Keith Hawton1, Anne Ferrey2, Deborah Casey2, Claudia Wells3, Alice Fuller4, Clare Bankhead4, Caroline Clements5, Jennifer Ness6, David Gunnell7, Navneet Kapur8, Galit Geulayov2. 1. Department of Psychiatry, University of Oxford, UK; Oxford Health NHS Foundation Trust, Oxford, UK. Electronic address: keith.hawton@psych.ox.ac.uk. 2. Department of Psychiatry, University of Oxford, UK. 3. Office for National Statistics, UK. 4. Nuffield Department of Primary Care Health Sciences, University of Oxford, UK. 5. Manchester Academic Health Sciences Centre, University of Manchester, UK. 6. Centre for Self-harm and Suicide Prevention Research, Derbyshire Healthcare NHS Foundation Trust, UK. 7. School of Social and Community Medicine, University of Bristol, UK. 8. Manchester Academic Health Sciences Centre, University of Manchester, UK; Greater Manchester Mental Health NHS Foundation Trust, UK.
Abstract
BACKGROUND: Analgesics are used most frequently in fatal and non-fatal medicinal self-poisonings. Knowledge about their relative toxicity in overdose is important for clinicians and regulatory agencies. METHODS: Using data for 2005-2012 we investigated case fatality (number of suicides relative to number of non-fatal self-poisonings) of paracetamol, aspirin, codeine, dihydrocodeine, tramadol, paracetamol with codeine (co-codamol), paracetamol with dihydrocodeine (co-dydramol), ibuprofen and co-proxamol (paracetamol plus dextropropoxyphene; withdrawn in the UK in 2008 due to high toxicity). Data on suicides obtained from the Office for National Statistics and on non-fatal self-poisonings from the Multicentre Study of Self-harm in England. Case fatality was estimated for each drug, using paracetamol as the reference category. RESULTS: Compared to paracetamol and based on single drug deaths the case fatality index of dihydrocodeine was considerably elevated (odds ratio (OR) 12.81, 95% Confidence Interval (CI) 10.19-16.12). Case fatality indices for tramadol (OR 4.05, 95% CI 3.38-4.85) and codeine (OR 2.21, 95% CI 1.81-2.70) were also significantly higher than for paracetamol. The results when multiple drug deaths were included produced similar results. The relative toxicity of co-proxamol far exceeded that of the other analgesics. LIMITATIONS: Data on fatal self-poisonings were based on national data, whereas those for non-fatal poisonings were based on local data. CONCLUSIONS: Dihydrocodeine and tramadol are particularly toxic in overdose and codeine is also relatively toxic. They should be prescribed with caution, particularly to individuals at risk of self-harm.
BACKGROUND: Analgesics are used most frequently in fatal and non-fatal medicinal self-poisonings. Knowledge about their relative toxicity in overdose is important for clinicians and regulatory agencies. METHODS: Using data for 2005-2012 we investigated case fatality (number of suicides relative to number of non-fatal self-poisonings) of paracetamol, aspirin, codeine, dihydrocodeine, tramadol, paracetamol with codeine (co-codamol), paracetamol with dihydrocodeine (co-dydramol), ibuprofen and co-proxamol (paracetamol plus dextropropoxyphene; withdrawn in the UK in 2008 due to high toxicity). Data on suicides obtained from the Office for National Statistics and on non-fatal self-poisonings from the Multicentre Study of Self-harm in England. Case fatality was estimated for each drug, using paracetamol as the reference category. RESULTS: Compared to paracetamol and based on single drug deaths the case fatality index of dihydrocodeine was considerably elevated (odds ratio (OR) 12.81, 95% Confidence Interval (CI) 10.19-16.12). Case fatality indices for tramadol (OR 4.05, 95% CI 3.38-4.85) and codeine (OR 2.21, 95% CI 1.81-2.70) were also significantly higher than for paracetamol. The results when multiple drug deaths were included produced similar results. The relative toxicity of co-proxamol far exceeded that of the other analgesics. LIMITATIONS: Data on fatal self-poisonings were based on national data, whereas those for non-fatal poisonings were based on local data. CONCLUSIONS: Dihydrocodeine and tramadol are particularly toxic in overdose and codeine is also relatively toxic. They should be prescribed with caution, particularly to individuals at risk of self-harm.