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Benefits of Statins in Healthy Elderly Subjects
Accepted Manuscript Letter to the Editor: Benefits of Statins in Healthy Elderly Subjects. What Is the Number Needed to Treat? Axel F. Sigurdsson, MD PII:
S0735-1097(14)01810-5
DOI:
10.1016/j.jacc.2014.02.605
Reference:
JAC 20040
To appear in:
Journal of the American College of Cardiology
Received Date: 14 January 2014 Accepted Date: 3 February 2014
Please cite this article as: Sigurdsson AF, Letter to the Editor: Benefits of Statins in Healthy Elderly Subjects. What Is the Number Needed to Treat?, Journal of the American College of Cardiology (2014), doi: 10.1016/j.jacc.2014.02.605. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Letter to the Editor: Benefits of Statins in Healthy Elderly Subjects. What Is the Number Needed to Treat?
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Axel F Sigurdsson, MD Department of Cardiology Landspitali University Hospital Hringbraut 101 Reykjavik, Iceland E-mail: [email protected]
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No Conflicts of Interest
1
ACCEPTED MANUSCRIPT I read with interest the paper by Savarese et al. (1) reporting the results of a meta-analysis of the benefits of statins in elderly subjects without established cardiovascular disease. One of the biggest questions facing clinical cardiology today is the decision on which individuals to treat with statins in primary prevention. Because statins are not without side effects we have
RI PT
to be sure that the risk of harm does not outweigh the presumed benefits.
In their meta-analysis, Savarese et al. came to the conclusion that statins significantly reduce the incidence of MI and stroke, but do not significantly prolong survival in the short-term.
SC
They believe their meta-analysis provides “first-time evidence that the benefits of statins on major CV events extends to people > 65 years without CV disease”.
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MI occurred in 2.7% of subjects allocated to statins compared with 3.9% of those on placebo during a mean follow-up of 3.5 years. This corresponds to a relative risk reduction of 39.4%. Stroke was reported in 2.1% of subjects randomized to statins compared with 2.8% on placebo during the same mean follow-up period. This corresponds to a relative risk reduction
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of 23.8%
The authors have calculated that 24 patients needed to be treated for 1 year to prevent 1 MI, and that 42 patients needed to be treated for 1 year to prevent 1 stroke. The authors repeat
EP
these numbers in the final chapter of the paper where cost-benefit evaluation of statin
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treatment in elderly people is discussed. It appears that the authors have made an erroneous calculation. The annual MI rate was 1.1% and the annual rate of stroke was 0.8% in patients allocated to placebo. Considering a relative risk reduction of 39.4% and 23.8 respectively, the absolute risk reduction for 1 year is approximately 0.43% for MI and 0.19% for stroke. The number needed to treat (NNT) is the inverse of the absolute risk reduction (ARR): NNT = 100/ARR.
2
ACCEPTED MANUSCRIPT By using data from the paper I have calculated that the NNT for one year to prevent one MI and one stroke respectively may be approximately 10 times higher than that reported in the paper, given that NNT is constant over time. In my opinion the most appropriate approach would have been to report the NNT for the
RI PT
mean follow-up of 3.5 years, which would have been approximately 83 to prevent one MI and 142 to prevent one stroke. This is the most commonly used approach in similar studies. The NNT is very important when assessing the efficacy of statin therapy. Therefore it is
SC
essential that the authors do a recalculation of their data and report the correct NNT numbers.
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EP
TE D
M AN U
They may also have to reconsider the main conclusions of their meta-analysis.
3
ACCEPTED MANUSCRIPT References: 1. Benefits of Statins in Elderly Subjects Without Established Cardiovascular Disease.
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EP
TE D
M AN U
SC
RI PT
Savarese G, Gotto AM, Paolillo S et al. J Am Coll Cardiol 2013;62:2090-9.
4
S0735-1097(14)01810-5
DOI:
10.1016/j.jacc.2014.02.605
Reference:
JAC 20040
To appear in:
Journal of the American College of Cardiology
Received Date: 14 January 2014 Accepted Date: 3 February 2014
Please cite this article as: Sigurdsson AF, Letter to the Editor: Benefits of Statins in Healthy Elderly Subjects. What Is the Number Needed to Treat?, Journal of the American College of Cardiology (2014), doi: 10.1016/j.jacc.2014.02.605. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Letter to the Editor: Benefits of Statins in Healthy Elderly Subjects. What Is the Number Needed to Treat?
RI PT
Axel F Sigurdsson, MD Department of Cardiology Landspitali University Hospital Hringbraut 101 Reykjavik, Iceland E-mail: [email protected]
AC C
EP
TE D
M AN U
SC
No Conflicts of Interest
1
ACCEPTED MANUSCRIPT I read with interest the paper by Savarese et al. (1) reporting the results of a meta-analysis of the benefits of statins in elderly subjects without established cardiovascular disease. One of the biggest questions facing clinical cardiology today is the decision on which individuals to treat with statins in primary prevention. Because statins are not without side effects we have
RI PT
to be sure that the risk of harm does not outweigh the presumed benefits.
In their meta-analysis, Savarese et al. came to the conclusion that statins significantly reduce the incidence of MI and stroke, but do not significantly prolong survival in the short-term.
SC
They believe their meta-analysis provides “first-time evidence that the benefits of statins on major CV events extends to people > 65 years without CV disease”.
M AN U
MI occurred in 2.7% of subjects allocated to statins compared with 3.9% of those on placebo during a mean follow-up of 3.5 years. This corresponds to a relative risk reduction of 39.4%. Stroke was reported in 2.1% of subjects randomized to statins compared with 2.8% on placebo during the same mean follow-up period. This corresponds to a relative risk reduction
TE D
of 23.8%
The authors have calculated that 24 patients needed to be treated for 1 year to prevent 1 MI, and that 42 patients needed to be treated for 1 year to prevent 1 stroke. The authors repeat
EP
these numbers in the final chapter of the paper where cost-benefit evaluation of statin
AC C
treatment in elderly people is discussed. It appears that the authors have made an erroneous calculation. The annual MI rate was 1.1% and the annual rate of stroke was 0.8% in patients allocated to placebo. Considering a relative risk reduction of 39.4% and 23.8 respectively, the absolute risk reduction for 1 year is approximately 0.43% for MI and 0.19% for stroke. The number needed to treat (NNT) is the inverse of the absolute risk reduction (ARR): NNT = 100/ARR.
2
ACCEPTED MANUSCRIPT By using data from the paper I have calculated that the NNT for one year to prevent one MI and one stroke respectively may be approximately 10 times higher than that reported in the paper, given that NNT is constant over time. In my opinion the most appropriate approach would have been to report the NNT for the
RI PT
mean follow-up of 3.5 years, which would have been approximately 83 to prevent one MI and 142 to prevent one stroke. This is the most commonly used approach in similar studies. The NNT is very important when assessing the efficacy of statin therapy. Therefore it is
SC
essential that the authors do a recalculation of their data and report the correct NNT numbers.
AC C
EP
TE D
M AN U
They may also have to reconsider the main conclusions of their meta-analysis.
3
ACCEPTED MANUSCRIPT References: 1. Benefits of Statins in Elderly Subjects Without Established Cardiovascular Disease.
AC C
EP
TE D
M AN U
SC
RI PT
Savarese G, Gotto AM, Paolillo S et al. J Am Coll Cardiol 2013;62:2090-9.
4