Chance News 42: Difference between revisions

From ChanceWiki
Jump to navigation Jump to search
Line 35: Line 35:
6.  The tables below are taken from Jeffrey's summary of JAMA article.
6.  The tables below are taken from Jeffrey's summary of JAMA article.


<center><p><b>Physicians' Health Study II: Outcomes With Vitamin E vs Placebo</b>
<p><b>Physicians' Health Study II: Outcomes With Vitamin E vs Placebo</b>
 


<center>
<table border="1" cellpadding="3" cellspacing="1">
<table border="1" cellpadding="3" cellspacing="1">
<tr valign="top">
<tr valign="top">
<td><b>End point </b>
<td><b>End Point </b>
</td>
</td>
<td><b>Hazard Ratio (95% CI)</b>
<td><b>Hazard Ratio (95% CI)</b>
Line 51: Line 51:
<td><b>Composite primary end point</b>
<td><b>Composite primary end point</b>
</td>
</td>
<td>0.99 (0.89 &#8211; 1.11)
<td>1.01 (0.90 &#8211; 1.13)
</td>
</td>
<td>.91
<td>.86
</td>
</td>
</tr>
</tr>
Line 60: Line 60:
<td><b>Total MI</b>
<td><b>Total MI</b>
</td>
</td>
<td>1.04 (0.87 &#8211; 1.24)
<td>0.90 (0.75 &#8211; 1.07)
</td>
</td>
<td>.65
<td>.22
</td>
</td>
</tr>
</tr>
Line 69: Line 69:
<td><b>Total stroke</b>
<td><b>Total stroke</b>
</td>
</td>
<td>0.89 (0.74 &#8211; 1.07)
<td>1.07 (0.89 &#8211; 1.29)
</td>
</td>
<td>.21
<td>.45
</td>
</td>
</tr>
</tr>
Line 78: Line 78:
<td><b>Cardiovascular mortality</b>
<td><b>Cardiovascular mortality</b>
</td>
</td>
<td>1.02 (0.85 &#8211; 1.21)
<td>1.07 (0.90 &#8211; 1.28)
</td>
</td>
<td>.86
<td>.43
</td>
</td>
</tr>
</tr>
Line 86: Line 86:
</table>
</table>
<p></p>
<p></p>
<p>Among those treated with vitamin C, there were 10.8 events per 1000 person-years, and 10.9 events for those on placebo, again almost identical outcomes, and no associations in the secondary end points that would not be anticipated by chance, he added.</p>
<p><b>Physicians' Health Study II: Outcomes With Vitamin C vs Placebo</b>


<table border="1" cellpadding="3" cellspacing="1">
<table border="1" cellpadding="3" cellspacing="1">
<tr valign="top">
<tr valign="top">
<td><b>End Point</b>
<td><b>End point </b>
</td>
</td>
<td><b>Hazard Ratio (95% CI)</b>
<td><b>Hazard Ratio (95% CI)</b>
</td>
</td>
<td><b><i>P </i></b>
<td><b><i>P</i></b>
</td>
</td>
</tr>
</tr>


<tr valign="top">
<tr valign="top">
<td><b>Total mortality with vitamin E vs placebo</b>
<td><b>Composite primary end point</b>
</td>
</td>
<td>1.07 (0.97 &#8211; 1.18)
<td>0.99 (0.89 &#8211; 1.11)
</td>
</td>
<td>.15
<td>.91
</td>
</td>
</tr>
</tr>


<tr valign="top">
<tr valign="top">
<td><b>Total mortality with vitamin C vs placebo</b>
<td><b>Total MI</b>
</td>
</td>
<td>1.07 (0.97 &#8211; 1.18)
<td>1.04 (0.87 &#8211; 1.24)
</td>
</td>
<td>.16
<td>.65
</td>
</td>
</tr>
</tr>


<p><b>Physicians' Health Study II: Outcomes With Vitamin C vs Placebo</b>
<tr valign="top">
<td><b>Total stroke</b>
</td>
<td>0.89 (0.74 &#8211; 1.07)
</td>
<td>.21
</td>
</tr>


<tr valign="top">
<tr valign="top">
<td><b>Hemorrhagic stroke with vitamin E vs placebo</b>
<td><b>Cardiovascular mortality</b>
</td>
</td>
<td>1.74 (1.04 &#8211; 2.91)
<td>1.02 (0.85 &#8211; 1.21)
</td>
</td>
<td>.04
<td>.86
</td>
</td>
</tr>
</tr>


</table>
</table>
</center>
<p></p>
 
 




Why do these tables of odds-ratios support Gaziano's comments pertaining to vitamin C and vitamin E regarding cardiovascular mortality, total mortality and hemorrhagic stroke?
Why do these tables of odds-ratios support Gaziano's comments pertaining to vitamin C and vitamin E regarding cardiovascular mortality, total mortality and hemorrhagic stroke?

Revision as of 21:11, 17 November 2008

Quotation

Forsooth

"The potential public health benefits are huge" according to Dr. Paul M. Ridker lead author of The Jupiter Study referring to Crestor, a statin drug used to lower the risk of heart disease. "It's a breakthrough study. It's a blockbuster. It's absolutely paradigm-shifting" says Dr. Steven E. Nissen of the Cleveland Clinic who was not involved in the two-year study which consisted of about 18,000 people randomly assigned either to Crestor or to a placebo.

On the other hand, from Dr. Sidney M. Wolfe of Worst Pills, Best Pills, Crestor "can cause potentially serious kidney toxicity that is not seen with other cholesterol-lowering drugs, and it is the only drug of its type that caused rhabdomyolysis, a life-threatening adverse muscle reaction...there is no medical reason for you to be taking Crestor when there are three safer drugs on the market for reducing cardiovascular events."

Submitted by Paul Alper

Item 1

Vitamin Supplements

Chances are that the person next to you is currently taking vitamin C and/or vitamin E supplements in the belief that the vitamins are efficacious, or at the very least, not harmful. Unfortunately, that belief is now strongly challenged as can be seen in the article by Susan Jeffrey in Medscape Medical News. (To see this article put "vitamin c vitamin e jeffrey" in Google). She refers to an article in the Journal of the American Medical Association, November 12, 2008 by Dr. J. Michael Gaziano and Dr. Howard D. Sesso, et al

The objective of the study was “To evaluate whether long-term vitamin E or vitamin C supplementation decreases the risk of major cardiovascular events among men.” This “Physicians' Health Study II was a randomized, double-blind, placebo-controlled factorial trial of vitamin E and vitamin C that began in 1997 and continued until its scheduled completion on August 31, 2007. There were 14 641 US male physicians enrolled, who were initially aged 50 years or older, including 754 men (5.1%) with prevalent cardiovascular disease at randomization.” This study was done entirely by mail; the cost was roughly $120 to $130 per person per year.

This 2x2x2x2 factorial trial compared vitamin E with a placebo, vitamin C with a placebo or a multivitamin with a placebo. “The primary end point was a composite of major cardiovascular events, including nonfatal MI, nonfatal stroke, and cardiovascular disease death.” According to Gaziano, vitamin E –vs-placebo comparison had “virtually superimposable” curves. Likewise, almost identical outcomes for vitamin C-vs. placebo. Moreover, while “Neither vitamin E nor vitamin C had any effect on total mortality,” the “treatment with vitamin E was associated with an increased risk for hemorrhagic stroke, although the association was only marginally significant.”

Discussion

1. Dr. Barbara V. Howard, the current chair of the American Heart Association Council on Nutrition, commented that “people don’t eat a nutrient, they eat food.” She also said, “in these hard economic times, maybe we can save some money and not buy these supplements.” Annette Dickinson, a former president of a supplement industry group, says that more research is needed to determine whether a higher dose or different form of vitamin E would be more effective. Compare and contrast those two views.

2. There were roughly 120,000 person years of study. Calculate the approximate cost.

3. The sample consisted entirely of male physicians as did a previous study decades ago regarding aspirin as a means of preventing heart attacks. Why were physicians chosen for the trials? Women objected to the conclusions of that aspirin study. Why? Should they object to the vitamin C/vitamin E conclusions?

4. Most physicians are (still) white. Should the conclusions apply to non-white ethnic groups?


5. Study after study fails to show benefits from supplements, yet the supplement industry is booming. For example, there is a fourth cohort to this study, beta carotene vs placebo, which was reported in 2003 and showed no benefit from beta-carotene supplements. Explain this phenomenon whereby scientific studies indicate no benefit but the public keeps on purchasing supplements.


6. The tables below are taken from Jeffrey's summary of JAMA article.

Physicians' Health Study II: Outcomes With Vitamin E vs Placebo

End Point Hazard Ratio (95% CI) P
Composite primary end point 1.01 (0.90 – 1.13) .86
Total MI 0.90 (0.75 – 1.07) .22
Total stroke 1.07 (0.89 – 1.29) .45
Cardiovascular mortality 1.07 (0.90 – 1.28) .43

Among those treated with vitamin C, there were 10.8 events per 1000 person-years, and 10.9 events for those on placebo, again almost identical outcomes, and no associations in the secondary end points that would not be anticipated by chance, he added.

Physicians' Health Study II: Outcomes With Vitamin C vs Placebo

End point Hazard Ratio (95% CI) P
Composite primary end point 0.99 (0.89 – 1.11) .91
Total MI 1.04 (0.87 – 1.24) .65
Total stroke 0.89 (0.74 – 1.07) .21
Cardiovascular mortality 1.02 (0.85 – 1.21) .86



Why do these tables of odds-ratios support Gaziano's comments pertaining to vitamin C and vitamin E regarding cardiovascular mortality, total mortality and hemorrhagic stroke?