23, a 1.54-fold difference) (not shown), and in meta-regression analyses the
rate ratio was 22.0% (95% CI 1.5–41.8) higher in published v.
unpublished trials, although unadjusted Beggs (P=0.34) and
Eggers (P=0.30) tests did not indicate publication bias. We
could not determine whether additional trials failing to find superior effects
of antidepressants over placebo exist as unreported findings. Nevertheless,
the preceding observations suggest that publication might have been biased
towards studies favouring drug over placebo, perhaps tending to inflate
available efficacy estimates.
Based on sensitivity or influence analysis, excluding one trial at a time and recalculating pooled rate ratio estimates, we found only trivial effects on the pooled rate ratio, including omission of the shortest trial,31 which accordingly was included in the overall analyses. The US federal grant-supported Treatment for Adolescents with Depression study by March et al5 was identified as the most influential study, based on its unusually large effect size (RR=1.74, 95% CI 1.29–2.34) and larger sample size (n=221) than in any other trial (Table DS3). Excluding this single trial reduced the overall pooled rate ratio to 1.20 (95% CI 1.12–1.28) from the overall rate ratio of 1.22.
Meta-regression analyses
Characteristics associated with a change in estimates of treatment effect
(rate ratio) of at least 0.10 included outcome based on protocol completion
v. LOCF methods; greater illness severity at entry; and published
v. unpublished reports. Rate ratio estimates increased by
approximately 10% (95% CI –13.4 to 31.8) for each 20% increase in
depression severity ratings at intake. The less common method of
completer analysis (only 6 of 29 trials) was associated with a
nearly 20% (95% CI –11.6 to 51.3) greater rate ratio than LOCF-based
methods. Other factors considered (drug type, sample size, publication year,
funding source, exposure weeks, estimated study methodological quality
ratings, age group, average drug dose and in-patient or out-patient status)
had only weak associations with drug/placebo response rate ratios. By
adjusting the computed pooled response rate ratios for all three most
influential covariates, the rate ratio difference between older
and newer antidepressants persisted, but was even smaller (0.19)
than without such adjustment (0.22). Specifically, these considerations fail
to support the possibility that SRIs may be superior in efficacy to tricyclic
antidepressants.
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In line with recent British advisory recommendations,56 this systematic review found limited efficacy for all types of antidepressants in short-term randomised controlled trials in juvenile depression. Earlier reviews of treatment of juvenile depression concluded that tricyclic antidepressants were ineffective, particularly in prepubertal children, with marginal efficacy in adolescents.57–59 Reviews of SRIs also have suggested limited antidepressant benefits in cases of juvenile depression.12,59–65 Seemingly consistent with selective UK and US regulatory approval of fluoxetine for juvenile depression, there is some evidence of its apparent superiority to other SRIs, although this impression rests heavily on one large study with an unusually large drug–placebo separation.5 Conceivably the unusually long duration of action of fluoxetine46 might be advantageous among treatment-reluctant and poorly treatment-adherent young patients. That antidepressants, and particularly SRIs, have mood-elevating effects in children and young adolescents is suggested by the substantial risk of these patients becoming excited or manic during treatment for apparent major depression.66 Moreover, the modest evidence of efficacy in randomised controlled trials is at variance with the widespread empirical acceptance of modern antidepressants in paediatric clinical practice.67–69
A striking finding in our analysis is the limited difference found between outcomes with SRIs v. tricyclic antidepressants: with raw median response rates actually tended to favour the latter drugs, and meta-analytically pooled rate ratios differed little (7.7%), with highly overlapping confidence intervals, indicating statistical non-difference (Table DS2). Superiority of antidepressants over placebo in juvenile patients with major depressive disorder, based on statistical significance, was found in only 20% of 30 comparisons, including 0/14 comparisons involving tricyclic antidepressants, 0/4 involving other antidepressants, and only 5/12 comparisons involving SRIs (Table DS1). However, this way of comparing study results is confounded by the severe mismatching of participant numbers and treatment duration in trials of tricyclic antidepressants v. SRIs: notably, trials of SRIs had over six times greater treatment exposure in person-weeks (Table DS2). Greater statistical power gained with higher participant counts can yield significant separation of drug from placebo, even though such separation may be small and of questionable clinical significance. Recent trials have been much larger (and longer) and so more likely to yield statistical separation of SRIs v. placebo, but without either a clinically or statistically meaningfully larger pooled effect size (rate ratio or rate difference) or smaller NNT in association with larger participant counts, as noted above. This mismatching of statistical power and exposure time (favouring SRIs) is to be contrasted with a 34% lower estimated equivalent daily dosing with SRIs than tricyclic antidepressants (Table DS2), which had a negligible effect on meta-regression outcomes. Nevertheless, in depressed patients of any age at high risk of suicidality, routine use of tricyclic antidepressants cannot be recommended in view of their known cardiotoxic effects and associated mortality in overdose.
Proposed explanations for such disappointing findings in the experimental therapeutics of juvenile depression include both methodological aspects of trial design and clinical aspects of juvenile mood disorders. Possibilities include relatively high rates of response to placebo or other non-specific interventions; age-inappropriate or insufficiently sensitive outcome measures; inadequately powered trials; adverse case selection (e.g. minimally ill, uncertain or heterogeneous diagnoses, previous treatment failures, poorly cooperative participants); incomplete control of substance misuse; inadequate dosing or duration of treatment; and simple lack of efficacy in juvenile v. adult mood disorders.60,63,70–73 The average 60% drug response rate in juvenile depressed patients (Tables DS1, DS2) was similar to that reported in depressed adults,46,53,55 suggesting that neither the major developmental changes in drug disposition74,75 nor possible changes in pharmacodynamics are involved in the limited superiority of antidepressants to placebo in juvenile depression.
Poor separation in responses to antidepressants v. placebo may reflect recruitment of juveniles with relatively heterogeneous illnesses, who may meet nominal diagnostic criteria for major depressive disorder, but whose symptoms may not be representative of classic disorders, such as the clearly endogenous and melancholic features associated with adult major depression. Juvenile major depressive disorder was not accepted into the official American diagnostic nomenclature until the late 1990s.17,76,77 Differentiation of mood disorders from other prevalent behavioural and emotional conditions in young patients remains descriptive. Improved diagnostic and clinical rating methods may increase reliability of the diagnosis of major depressive disorder in children and adolescents, although not necessarily assure valid comparison with major depressive syndromes of adults.70,71,78 Even though median baseline depression severity scores were at the mid-range of scale scores (averaging 50%; Table DS2), suggesting substantial illness severity, sampling of young patients with depression may include a high proportion of relatively mildly ill patients, who have most probably never received in-patient treatment, and who are more likely to improve spontaneously with or without additional effects of placebo treatment.79
Importantly, prepubertal children with depression may differ biologically from adolescents or adults,66,74,80 and it remains unclear whether depression in prepubertal children is a substantially different disorder from that found in adolescents or adults, perhaps including developmental differences in either the pharmacodynamics of antidepressants or in their clinical effects.66,81 The current data preclude adequate assessment of potential developmental effects owing to the paucity of studies of children considered separately. Only 4 of 30 treatment comparisons and 4% of participants involved children only; all were treated with tricyclic antidepressants, none with modern drugs. Nevertheless, within the limits imposed by the few studies of children, no major systematic difference was apparent between depressed children and adolescents in average rates of clinical improvement during treatment with either antidepressants or placebo, nor in pooled rate ratios (Table 1).
Implications
The limited benefits of antidepressant treatment for depression in children
and adolescents found in reported results of randomised controlled trials have
important risk–benefit implications, given current discussion of risks
that may include more suicidal thinking and perhaps self-injurious behaviour
in juvenile patients with depressive or anxiety disorders during treatment
with an SRI. Clearly, additional research is required to clarify the basis of
the limited juvenile responses to antidepressant treatments considered
standard in adult major depression, to specify developmental changes in
antidepressant potency and pharmacodynamics as well as potential age-related
differences in treatment responses and risks involved. Moreover, questions of
risks v. benefits of antidepressant treatment of juvenile depression
require critical assessments of the relative value of modest effect sizes,
typically based on 50% reductions in symptom ratings as reviewed here,
v. actual clinical effectiveness (efficacy plus acceptability
sufficient to yield clinical recovery), which remains to be studied in
children and adolescents. Outcomes in future trials might be enhanced by
including larger samples, more severely depressed participants, more children
and narrower age groups. Trials should also include information on the
proportion of individuals with mild or moderate depression at baseline.
Moreover, results of all well-designed trials should be made publicly
available regardless of outcome, since publication bias may affect available
meta-analytical estimates of efficacy or adverse effects on which clinical
therapeutic practices and public health policies are based. Urgent goals
should include development of more effective, safe, cost-effective and
accessible short-term and long-term treatments for juvenile depression, with
specific consideration of differences between prepubertal children and
adolescents.
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