“The controversial withdrawal of a common painkiller has dramatically cut suicides,” the BBC has reported. Co-proxamol, a powerful painkiller which was often given to arthritis patients, was gradually phased out between 2005 and 2007 after concerns that it was involved in a number of suicides and accidental poisonings. This gradual withdrawal reportedly led to 350 fewer suicides and accidental deaths in England and Wales during the withdrawal period. However, the charity Arthritis Care says that some patients now struggle to control their chronic pain.
A well-conducted study into the withdrawal of co-proxamol has provided good evidence that the drug’s withdrawal has reduced deaths from poisoning in England and Wales, and particularly suicides linked to co-proxamol overdose. This reduction was not accompanied by an increase in suicides using other drugs, although trends in other suicide methods were not tracked. When considered together with similar findings for Scotland, this suggests that the withdrawal has been effective. Other countries are also reported to be considering a withdrawal.
Where did the story come from?
The research was carried out by Professor Keith Hawton and colleagues from the Centre for Suicide Research at the University of Oxford Department of Psychiatry and other UK institutions. This work was funded by the National Institute for Health Research and published in the peer-reviewed British Medical Journal.
What kind of scientific study was this?
This was a time series study examining the withdrawal of co-proxamol, a painkiller which contains a combination of two active ingredients: paracetamol and dextropropoxyphene. There had long been concern that the painkiller was often involved in suicides and other fatal poisonings and, in January 2005, the UK Committee on the Safety of Medicines (CSM) advised that the licences for all products containing co-proxamol should be withdrawn. Following this advice, co-proxamol was withdrawn in December 2007.
According to the researchers, between 1997 and 1999, co-proxamol was the drug most frequently used for suicide in England and Wales. It was used in nearly a fifth of all suicides by drug-related poisoning.
The researchers assessed the impact of the CSM’s withdrawal of co-proxamol on deaths (suicides, open verdicts and accidental deaths) from drug poisoning in England and Wales using data from 1998 and 2007. They specifically looked at data on deaths involving only one type of analgesic (painkiller).
The researchers also explored how the prescription of other drugs changed over time. Prescribing data came from the Information Centre for Health and Social Care (England) and Health Solutions Wales, while mortality data came from the Office of National Statistics.
In a time series study such as this, the changing pattern of one factor is explored alongside the changes in another over time. Here researchers assessed the change in deaths from poisoning involving co-proxamol, other analgesics and all drugs, and prescribing patterns during this time. They were particularly interested in the effect of the withdrawal of co-proxamol on the prescribing of other analgesics and on their use in suicide.
What were the results of the study?
The study found that, as expected, following the warning on co-proxamol prescriptions of the drug fell sharply in the first two quarters of 2005 and continued to do so after this time. There was a similar decrease in the prescription of non-steroidal anti-inflammatory drugs and an increase in prescriptions of other painkillers (co-codamol, paracetamol, co-dydramol and codeine).
These changes were associated with a 62% reduction in all types of death involving co-proxamol. This equated to 349 fewer deaths in the withdrawal period between 2005 and 2007 than would be expected, based on quarterly death rates between 1998 and 2004. There was no evidence that other drugs were being used instead for suicides.
What interpretations did the researchers draw from these results?
The researchers concluded that the rationale for co-proxamol being withdrawn in the UK was its involvement in a large number of deaths from suicide. Their study showed that the withdrawal of co-proxamol was associated with 349 fewer deaths and 295 fewer suicides involving co-proxamol.
What does the NHS Knowledge Service make of this study?
This large time series study provides evidence that withdrawing co-proxamol products has led to an expected reduction in prescriptions of the drug, and is associated with a reduction in the number of deaths by suicide due to co-proxamol.
The study was limited to rates of death by poisoning and did not investigate trends in suicide by other methods. However, the evidence that there was no increase in suicides using other analgesics supports the success of the withdrawal initiative.
The withdrawal of co-proxamol has been controversial and BBC News quoted the head of policy and campaigns at Arthritis Care, who said that many people who used to be prescribed co-proxamol are now struggling to control their pain and have no effective alternative available to them.