Snus use in Sweden: another reply to Tomar.

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I have previously discussed the role of snus in reducing smoking in Sweden, and criticized the IARC report’s coverage of this issue. Professor Scott Tomar (a member of the IARC committee) stated (as a comment to a posting criticising the new IARC monograph on smokeless tobacco):
“Using official Swedish data for smoking for 2004 (from the ULF survey conducted by Statistics Sweden), smoking quit rates (or what some call smoking quit ratios, defined as the proportion of ever smokers who are now former smokers), by age group and sex are:Age 16–24Men 13.2%Women 14.6%Age 25–44Men 37.8%Women 38.3%Age 45–64Men 54.5%Women 51.7% “

However, a colleague of mine based in Sweden (Lars Ramstrom), who is very familiar with Swedish surveys on tobacco use, has informed me that these figures on Swedish tobacco statistics are inaccurate in two ways:
1. They provide inaccurate numerical values for “the proportion of ever smokers who are now former smokers”
2. They inaccurately claim that the figures come from “the ULF survey conducted by Statistics Sweden”.

Statistics Sweden generally does not publish any figures on “the proportion of ever smokers who are now former smokers”. The main reason is that their ULF survey uses a questionnaire that does not include enough items to identify the subgroup “former occasional but never daily smokers who are now former smokers”. Since this subgroup must be part of both numerator and denominator of the calculation of such proportions, the ULF data are just unable to provide a basis for such calculations.

For this reason, we believe that the figures provided by Professor Tomar are likely to be inaccurate. However, the proportions in question can be calculated from other surveys that are performed by the Swedish research institute FSI, Research Group for Information and Societal Studies. These surveys are described in the literature (Ramström LM, Foulds J. Role of snus in initiation and cessation of tobacco smoking in Sweden. Tob. Control 2006;15;210-214). Using the same data base as the just mentioned article we get the following data:

Proportion of ever smokers (daily plus non-daily)
who are now former smokers
Age span Men Women
16-79 61% 54%
16-24 49% 42%
25-44 54% 53%
45-64 63% 55%
65-79 75% 68%

Professor Tomar made a point about the “similarity” between males and females quitting based on his original figures.
“Please explain why the quit rates in Sweden are so similar for men and women within each age stratum if snus had such a dramatic effect on cessation?”

In these figures we can see similarity in one age group only, 25-44. In this very age group a large proportion of women are planning or going through pregnancy and are thereby met the very forceful encouragement and treatment for quitting smoking that is very well established in the Swedish maternal health care system. This is a gender-specific condition that explains why this age group shows a different men/women comparison than the others.

The relevant question is rather opposite to the one asked by Professor Tomar:

Why are overall quit rates generally higher in men than in women in Sweden?

The answer is given by the following data picked up from the above mentioned article:
(These data refer to quit rate for daily smoking, while the data above refer to quit rate for all smoking. Therefore the numerical values differ a little)

Proportion of ever daily smokers
who are now former smokers
Men Women
Overall 59% 49%
With a history of daily snus use 72% 71%
Without history of daily snus use 51% 48%

These data illustrate that gender comparisons have to be made between truly comparable subgroups in order to yield meaningful conclusions.

In each one of the two lower lines there are comparisons between men and women who are comparable with respect to snus use. In each case there is no difference.

In each one of the gender columns the two lower lines give gender-specific comparisons indicating the influence of snus use. Both for men and women there are large differences in quit rate according to presence or absence of a history of snus use.

The above observations demonstrates that the overall difference between men and women does not stem from factors related to gender itself but to the fact that snus use, as a cessation promoting factor, is more prevalent among men than among women.

In summary, contrary to Professor Tomar’s thesis, the Swedish statistics on smoking cessation suggest that snus use is having a substantial effect in promoting cessation of smoking among men. Of course this is self evident from the simple fact that 24-30% of male Swedish ex-smokers used snus to quit smoking. My thanks to Lars Ramstrom for providing clarification on the pattern of tobacco use in Sweden.

Incidentally, the issue of snus for smoking cessation was recently debated in the British Medical Journal, at:
http://www.bmj.com/cgi/content/full/336/7640/358

For the record (again), I don’t believe that health professionals should recommend snus to their patients. I believe that we have medicines and counseling that can be effective treatments for addiction to cigarettes (or at least as efficacious as snus) and that these are what we should be recommending to patients. However, I do believe that the public should have accurate information about the relative risks of snus and cigarettes. Currently the public underestimates the risks from cigarettes, relative to snus or nicotine replacement therapy.
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About the Author


MA, MAppSci, PhD

Dr. Jonathan Foulds is an expert in the field of tobacco addiction.

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