Wednesday, November 17, 2010
American Evidence that Snus Is An Effective Substitute
Scientists from the University of Minnesota Tobacco Use Research Center have just published the results of a clinical trial from 2006-7 showing that RJ Reynolds’ Camel Snus and Philip Morris’ Taboka (a precursor of Marlboro Snus) were viable substitutes for cigarettes. The trial was conducted by Michael Kotlyar and colleagues; the results are published in Cancer Epidemiology and Biomarkers (abstract here).
Kotlyar recruited smokers who were interested in quitting, and assigned them to use one of three products: 4 milligram nicotine gum or lozenge, Camel Snus or Taboka (participants had a choice of various flavors for each product). Participants used only 1 or two products per day during a one-week sampling period; for the next four weeks, they used the product at least 6 to 8 times daily. During week 5, participants were required to reduce consumption of the substitute; by the end of that week they had to be completely tobacco- and nicotine-free.
There were several interesting results. First, all participants in all groups had a reduction in exhaled carbon monoxide, clearly demonstrating that they smoked less than before the study. Participants in all groups had a reduction in the urine concentration of two chemicals that are considered carcinogens, abbreviated here as NNN and NNAL. The reductions were statistically significant except for NNN in Camel Snus users (p = 0.07).
Overall craving and withdrawal scores decreased over the 4 weeks in all groups, with no differences between the groups.
Continuous abstinence rates over the 4 treatment weeks varied from 33% (Taboka) to 43% (Camel Snus). Two weeks after the treatment ended, 39% of the Taboka group, 47% of the Camel Snus group and 56% of the nicotine group were not smoking, but these percentages dropped to 23%, 31% and 33% respectively after ten weeks of complete abstinence.
One possible reason for the precipitous drop in the smoke-free percentages was the insistence on abstinence after 4 weeks. If this philosophy prevails, it will guarantee that smokeless products are no more effective than pharmaceutical nicotine, which has a documented failure rate of 93% (evidence here).
There is evidence that the FDA is starting to think about offering smokers “long-term” nicotine substitution (review a symposium on the topic was held on October 26-27 here), which is a strategy I called “nicotine maintenance” in 1999 (here). I recommend that readers look at the FDA presentations, especially the one by Neal Benowitz (here). He indicates that the best information about the long-term risks of nicotine come from the epidemiologic studies of Swedish snus use.
There were other interesting aspects of the Minnesota study. The Taboka group smoked significantly more than those using nicotine or Camel Snus. It is possible that Taboka, which had very low nicotine levels, simply didn’t satisfy smokers.
A total of 1,159 smokers responded to advertisements for the study. According to the researchers, 800 “were able to be reached and were screened over the telephone,” and 429 qualified and were interested in participating. Another 212 did not show up for the orientation. The attrition didn’t stop there: 211 smokers were enrolled in the study but only 130 were randomized to one of the three groups. Just 80 participants completed the 4-week treatment period and the one-week transition to abstinence.
These numbers represent one of the biggest challenges of clinical trials, especially in the field of risky behaviors like smoking. The 80 participants who completed the study represent only 6.9% of the smokers who originally responded, so they are an especially motivated group. That has been one of the problems with quit-smoking trials: It is impossible to generalize their results because they are from a highly selected population that is not representative of smokers in general.
In the past, I have criticized the Minnesota group for publishing biased and distorted studies about smokeless tobacco (here and here). But this is a fair and balanced report of the potential for smokeless tobacco as a substitute for cigarettes.