And don't get me started on how it pained my soul to watch Newt's anti-Mitt documentary, which was like a snuff film combined with crush porn combined with an episode of Mutual of Omaha's Wild Kingdom.
a Fuller details of the studies are given in Tables 1 and 2 b ST implies smokeless tobacco unspecified or combined snuff use or chewing c Ever, former and current ST are compared with never ST.
Combined use of snuff and cigarettes among male adolescents has been associated with higher levels of nicotine dependence than cigarettes alone [ 13].
The question about tobacco use combined smoking and use of snuff.
Given that smoking has a much greater effect on lung cancer risk than on pancreatic cancer risk [ 36, 37], any residual confounding in the estimated ever vs. never snuff use for smokers and non-smokers combined should be substantially greater for lung cancer than for pancreatic cancer.
In a few studies where information was available on chewing and on snuff but not on joint use, approximate estimates for combined smokeless use were obtained assuming that no-one used both products.
While some bias may be present for this reason, it seems implausible that it could possibly explain the huge difference between the estimates for ever vs. never snuff use of 0.90 (0.70–1.20) for smokers and non-smokers combined and that of 2.00 (1.20–3.30) for never smokers.
The studies vary as to whether they report results for chewing tobacco and snuff separately [ 13, 15, 20], for chewing tobacco only [ 12, 21], or for combined ST use based on chewing tobacco or snuff [ 14, 16].
In five studies (11, 14, 23, 28, 29) combined estimates for smokeless tobacco use were calculated approximately assuming that noone chewed tobacco and used snuff.
Notably, for the Norway Cohorts Study by Boffetta et al [ 10], reference was made to a relative risk [RR] for ever use of snuff of 1.67 (95% confidence interval [CI] 1.12 2.50), which was based on results for smokers and non-smokers combined with adjustment for smoking, with no mention made of the RR of 0.85 (95% CI 0.24 3.07) specifically for never smokers.
