Safe use of SSRIs in young adults: How strong is evidence for new suicide warning?

[David Baxter PhD]

Safe use of SSRIs in young adults: How strong is evidence for new suicide warning?
by Michael F. Grunebaum, MD, and J. John Mann, MD
Current Psychiatry, Vol. 6, No. 11 / November 2007

Pediatric suicide rates increased in 2003-04 after the black-box warning, which has now been extended to patients age 18 to 24.

Clinical Point
In 2003 to 2004, after the ‘black-box’ warning, pediatric antidepressant prescriptions declined and suicide rates increased 11%

Mr. B, age 20, has taken a semester leave from college because of gradually worsening depressed mood. Over the past 2 months he has lost interest in jogging and playing piano—which he usually enjoys. He reports reduced libido, middle insomnia, loss of appetite, feeling as if his head is “full of cotton,” trouble concentrating, and waking in the morning with a sense of dread. His anxiety dissipates during the day, but he continues to feel sad and sometimes weepy, which is unusual for him.

Mr. B reports feeling hopeless at times and has had vague thoughts about life being “not worth it if I continue to feel like this” but denies specific suicide plans. Your initial impression is that Mr. B is in the midst of a major depressive episode and that a selective serotonin reuptake inhibitor (SSRI) is indicated. As you finish taking his history, you run through your mind the pros and cons of the recommendation you will make to him.

Do SSRIs raise or lower the risk for suicidal behavior in young adults such as Mr. B? The answer is complicated and goes beyond an “either/or” question, as the FDA acknowledged in May 2007 when it:

• extended the black-box warning of increased suicidality risk with antidepressants to cover adults age 18 to 24 as well as children and adolescents
• included language in the warning about the benefits of treating depression and the suicide risk associated with untreated depression, given concerns about declining antidepressant prescriptions and rising suicides among youth.¹

To help you make informed decisions when treating depression in adults, this article reviews the studies leading up to and following the FDA’s meta-analysis of antidepressant trial data in patients age 18 and older. Our goal is to provide a framework for clinical treatment of adults age 18 to 24 and those age ≥25.

FDA’s pediatric suicidality analysis: What the data showed
The FDA meta-analysis designed to investigate a reported association between antidepressants and suicidality in children and adolescents found contradictory results:

• Pooled adverse event data from 24 pediatric antidepressant trials totaling >4,400 patients showed a higher risk of suicidal ideation or behavior (no suicides occurred) with antidepressants (4%) vs placebo (2%).
• Systematically collected suicide-related item scores from 17 of the trials showed no evidence that antidepressants worsen suicidality or cause it to emerge.

One interpretation of these findings is that antidepressants’ effect on suicidality is small and therefore subject to measurement error.

Another is ascertainment bias; any side effect associated with active medication encourages discussion with the clinician and may distort the frequency of reported adverse events.

The FDA meta-analysis also found:

• Relative risk for suicidality ranged 10-fold among agents, from 0.9 with fluoxetine to 8.8 with venlafaxine.
• Most suicide-related events occurred in subjects having the highest baseline levels of suicidality.
• Hostility and agitation emerged with SSRI use, particularly during the first month of treatment.
• Patient age, sex, or history of suicide attempt/ideation did not affect the results.

Source: Reference⁷

First hints of suicidality
SSRIs revolutionized depression treatment. From 1985 to 1999, annual U.S. antidepressant prescriptions quadrupled, with SSRIs accounting for 70% of the increase (see “Antidepressants and suicide risk, 1985 to 2007”). At the same time, the age-adjusted suicide rate:

• dropped 22.5% for women (who account for twice as many antidepressant prescriptions as men)
• dropped 12.8% for men (without change in the rank order of suicide methods).²

For many patients, increased antidepressant use improved treatment of major depressive and other antidepressant-responsive disorders. In 1990, however, case reports suggested SSRIs might cause suicidal thoughts or behavior.³ Hypothesized mechanisms included increased aggression⁴ and akathisia.⁵ An FDA review found no proof, and a meta-analysis of data from 17 double-blind, randomized, controlled trials found no association between fluoxetine and suicidal thoughts or behavior.⁶

The debate rekindled in June 2003 when the British Committee on Safety of Medicines warned against using paroxetine or venlafaxine in children. After conducting its own meta-analysis, the FDA in 2004 ordered a black-box warning about suicidality and the use of antidepressants in children and adolescents.⁷

After the pediatric ‘black box.’ Antidepressant prescriptions for children and adolescents declined in the years 2003 to 2004, as did diagnosis of pediatric depression.^8-10 Antidepressant prescribing also showed signs of shifting from general practitioners to psychiatrists.⁸ At the same time, the suicide rate among youth age <17 rose 11% from 1.26/100,000 to 1.4/100,000—after 3 consecutive years of decline—according to new data from the Centers for Disease Control and Prevention.¹¹ In patients age > 60, SSRI prescriptions continued to rise and suicide rates fell,⁹ a pattern of change consistent with antidepressants protecting against suicide.

An independent meta-analysis by Bridge et al¹² examined the pediatric trial data used in the FDA meta-analysis plus 7 additional studies. Its findings differ in 2 important ways from those of the FDA review:

• Antidepressants—including others besides fluoxetine—showed efficacy in treating anxiety disorders and depression in children and adolescents.
• The frequency of suicide-related adverse events (no trial patients committed suicide) was approximately 3% on active medication—25% lower than the FDA estimated rate—and 2% on placebo, similar to the FDA estimate.

The number needed to treat (NNT)— number of patients who must be treated to get a therapeutic response that would not have happened with placebo—ranged from 3 to 10. The number needed to harm (NNH)—number of patients who must be treated for 1 suicidal ideation/nonfatal attempt to occur that would not have happened with placebo—ranged from 112 to 200. The authors interpreted this as “indicating a favorable overall risk-to-benefit profile for antidepressants in the treatment of pediatric [major depressive disorder], [obsessive-compulsive disorder] (OCD), and non-OCD anxiety disorders.”¹² These findings appear to support the efficacy of antidepressants in pediatric patients and a favorable risk-benefit ratio.

What about adults?
Overall effect. A subsequent FDA meta-analysis of antidepressant clinical trial data in adults¹³ found 8 suicides in 372 trials totaling nearly 100,000 persons. All occurred in the 295 trials with psychiatric indications. Among these psychiatric trials, 59% had a suicidal behavior/ideation event in either the test-drug or placebo arm, and 41% had none. Eleven antidepressants were included in the meta-analysis:

• 6 SSRIs (citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline)
• 2 SNRIs (duloxetine and venlafaxine)
• 3 others (bupropion, mirtazapine, and nefazodone).

Overall, antidepressants showed a protective (antisuicidal) effect in adults as compared with placebo (odds ratio 0.85 [95% CI: 0.71 to 1.02, P=0.08]), with no difference in effect between SSRIs and non-SSRIs.

Age-specific findings. When the FDA analysis was stratified by age, however, antidepressants’ benefit appeared greater for patients age ≥25 than for those age 18 to 24. The data suggested:

• elevated suicidality risk among adults age <25
• neutral or possibly protective effect for adults age 25 to 64
• protective effect in adults age ≥65 (Table 1).¹³

For 18-to 24-year-olds, the suicide rate was 0.03% (~1/4,000) in these mostly 8- to 12-week trials, and the suicide attempt rate was 0.55% (~1/200). For comparison, the lifetime prevalence of suicide was 2.2% to 8.6%—depending partly on illness severity—in a meta-analysis of patients with mood disorders.¹⁴

The odds ratio for suicidal behavior (preparatory acts, attempt, or suicide) for subacts, attempt, or suicide) for subjects age 18 to 24 on test drug vs placebo was 2.31 (95% CI: 1.02, 5.64) [event rate/sample: 23/3810 vs 8/2604]. NNH was 333, which means 333 adults in this age group would need to be treated with an antidepressant for 1 to experience a suicidal behavior event that would not have happened with placebo.

Compare an NNH of 333 with the much lower NNH values associated with anti-arrhythmic treatment of atrial fibrillation (AF),¹⁵ an important cardiovascular cause of morbidity and mortality. A meta-analysis of 44 AF trials totalling 11,322 subjects found that—although “moderately effective” for maintaining sinus rhythm—all but 2 of the 10 drugs were pro-arrhythmic. Their NNH values of 17 to 119 are, at best, approximately one-third the NNH for antidepressants for suicidality in young adults based on adverse event reports. With NNH, higher is safer.

The age-related pattern the FDA found in its adult meta-analysis (Table 2)¹³ is consistent with its earlier pediatric analysis7 but not with the more recent findings of Bridge et al¹² that included a larger data set.

Mixed evidence
Aside from the FDA meta-analysis,¹³ what is the evidence that antidepressants—or specifically SSRIs—may cause suicidality in adults? Among 9 major published studies in adults of the relationship between SSRIs and suicidal behavior (deaths or attempts):

• 4 found no relationship (Table 3A)^16-19
• 2 found SSRIs may increase risk (Table 3B)^20-21
• 3 found SSRIs may reduce risk (Table 3C).^22-24

Evidence of protection
Epidemiologic studies. Suicide attempt rates in depressed youth and adults—including those age <25—are highest in the month preceding treatment and decline steadily after antidepressant treatment or psychotherapy begins, according to depression studies in a large group health plan. The pattern was the same whether a primary care physician or psychiatrist prescribed the antidepressant.²⁵

Evidence from psychological autopsies—which attempt to reconstruct a decedent’s thoughts, feelings, and actions before death—indicates that:

• Approximately 60% of suicides occur in persons with a mood disorder.²⁶
• Since the advent of SSRIs, the rate of postmortem detection of antidepressants in suicides has increased from 8% to 15%, whereas the rate of suicide deaths caused by antidepressant overdose remains at approximately 5%.²⁷

Similarly, in 1 suicide study, no antidepressants were detected postmortem in >50% of persons for whom they had been prescribed.²⁸ Systematic review finds substantial literature showing antidepressants’ efficacy for major depressive disorder.²⁹

Population studies in the United States³⁰ and many other^31,32—but not all³³—countries report a correlation between increased antidepressant prescriptions and lower suicide rates. Because of their limitations, however, population studies cannot make a causal connection between antidepressant prescribing and suicide rates.

Randomized, controlled trials (RCTs) reduce sources of bias, but designing an RCT to test whether or not antidepressants prevent suicide is not feasible. Given suicide’s relative infrequency (~11 per 100,000 persons/year in the United States¹¹), an RCT would require a sample of many thousands.

Meta-analyses of data pooled from smaller trials—such as the FDA studies of antidepressants and suicidality^7,13—are done to gain statistical power from larger samples, but these also have methodologic limitations (Table 4). Proxy outcomes— such as suicide attempts and ideation in high-risk samples—also can be studied, as we are doing in our clinic (see Related Resources).

CASE CONTINUED: Hypomanic, or just in love?
Mr. B reports no medical problems and is taking no medications. He talked to a college counselor 3 times during his freshman year when he was upset after a romantic breakup, found it helpful, and says his feelings resolved. He reports trying marijuana and cocaine “a few times.” During his sophomore year he felt very happy and energized about a new relationship for approximately 1 week, but says he was sleeping normally and functioning well in school during that time.

He describes his father as very “serious” and sometimes pessimistic, but he does not know if his father ever had mental health treatment. On mental status exam, Mr. B is neat, cooperative, and looks worried. His speech is slightly labored and ruminative. His psychomotor state is normal. He has no psychotic symptoms, and his cognitive exam is normal. Because he is out of school, he has no health insurance.

Clinical recommendations
Case presentations such as Mr. B’s raise questions you must consider when prescribing SSRIs, particularly to young adults:

• Was his “energized” episode a mild hypomanic period or just normal feelings of “being in love”?
• Is he minimizing substance use, which is a common comorbidity in depressed persons who die by suicide?
• He has melancholic symptoms; does he have psychotic ruminations he is not sharing?
• Without health insurance, how frequently will he be able to make follow-up appointments?

Prescribing any antidepressant for a specific patient is a complex, individualized decision based on weighing risks vs benefits. If you decide to prescribe an SSRI for Mr. B (who has never taken antidepressants), start with a low dose—such as fluoxetine, 10 mg/d, or sertraline, 25 mg/d—for several days. Because patients might not bring up suicidal thoughts or feelings, encourage openness and ask nonthreatening questions, such as, “Have you felt hopeless or had any thoughts that life isn’t worth it lately?” See Table 5³⁴ for other prescribing recommendations.

Suicide is the third leading cause of death in persons age 18 to 24¹¹ and a risk inherent in depression. Recent meta-analyses and large clinic population studies of adolescents and young adults suggest antidepressants—particularly SSRIs—show efficacy for depression and anxiety disorders¹² and reduce the risk of suicide attempts.²⁵

When deciding whether to prescribe an SSRI to an adult, weigh the small possible elevated risk in patients age 18 to 24 against the risk of untreated depression. The increase in suicide rates in children and adolescents after antidepressant prescription rates dropped in 2004 is consistent with a net beneficial effect of antidepressants. As in all collaborative treatment discussions, provide patients with comprehensive information on depression treatment options so that they can make informed decisions.

Note: See attached PDF file for Tables.

Related Resources

• MHRA Medicines and Healthcare products Regulatory Agency. Committee on Safety of Medicines. Expert Working Group on Selective Serotonin Reuptake Inhibitors. Interim report, 2003.
• Mann JJ. A current perspective of suicide and attempted suicide. Ann Intern Med 2002;136(4):302-11.
• Clinical Trial: Paroxetine Versus Bupropion for Treating People With High-Risk Major Depressive Disorder. Principal investigator: Michael F. Grunebaum, MD. National Institutes of Health.

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