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GPs divided on obesity drugs efficacy

By Nigel Praities

A new study has provoked fierce debate among GPs after finding anti-obesity treatments frequently failed to promote clinically significant weight loss.

Researchers reviewed data from randomised controlled trials and concluded orlistat, sibutramine and rimonabant were of only ‘modest' help in long-term weight loss.

Average weight loss across treatments was less than 5%, below the thresholds for recommending a continuation of therapy by NICE, concluded the researchers in the BMJ.

NICE advises anti-obesity drugs should be discontinued if patients have not lost at least 5% of their initial body weight after three months.

Study leader Professor Gareth Williams, professor of medicine at the University of Bristol, said the studies showed the jury was still out on the long-term efficacy and safety of anti-obesity treatments. He added that they should not be given to patients who cannot lose weight through lifestyle changes alone

‘If patients can't get on and take responsibility for their own lives, then flinging a pill at them is not going to do any useful work at all,' he said.

Professor Williams also warned of ‘insidious collateral damage' if GSK was successful in its bid to make orlistat available OTC in Europe.

Dr David Haslam, chair of the National Obesity Forum, slammed the BMJ meta-analysis for being ‘full of errors' and called it a ‘very bad' paper. ‘Five percent weight loss is very clinically significant. What they are doing here is actually looking at average weight loss and some may not lose any weight but others may lose 10 or 20%.'

He supported moves to make orlistat available OTC, provided the lifestyle message was not diluted. But he warned GPs not to use rimonabant in patients with a history of mental problems.

‘There is a risk-benefit profile to these treatments and we must be alert to those risks,' he said.

Dr Peter Stott, a GP in Surrey and former board member of the National Obesity Forum, said the reduction in calories from anti-obesity treatments was equivalent to ‘a slice and a half of dry bread' per day, but they were useful for patients whose weight loss had slowed and needed new motivation.

Waist Key findings of the analyses

Anti-obesity treatments reduced weight by an average of less then 5kg, compared with placebo
Rucker et al, BMJ online 2007

Patients on rimonabant were 40% more likely to have a serious adverse event and 2.5 times more likely to discontinue treatment because of depressive mood disorders than patients on placebo
Christensen et al, The Lancet online 2007

Meanwhile an analysis in the Lancet showed that patients on rimonabant had a 40% greater risk of serious adverse events than those on placebo. Patients on rimonabant were also significantly more likely to discontinue medication be-cause of depression or anxiety.

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