Glucosamine: doubts cast over the benefits of treatment used by thousands

Island residents who have been taking the food supplement glucosamine on prescription to treat osteoarthritis pain in knee joints, may find themselves having to pay for it themselves in future, following claims it has no long-term beneficial effect.

A report, undertaken by a team of Canadian researchers, has seriously questioned the benefits of glucosamine. The findings will come as a shock to the hundreds of Islanders who regularly take it in an effort to ease joint pain.

Last year alone Island GPs wrote 1,317 prescriptions for glucosamine at a cost of £44,621.66 to the IOW NHS medicines budget. But following a recent meeting of senior local clinicians it was decided to advise GPs not to prescribe glucosamine on NHS prescriptions for osteoarthritis.

The Canadian study investigated whether the food supplement could prevent painful flare-ups in patients who had already been taking it for two years on average, with some signs of benefit. But the results showed that there was little difference compared with placebo. A total of 42 per cent of placebo patients experienced flare-ups in the six-month follow-up, compared with 45 per cent in the glucosamine group. In addition, subjects using glucosamine flared as quickly and as severely as those using a placebo, the researchers reported.

The study, which used medicinal grade glucosamine, a purified derivative from shellfish, follows a series of conflicting results on the benefit of glucosamine for osteoarthritis. However the sale of the supplement continues to see annual growth of around 10 per cent in the joint health category, with consumption of between 4,000 – 6,000 tons annually.

This is driven by rising numbers of arthritis sufferers. More than seven million adults in the UK, which represents 15 per cent of the population have long-term health problems due to arthritis and related conditions, and 550,000 have moderate to severe osteoarthritis in their knees.

When Island Life unearthed the Canadian findings, we spoke to Paul Jerram, the Head of Medicines Management for Isle of Wight NHS Primary Care Trust, asking for his reaction. Our request came just at the time when Island GPs were meeting to discuss whether glucosamine should be available on prescription.

Mr Jerram explained “Glucosamine is currently available as both food supplements and as licensed medicines. There are currently three glucosamine products which are licensed by the Medicines and Healthcare products Regulatory Agency (MHRA) to treat mild to moderate osteoarthritis (OA) of the knee.

“Medicine is a dynamic area of study with medical opinions changing regularly based on the latest clinical evidence. To obtain a license for a medicine, clinical trials must be undertaken – usually randomised clinical trials – to establish efficacy and safety. Efficacy is generally established using statistics and demonstrating that a medicine has a statistically proven positive effect on a condition is not the same as saying that a medicine has proven clinical value. Consequently we have a medicine, glucosamine, which has a statistically proven ability to improve osteoarthritis of the knee whilst there is considerable medical debate as to whether glucosamine has any clinical value at all.

“A further problem is that the results of trials are not consistent. A meta-analysis which combines the results of several studies that address a set of related research questions was undertaken in 2005 and found eight randomized clinical trials with glucosamine showing no benefit and 15 trials showing a benefit when using one set of pain measurement scales and no benefit at all when using other scales.

“Therefore it was concluded patients will show a benefit or not dependent on how the pain is measured. Also trials will usually compare glucosamine to a placebo – a sham or simulated medical intervention that can produce an improvement, called a placebo effect.

“Placebos in the treatment of pain have been shown to exert a considerable beneficial effect and are known to improve the perceived pain in more than 50 per cent of patients in some trials. Hence in a patient taking glucosamine it may be difficult to establish whether they are benefitting from the medicine or whether it is due to placebo effect.

“Recently a number of trials have been published on the value of glucosamine in the field of rheumatology. Glucosamine may be taken alone or in combination with chondroitin. In a recent meta-analysis published in the British Medical Journal this year, the authors stated ‘glucosamine supplements are not harmful and can be given to patients as long as the patients perceive a benefit and pay for their own treatment’.

“The NHS prescribing of glucosamine is not supported in Scotland (SMC) or in England (National Institute of Clinical Excellence) for the treatment of osteoarthritis.”

Mr Jerram confirmed “At a recent meeting of senior local clinicians the decision was made to advise GPs not to prescribe glucosamine on NHS prescriptions for osteoarthritis after considering latest clinical evidence and advice from a number of national and regional medical committees.”