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Statins and myopathy
The day following a relevant television documentary
(Lipex, Close-Up, TV1, 1 November
2005, compiled by Ian Sinclair), I was consulted by a patient with symptoms of
angina. He was interested in protective measures to reduce risk but explanations
of how treatment with a low-medium dose of a statin might reduce this by about 1
in 10 over 5 years set against a risk of myopathy of 1 in 10,000 were to no
avail as his wife now considered the medication “far too dangerous”.
I am sure this situation was echoed in consulting rooms
around New Zealand, despite the programme including factual information on risks
and benefits. Urban myths about statins (fuelled by talkback radio) are
prominent and will no doubt be further stimulated, but there are issues
requiring reflection.
The major preventive benefit (in those at sufficiently high
risk) and extremely low adverse event rate of statin therapy were restated in
the recent review of placebo-controlled trials.1 We do have to be mindful that
these trials generally used fixed low-medium doses of statins while higher doses
and combination therapies increasingly being urged2 could have different
benefit/risk equations. The recently published
Z phase of the A-Z Trial3 documented
nine cases of myopathy (CK >10 times the upper normal limit) among 2263
patient taking simvastatin 80 mg daily for 6 to 24 months (a rate of about 1 in
250).
Atorvastatin, the only other statin available in New Zealand
(by Special Authority), even when used in highest recommended doses (80 mg/day)
seems to be associated with low rates of myopathy.4 Additional
concomitantly-used drugs (including erythromycin, calcium antagonists,
cyclosporine, some antifungals and fibrates), diet (notably grapefruit juice),
and other patient-related factors may interfere with metabolic breakdown (or
otherwise interact with statins) and increase the risk of myopathy. Not all
these factors can be reliably avoided in routine clinical practice and are more
likely encountered there than in tightly controlled trials.
Perceptions of risk and benefit of medical interventions
among health professionals, patients, and the public often show significant
variance from what has been reliably documented.5 Coverage in the media
highlighting particular problems, even when figures given are reasonably
factual, is one contributor to these potential distortions. We should strive to
put across a correctly balanced view of benefits of risks of proposed therapies
and interventions.
Stewart Mann
Associate Professor Department of Medicine Wellington School of Medicine and Health Sciences, University of Otago Wellington (stewart.mann@otago.ac.nz) Disclosures:
I have attended meetings sponsored by Pharmaceutical Companies who market
statins in New Zealand (Merck, Sharp and Dohme (NZ) Ltd, Pfizer (NZ) Ltd). I am
a member of the Cardiovascular Subcommittee of the Pharmacology and Therapeutics
Advisory Committee to
PHARMAC.
References:
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