Archive for the 'Miscellaneous' Category
May 18th, 2007 17:05:55
Dark Chocolate Can Be Good For You
Now, not only does chocolate taste good, but there is evidence that it actually can be healthy for you! A recent study presented at the annual meeting of the American College of Cardiology found that it seemed to help the functioning of endothelial cells. The research came from Yale University.
NOTE: they found that chocolate WITH NO SUGAR was the most beneficial. Have you ever tasted chocolate without sugar? Yuk! Unlikely that you will want to add this to your diet. The message may be that flavinoids help your blood vessels, not anything unique to dark chocolate.
http://www.forbes.com/forbeslife/health/feeds/hscout/2007/03/25/hscout602964.html
May 15th, 2007 1:05:51
Announcement: Family Medicine Update
Family physicians and other primary care providers will benefit from the new website Family Medicine Update at FamilyMedicineUpdate.com
This website is devoted to helping keep clinicians up-to-date with the latest medical news relevant to the practice of primary care medicine.
May 13th, 2007 10:05:09
Nuclear Heart Scan: Example Statistics
IF A NUCLEAR SCAN HAS A 90% sensitivity and
90% specificity of identifying angiographic
coronary artery disease, then:
When a patient has a low pretest probability
of disease (in this example, a 25% pretest
probability) and a positive nuclear test, the
odds are 3 to 1 that the patient has
coronary artery disease on angiography.
If there is a high pretest probability of
disease (75% chance of disease) and a normal
nuclear test, the odds are 3 to 1 that the
patient does NOT have coronary artery disease
on angiography.
If the pretest probability is low, and the
scan normal, the odds are 27 to 1 that there
is no significant angiographic evidence of
coronary artery disease.
Similarly, if the pretest probability is
high, and the scan is positive, the odds are
27 to 1 that angiographic disease is present.
Thus, DISCORDANT findings result in a 3 to 1
chance that the nuclear scan is “correct.”
CONCORDANT findings result in a 27 to 1
chance that the nuclear scan is “correct.”
If the pretest probability is intermediate (a
50% chance), then the odds are 9 to 1 that
the scan findings are “correct.”
HOWEVER….. it is important to note that the
nuclear scan is not intended to predict
angiographic coronary artery disease. It is
intended to identify stress induced ischemia.
These ARE NOT THE SAME THING.
The above statistics show that it isn’t
surprising to have a positive angiogram but a
normal nuclear heart scan or vice-versa. It
occurs quite often.
The value of the nuclear scan is in its
ability to predict future adverse cardiac
events. This is not affected by its
correlation with angiographic data.
Here are some more useful statistical
formulas:
The likelihood ratio (LR) given the nuclear
test is positive (assuming the sensitivity
and specificity values given above):
LR(+) = sensitivity / (1-specificity) =
90%/(1-90%) = 9
The likelihood ratio given the test is
negative:
LR(-) = (1-sensitivity) / specificity =
0.1/0.9 = 1 out of 9
The post-test odds, given the test is
positive:
Post-test odds (test +) = pre-test odds * LR
e.g. (pretest of 80%) = 4 * 0.9/(1-0.9) =
36:1
Post-test odds (test -): e.g. (pretest of
80%) = 4 * 0.1/0.9 = 0.4:1 = 2:5
ODDS = probability / (1-probability) e.g.
80%/20% = 4:1
PROBABILITY = odds / (odds+1) e.g. 4/(4+1) =
80%