Ketamine, a drug mainly used as an anaesthetic, could double up as an effective treatment for long-term pain following surgery - with the potential of saving billions in healthcare costs.
A review of studies, led by Dr Philip Peyton from the Austin Hospital and University of Melbourne, presented at the Euroanaesthesia 2016 conference in London, found that ketamine was the safest and most effective option available.
"Ketamine has powerful analgesic properties useful in management of severe acute pain,” Dr Peyton, an expert in anaesthesiology, tells SBS.
Chronic or persistent post-surgical pain (PPSP) is characterised as pain that lasts longer than three to six months after surgery and is a relatively new phenomenon that medical experts are still attempting to understand.
According to the researchers, an estimated one in eight patients report PPSP after a major operation, and a third of them rate their pain as severe, however a 2015 study suggests that anywhere between 5 to 85 per cent of patients experience PPSP.
“Peristent or chronic post-surgical pain is now recognised as one of the most common and debilitating complications of major surgery,” says Dr Peyton.
"Treatment of established chronic pain is difficult and hard to access, so finding preventive strategies is important.”
He adds, "Should further studies confirm our findings on ketamine, healthcare systems will have a cheap and effective means to treat this condition, allowing huge cost savings."
The research involved both a randomised trial conducted by Peyton and his colleagues, where 80 patients were treated with either a placebo or ketamine, and a meta-analysis of eight major studies with a combined 563 participants.
They found that patients who were treated with ketamine were half as likely to experience PPSP compared with patients who had been given the placebo.
"[Ketamine] is a potent inhibitor of the NMDA receptor, which we know is involved intimately in the neural processes that lead to development of chronic pain after injury,” says Dr Peyton.
“Many other drugs acting on different pathways have been investigated as well, but published studies in the field are small and generally underpowered – meta-analysis is our best tool for examining and assessing this varied data.”
Professor Guy Ludbrook, from the University of Adelaide’s Pain and Anaesthesia Research Clinic, was impressed by the research and the promise shown by ketamine.
“[PPSP] is a condition that until a few years ago was very, very poorly recognised, it’s only in recent years that we’ve come to understand that patients may have persisting pain and it can be quite severe,” Prof Ludbrook tells SBS.
“A number of drugs have been trialled and some of these drugs are effective for other forms of persistent pain, such as Lyrica or lidocaine… but by and large, the evidence hasn’t been as impressive as we might have liked for those.”
Chronic pain in general affected an estimated one in five Australians in 2007, costing the economy $34 billion, according to the ABS.
However, Prof Ludbrook was critical of prioritising the cost of drug therapies over their potential benefits that could reduce direct and indirect costs on patients’ lives.
“While cost is relevant, we always have to judge the cost of the drugs against the benefit – if a drug has significant cost and an enormous benefit, we would not be afraid to use such a drug,” he said.
The researchers advised that further study, such as a large multi-centre randomised trial, would be needed to assess the optimal dosage of ketamine in treating PPSP and whether it should form part of a multimodal treatment regime.
"A large clinical trial, requiring several thousand patients, is needed to provide a definitive answer as to whether ketamine is effective in reducing the risk of chronic pain after surgery,” says Dr Peyton.