BMJ  2005;330:1149-1150 (14 May), doi:10.1136/bmj.330.7500.1149-b

Letter

Do selective serotonin reuptake inhibitors cause suicide?

Data seem to be incorrect

EDITOR—Fergusson et al report that the risk of suicide attempts is significantly greater for patients enrolled in short term randomised controlled trials of selective serotonin reuptake inhibitors (SSRIs) than with placebo (odds ratio 2.28, P < 0.02) and other interventions (not including tricyclics) (odds ratio 1.94).¹ They are also one of the few groups to report that completed suicides (fatal attempts) were also higher with SSRIs than tricyclics (odds ratio 7.27 [corrected to 1.08 (0.28 to 4.09), see correction, 19 March, p 653]). This seems to have led Cipriani et al to say that there is almost a double risk of fatal and non-fatal risk of suicide for people taking SSRIs.²

An increased risk of fatal overdoses when using SSRIs is hard to understand, particularly when the comparison is tricyclics, given their acknowledged toxicity in overdose.^3-5 I therefore rechecked the odds ratios from the data given by Fergusson et al and found most of them to be incorrect.

For example, they say that the odds ratio of suicide attempts in SSRIs compared with others is 1.94; but with 27 SSRI cases out of 4130 treated patients and 18 control cases out of 4233 treated patients the odds ratio is 1.54 (95% confidence interval 0.85 to 2.8)—that is, non-significant. Changing the denominator to 8856 and 9059 (all trials) makes no difference to the result.

Similarly, Fergusson et al say that the odds ratio for non-fatal attempts was 2.25 whereas I calculate it at 1.89 (0.96 to 3.73), again non-significant. Perhaps most incomprehensibly regarding the odds of completed suicide and tricyclics, the number of SSRI cases is five and that of tricyclic antidepressant cases is four—a non-significant difference.

In conclusion, either most of the raw data printed in table 1 are wrong or one of us has miscalculated dramatically.

Leicester General Hospital, Leicester LE5 4PW alex.mitchell{at}leicspart.nhs.uk

---

Competing interests: None declared.

References

1. Fergusson D, Doucette S, Cranley Glass K, Shapiro S, Healy D, Hebert P, et al. Association between suicide attempts and selective serotonin reuptake inhibitors: systematic review of randomised controlled trials. BMJ 2005;330: 396. (19 February.)[Abstract/Free Full Text]
2. Cipriani A, Barbui C, Geddes JR. Suicide, depression, and antidepressants. BMJ 2005;330: 373-4. (19 February.)[Free Full Text]
3. Cheeta S, Schifano F, Oyefeso A, Webb L, Ghodse AH. Antidepressant-related deaths and antidepressant prescriptions in England and Wales, 1998-2000. Br J Psychiatry 2004;184: 41-7.[Abstract/Free Full Text]
4. Henry JA, Alexander CA, Sener EK. Relative mortality from overdose of antidepressants. BMJ 1995;310: 221-4.[Abstract/Free Full Text]
5. Shah R, Uren Z, Baker A, Majeed A. Deaths from antidepressants in England and Wales 1993-1997: analysis of a new national database. Psychol Med 2001:31: 1203-121.[CrossRef][ISI][Medline]

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

Relevant Articles

Association between suicide attempts and selective serotonin reuptake inhibitors: systematic review of randomised controlled trials
BMJ 2005 330: 653. [Full Text] [PDF]

Suicide, depression, and antidepressants

Andrea Cipriani, Corrado Barbui, and John R Geddes
BMJ 2005 330: 373-374. [Extract] [Full Text] [PDF]

Association between suicide attempts and selective serotonin reuptake inhibitors: systematic review of randomised controlled trials

Dean Fergusson, Steve Doucette, Kathleen Cranley Glass, Stan Shapiro, David Healy, Paul Hebert, and Brian Hutton
BMJ 2005 330: 396. [Abstract] [Full Text] [PDF]

Relative mortality from overdose of antidepressants

John A Henry, Carol A Alexander, and Ersin K Sener
BMJ 1995 310: 221-224. [Abstract] [Full Text]