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

Br J Clin Pharmacol. 2005 Nov;60(5):519-25. doi: 10.1111/j.1365-2125.2005.02480.x.

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.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antidepressive Agents / adverse effects*
  • Epidemiologic Methods
  • Female
  • Humans
  • Male
  • Middle Aged
  • New Zealand / epidemiology
  • Self-Injurious Behavior / chemically induced*
  • Self-Injurious Behavior / epidemiology
  • Serotonin Uptake Inhibitors / adverse effects*
  • Suicide / statistics & numerical data*

Substances

  • Antidepressive Agents
  • Serotonin Uptake Inhibitors