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[sebastian_dangerfield]

Originally posted by Replaced_Texan
Warning: math

Relative risk is the ratio of the percentage of the exposed population with a disease over the percentage of the non-exposed population with the disease. Usually the populations are from the same general geographic area and the same general age. If there were no association with exposure, the relative risk would equal 1. If the exposure were good for you (i.e. less people get sick) the relative risk would equal <1. If the exposure is bad for you the RR would be >1.

An RR of 1.9 means that a person exposed is 90% more likely to get the disease than someone not exposed. It's up to you to decide if that's an acceptable risk.

The reason I keep telling you to go back and read the report is that no one study can tell you the relative risk of getting lung cancer from second hand smoke. It can only tell you the RR for that particular study. The RRs range from around 0.95 to 12.6 (in males in India, weird), but it seems that they tend to hover around 1.35 or so, which is is a 35% greater cancer risk than for people not regularly exposed to second hand smoke. Nowadays, they're fine tuning the studies to look at the levels of exposure over time.

You were bitching about the media dumbing everything down to scare people, but you didn't go and read the report yourself to find out what the real story (as far as anyone can tell based on current evidence) is.

You've been bitching that anyone can prove anything in a study. Yes, that's true. That's why there are over 50 studies and five or so different design methods (cohort, case control, pooled analysis, etc) looking at the effects on lung cancer cases in the report, and that's why the report has a LOT of conclusions that are worded like this: "The evidence is inadequate to infer the presence or absence of a causual relationship between secondhand smoke exposure and the risk of cervical cancer among lifetime nonsmokers." It just so happens that lung cancer doesn't get a "inadequate to infer"; it gets a "the evidence is sufficient to infer".

You started this whole thing by saying that no one has ever proven that second hand smoke causes lung cancer (ignoring all of the other diseases associated with second hand smoke). I said, uh, yeah, actually they have, repeatedly and I've given you several cites as to where they have, including a very comphrensive summary of ALL of the studies on the subject. Now you're quibbling over the numbers.

Frankly, I think it's irresponsible to refuse to publish something because the RR is too low, but I did note that there was only one study from the NEJM in the bibliography. Good science should show that there is no or little association as well as showing that there is an association.

Warning: Simplification.

I understand how an RR works. I also understand that an RR of 1.9 is a lousy RR, and a lot of reputable researchers wouldn't even include it (as I noted).

I understand the study and did read what you cited. An RR of 1.9 for a disease with an exceedingly low incidence in non-smokers means a non-smoker in the presence of smokers minimally increases a very insignificant risk.