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An Analysis of Age and Gender Influences on the Relative Risk for Suicide & Psychotropic Drug Self-Poisoning. AH Dawson 1 , NA Buckley 2 , IM Whyte 1 , P Hazell 3 , A Meza 4 , H Britt 4
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An Analysis of Age and Gender Influences on the Relative Risk for Suicide & Psychotropic Drug Self-Poisoning 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 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
Demographic: Australian 1991 census: Hunter data Study Data Subset Psychotropic drugs (antipsychotic, antidepressant, sedative and anxiolytic drugs) Adults (age >14) Newcastle area (postcodes 2280-2310) Toxicology: Newcastle Clinical Toxicology self-poisoning database. Newcastle forensic database 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 Data Sources
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