Alert over simvastatin rhabdomyolysis risk
GPs have called for an urgent review of ‘outdated' NICE guidelines on hyperlipidaemia after an analysis showed a 12-fold increased risk of severe muscle damage with simvastatin 80mg.
Researchers showed patients taking simvastatin across its doses were 2.6 times more likely to suffer rhabdomyolysis than patients taking other statins, in the first indication of a potential raised incidence of rhabdomyolysis in the community with simvastatin.
The findings follow the results of the UK SEARCH trial in 2010, which found a rate of rhabdomyolysis of 0.2% in patients taking simvastatin 80mg, compared with 0% in the simvastatin 20mg group.
Following this study, the MHRA warned GPs to avoid prescribing the highest dose of simvastatin, using the 80mg dose only in patients with severe hypercholesterolaemia, or a high risk of complications where the benefits were expected to outweigh the risks.
But the 80mg dose continues to be recommended in NICE guidance for patients who are not controlled on lower doses, and latest prescribing figures from the NHS Information Centre reveal over 550,000 prescriptions of simvastatin 80mg were made in primary care in England last year.
The US researchers compared estimated statin prescribing rates from pharmacy data in the Group Health Co-operative in Washington state over four years.
They found 29 validated cases of rhabdomyolysis and 18 cases of myopathy, equating to an overall statin-related incidence rate of 10.1 people and 6.3 people per 100,000 person-years, respectively.
Simvastatin overall had an incidence of 13.5 per 100,000 person-years.
At a dose of 80mg, it was associated with an rhabdomyolysis incidence of 64.8 per 100,000 person-years, a 12.2-fold increase in risk compared with lower doses of 20-39mg.
Study leader Dr James Floyd, a lecturer in epidemiology at the University of Washington, said: ‘Most of the risk of high-dose simvastatin is up front, within the first year.'
Dr Rubin Minhas, clinical director of the BMJ Clinical Evidence Centre and a GP in Hoo, Kent, said future NICE guidance should be changed in line with the evidence: ‘The risk of muscle damage adds to the evidence for considering atorvastatin at higher doses.'
Dr Ahmet Fuat, a cardiology GPSI in Darlington, said: ‘This study highlights the folly of the "fire and forget" approach to monitoring bloods in statin takers suggested by outdated NICE guidelines.'
JAMA 2012, online 18 April