In an article in the Canadian Journal of Cardiology,
researchers report increased risk for cataracts in patients treated with
statins. An accompanying editorial discusses the history of statins and
positions this new study in the context of conflicting results from previous
analyses of purported adverse effects due to statin use.
In previous studies the association between statin use and cataracts
has been inconsistent and controversial. The current study used data from the
British Columbia (BC) Ministry of Health databases from 2000-2007 and the IMS
LifeLink U.S. database from 2001-2011 to form two patient cohorts. The BC
cohort was composed of female and male patients; 162,501 cases were matched
with 650,004 controls. The IMS LifeLink cohort was comprised of males only,
aged 40-85; 45,065 cases were matched with 450,650 controls. Patients using
statins for more than a year prior to initial ophthalmology examination were
identified. Diagnosis and surgical management of cataracts were followed.
In the BC cohort, there was about a 27% increased risk of developing
cataracts requiring surgical intervention (Adjusted Risk Ratio, RR =1.27). In
the IMS cohort, the increased risk was only 7%, but still statistically
significant.
The adjusted RRs for long-term regular use of specific statins in the
BC cohort ranged from 1.14 to 1.42. In the IMS cohort, the adjusted RRs for
individual statins varied within a narrow range from 1.03 to 1.14. The investigators
did not determine whether certain statins were worse than others, but most
confidence intervals overlapped suggesting a class effect.
Lead investigator G.B. John Mancini, MD, of the Department of
Medicine, Faculty of Medicine, University of British Columbia, Vancouver,
Canada, states that, "Further assessment of the clinical impact of this
relationship is recommended, especially given increased statin use for primary
prevention of CVD and the importance of acceptable vision in old age where CVD
is common. Future studies addressing the possible underlying mechanisms to
explain this association are also warranted. However, because the RR is low and
because cataract surgery is both effective and well tolerated, this association
should be disclosed but not be considered a deterrent to use of statins when
warranted for CV risk reduction."
In an accompanying editorial, Steven Gryn, MD, FRCPC, and Robert A.
Hegele, MD, FRCPC, of the Department of Medicine, Schulich School of Medicine
and Dentistry, Western University, London, Ontario, Canada, echo the need for
balance.
They write, "Any medication that has beneficial effects has
potential adverse effects; weighing the benefits against the risks is an
integral part of the informed consent process, and is central to any decision
to initiate treatment. Among patients who are at high CVD risk, like most of
those seen by cardiologists...the prevention of CVD, stroke, and their
associated morbidity and mortality vastly outweighs the risk of cataracts. Even
among lower risk patients, for whom the benefit-risk ratio is less dramatic,
most patients would still probably prefer having to undergo earlier
non-life-threatening cataract surgery over suffering a major vascular
event."
In
any observational study, there can be unknown confounders that could introduce
bias. Both the study itself and the commentary note this weakness, but both
agree that this study, while not putting the issue to rest, does add
significantly to the accumulated knowledge about the statin-cataract connection.
However, as Dr. Hegele notes, "A randomized double-blinded
placebo-controlled clinical trial is the best way to mitigate confounding, and
such studies so far have shown no association of statins with cataracts."
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