Transcript CHOOSE YOUR POISON: CORRELATIONS BETWEEN

An Analysis of Age
and Gender Influences on
the Relative Risk for Suicide
& Psychotropic Drug SelfPoisoning
AH Dawson1, NA Buckley2, IM Whyte1,
P Hazell3, A Meza4, H Britt4
(1) Depart. of Clinical Toxicology, Newcastle Mater Hospital NSW, (2) Discipline of Clinical Pharmacology, Univ of Newcastle
(3) Discipline of Psychiatry, Univ of Newcastle , (4) Family Medicne research Unit, Univ of Sydney
Background
 Psychiatric illness is a significant risk factor for
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both attempted and completed suicide
Psychotropic medications account for 80% of all
drug overdoses involving prescription
medications
Age and gender have been suggested to be
predictive of successful suicide (esp elderly
males)
Information about the relative risk of overdose
in subgroups of the population may assist in
the decision to treat and in the choice of an
appropriate psychotropic agent
Can the benefit of treatment be balanced
against the risk of drug overdose
Aims
 To compare the age and gender distribution of
patients prescribed psychotropic drugs with
patients attempting and completing suicide
with these drugs
Hypothesis
 If the relative risk of self-poisoning per
prescription is the same across the population,
then the rate of self-poisoning in different age
and gender groupings should reflect the
prevalence of prescription of these drugs
Data Sources
Demographic: Australian 1991
census: Hunter data
Toxicology: Newcastle
Study Data Subset
Clinical Toxicology self-poisoning
database.
Psychotropic drugs (antipsychotic,
antidepressant, sedative and
anxiolytic drugs)
Newcastle forensic database
Adults (age >14)
Prescription: Australian
Morbidity and Treatment Survey
1990-1991 (AMTS) Encounter based
survey involving a random sample of 495
general practitioners who recorded details
regarding over 100,000 doctor/patient
encounters
Newcastle area (postcodes 22802310)
Results
 The odds ratio (ORs) for self-poisoning were
higher for < 45 years & yet this group was least
likely to be prescribed psychotropic drugs
 Males had a much higher rate of completed
suicide using more lethal methods
 The ORs for self-poisoning and suicide with
psychotropic drugs, after correction for
prescription rates
 aged 15 to 24 were 11.1 and 1.7 respectively
 aged 25 to 44 had ORs of 4.9 and 4.3
 aged 75+ had ORs of 0.03 and 0
 Females were slightly more likely to poison
themselves with psychotropic drugs (OR 1.2),
however the situation reversed after correction for
prescription rates (OR 0.69)
Conclusions
 Greater caution should be exercised in
prescribing for those under 45, given their
relatively higher risk of drug overdose, and the
least toxic compounds should be used
 The risk (of self-poisoning) in the elderly may
have been overstated, so that some patients may
have been denied the benefit of adequate
treatment
Discussion
 Some prescriber groups including psychiatrists
were not included in the sampling group of
doctors for the AMTS database. However:
 Over 80% of antidepressant and antipsychotic prescriptions
and 95% of sedative/hypnotic drug prescriptions are written
by general practitioners (HIC data)
 There were no differences between these drug classes and
even if an additional 5% of sedative/hypnotic prescriptions
were all written for the under 45 aged group this would not
account for the observed difference
 The self poisonings only include those who
presented to hospital or reported to the coroner
 It is plausible that a number of suicides might be certified as
death from other causes. However the proportion of suicides
due to poisoning was about a fifth across all age groups with
the major difference being the type of poisons used, thus
under the reporting of suicide by poisoning is unlikely to
explain the observed differences