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From: werner@aecom.UUCP (Craig Werner)
Newsgroups: net.med
Subject: Re: Re: Risk factors
Message-ID: <1955@aecom.UUCP>
Date: Sat, 19-Oct-85 00:58:41 EDT
Article-I.D.: aecom.1955
Posted: Sat Oct 19 00:58:41 1985
Date-Received: Mon, 21-Oct-85 22:38:37 EDT
References: <1939@aecom.UUCP> <796@terak.UUCP>
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Organization: Albert Einstein Coll. of Med., NY
Lines: 33

> Which brings up a universally overlooked point when "risk factors" are
> quoted...
> 
> --  Does altering the risk factor have any effect?
> Doug Pardee -- CalComp 

Two criteria for true risk factors:
	1. The correlation should be statistically significant and of course,
reproduceable.
	2. It should be dose-dependent.

For instance, in american males, heart disease is related to smoking both by
the number of years smoked and number of packs (it can be expressed as pack-
years.) So quitting smoking does help.
	As for cholesterol, the higher one's LDL, the higher one's chance of
dying early from heart disease.  In fact, the dose-relation is not linear -
it is more like hyperbolic.  And a "normal" cholesterol level of 260 is
probably far too high, and "normal" should be revised.  (incidentally, the
upper limit of normal is defined as 2 std deviations above mean, so by
definition, 95% of all people are normal or below.  Clearly this is not the
case clinically, just statistically.) The recently completed Lipid Research
Study has just shown that lowering blood lipid DOES lower risk enough to
justify medical intervention.
	As for high blood pressure, with one small exception, lowering one's
pressure and keeping it low, lowers one mortality risk.  This is probably the
best documented finding in all interventional epidemiology.


-- 

				Craig Werner
				!philabs!aecom!werner
 "Comedy, like Medicine, was never meant to be practiced by the general public."