Re: Epidemiology

[hflong@postoffice.pacbell.net]

Dear HPs,

It pains me to point out a problem with a conclusion I like (radiation helped

radiologists) from a researcher for whom I have the highest respect ( John

Cameron), but I must to be consistent. So I enclose the comment I sent John.



"I would question that the radiologist study is as impressive as the NSWS because

of differences between radiologists and other physicians. When I checked with my

friend Bob Cihak, Past President of our Association of American Physicians and

Surgeons (more scientific than political like AMA) and a radiologist, he said,

"Yes, I for one chose radiology to avoid the 80 hour work weeks of other

residencies and specialties."

Radiologists are less type ":A", adrenergic, subject to heart attacks. Using

other physicians as controls is as unsatisfactory as Field using c35% smokers as

controls for lung cancer cases with c95% smokers."



Cameron is promoting a placebo-controlled trial, and Field made great effort to

match  controls, but it is difficult. You can't really PROVE anything to a

properly skeptical epidemiologist, even using placebo, and with some reason. I

give the current example of estrogen-progestin being declared bad for the heart by

the huge Women's Health Initiative at many large Universities because of 6 more

cases (1.3 times placebo). They did not report separately the ever-smokers, who

had about 4.0 times never-smoker cardiovascular deaths, when both took

estrogen-progestin after age 45 ( Layde PM, Beral V Further analyses of mortality

in oral contraceptive users; Royal College of General Practitioners’ Oral

Contraception Study Lancet 1981). WHI didn't report data separated for

ever-smokers. When they do (quietly, with embarassment), I predict never-smokers

will be found to have significantly LESS heart disease when taking

estrogen-progestin than placebo. What is true for some (radiologists) may not be

true for others who seem the same (physicians generally).



I believe most Americans don't have enough ionizing radiation. We need placebo

controlled trials. Will Bill Field and John Jacobus sign on to the ethics?



Howard Long



Gary Isenhower wrote:



> I agree with Jerry 100%.  Also, the discrepancy between radiologists and

> non radiologists is very remarkable - so much so, that the lack of any

> comment on it is equally remarkable.

>

>     _______________________________________________

>

>         Gary Isenhower

>         713-798-8353

>         garyi@bcm.tmc.edu

>

> Jerry Cohen wrote:

> >

> >     Although I took a few courses in the subject many  years ago while in

> > grad school, I would also not consider myself an epidemiologist. However, I

> > don't believe that the practice of epidemiology  requires abandonment of

> > common sense.

> >     Of course, it is best to base studies on the best data one can obtain.

> > Sometimes such data are simply unavailable and reasonable assumptions must

> > be substituted.

> > In this regard, precise dosimetric data on radiation exposure levels for

> > radiologists vs.

> > non radiologist physicians are  unavailable. However, isn't it reasonable to

> > assume that

> > radiologists generally experience significantly greater radiation exposures

> > than do other specialists--- or that they do not smoke  significantly more

> > or less? Similarly, lacking precise data, isn't it reasonable to assume that

> > smoking habits in high vs. low radon areas are about the same?

> >

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