Are selective serotonin re-uptake inhibitors associated with an increased risk of self-harm by antidepressant overdose?
OBJECTIVE
To investigate likelihood of self-harm by overdose with antidepressant drugs of different types by examining hospital admission data and poisons inquiries and relating them to prescribing.


METHODS
Retrospective analysis of prospectively collected data on overdose admissions, poisons inquiries and prescribing of antidepressants in Edinburgh and Scotland.


METHODS
Poisons treatment unit of the Royal Infirmary of Edinburgh and its surrounding catchment for overdose cases and Scotland for poisons inquiries.


METHODS
All patients admitted to the Royal Infirmary of Edinburgh between 1 January 2000 and 31 December 2002 with an overdose involving an antidepressant.


METHODS
Overdose admissions (patients) in relation to prescribing in Edinburgh and poisons inquiries in relation to prescription rates in Scotland.


RESULTS
There were 1656 admissions involving 1343 patients. The likelihood of admission for an individual patient in relation to volume of prescribing (likelihood ratio: 95%CI) in the catchment was somewhat smaller for amitriptyline (0.83:0.74-0.92) and sertraline (0.79:0.63-0.99), and somewhat greater for mirtazapine (1.99:1.57-2.51), trazadone (1.30:1.09-1.54) and venlafaxine (0.97:1.81-1.16) [corrected] For poisons inquiries in Scotland, the excess for venlafaxine and mirtazapine was confirmed and likelihood of an inquiry lowest for selective serotonin re-uptake inhibitors (SSRIs).


CONCLUSIONS
There was no evidence of an excess likelihood of presentation with overdose with SSRIs, and the likelihood was reduced with sertraline. There was a small excess of both admissions and poisons inquiries for mirtazapine and venlafaxine. This is a concern in view of the increased toxicity of venlafaxine in overdose in comparison with SSRIs.
Bateman
D N
DN
Scottish Poisons Information Bureau (NPIS Edinburgh), Royal Infirmary of Edinburgh, 51 Little France Crescent, EH10 4SA Edinburgh, Scotland. spib@luht.scot.nhs.uk
Chick
J
J
Good
A M
AM
Kelly
C A
CA
Masterton
G
G
D000328:Adult; D000639:Amitriptyline / Q000008:administration & dosage / Q000627:therapeutic use; D000929:Antidepressive Agents, Tricyclic / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D015283:Citalopram / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D003511:Cyclohexanols / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D004316:Doxepin / Q000008:administration & dosage / Q000627:therapeutic use; D062787:Drug Overdose; D011307:Drug Prescriptions / Q000706:statistics & numerical data; D004636:Emergency Service, Hospital; D005260:Female; D005473:Fluoxetine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D006801:Humans; D007099:Imipramine / Q000008:administration & dosage / Q000627:therapeutic use; D007255:Information Services / Q000706:statistics & numerical data; D008297:Male; D008803:Mianserin / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000078785:Mirtazapine; D017374:Paroxetine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D010343:Patient Admission / Q000706:statistics & numerical data; D010359:Patient Readmission / Q000706:statistics & numerical data; D011039:Poison Control Centers / Q000706:statistics & numerical data; D012189:Retrospective Studies; D018570:Risk Assessment; D012606:Scotland; D016728:Self-Injurious Behavior / Q000139:chemically induced*; D017367:Selective Serotonin Reuptake Inhibitors / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D020280:Sertraline / Q000008:administration & dosage / Q000627:therapeutic use; D014196:Trazodone / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D000069470:Venlafaxine Hydrochloride
D000639:Amitriptyline; D000929:Antidepressive Agents, Tricyclic; D015283:Citalopram; D003511:Cyclohexanols; D004316:Doxepin; D005473:Fluoxetine; D007099:Imipramine; D008803:Mianserin; D000078785:Mirtazapine; D017374:Paroxetine; D017367:Selective Serotonin Reuptake Inhibitors; D020280:Sertraline; D014196:Trazodone; D000069470:Venlafaxine Hydrochloride