Suicide and self-harm following prescription of SSRIs and other antidepressants: confounding by indication

Rebecca C. Didham, Doug W. McConnell, Hayden J. Blair, David M. Reith

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Abstract

Aim: To identify the incidence and risk of suicide and self harm, among patients prescribed antidepressant drugs.

Methods: A retrospective cohort study, with nested case control, of patients identified from a nonrandom sample of general practices in New Zealand from 1996 to 2001. A total of 57 361 patients who received a prescription for a single antidepressant were identified from the RNZCGP Research Unit Database. Suicides within 120 days of a prescription were identified from the New Zealand National Mortality Database and self-harm events within 120 days of a prescription were identified from the New Zealand Hospital discharge database.

Results:
26 suicides and 330 episodes of self-harm were identified within 120 days of an antidepressant prescription. On univariate analysis the association, expressed as OR (95% CI), between selective serotonin reuptake inhibitors (SSRIs) and self harm and suicide were 2.26 (1.27–4.76) and 1.92 (0.77–4.83), respectively. When corrected for the confounding effects of age, gender and depression/suicidal ideation there was an association between SSRIs and self harm, OR 1.66 (95% CI 1.23–2.23), but not for suicide, 1.28 (0.38–4.35). Paroxetine was a significant risk factor for suicide on univariate analysis, 4.23 (1.19–14.95), but not when corrected for age, gender and depression/suicidal ideation, 2.76 (0.30–24.87).

Conclusions: Age, gender and pre-existing depression/suicidal ideation are important confounders in observational studies of the association between antidepressants and suicide or self harm.
Original languageEnglish
Pages (from-to)519-525
Number of pages7
JournalBritish Journal of Clinical Pharmacology
Volume60
Issue number5
DOIs
Publication statusPublished - Nov 2005
Externally publishedYes

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