During the past ten years the sale of snuff in Norway has increased, while the sale of smoking tobacco has declined. This has happened parallel to the introduction of smoking restrictions in public areas and growing concern about the health risks associated with smoking. Approximately 300,000 used snuff in 2003/2004. Of these about 140,000 used snuff every day. The majority of snuff users are men under 45 years. The age at starting is decreasing. Female users are still few, but the number is expected to rise. Situations where the consumption rises and the health effects are not clarified, generates new challenges.
To systematically review, assess and summarize the epidemiological evidence concerning the health effects and dependency associated with snuff consumption, and the role of snuff in smoking initiation and smoking cessation.
Systematic search was undertaken in the Cochrane Library (Cochrane Database of Systematic Reviews, DARE, CENTRAL (earlier Cochrane Controlled Trials Register), HTA (INAHTA)), Medline, Embase, Psycinfo, Cinahl, Swemed, Current Controlled Trials, from 1872 to 7 February 2005. References of identified trials and relevant reviews were also screened.
Epidemiological studies were selected if they were systematic reviews, randomised controlled trials, controlled trials, cohort studies or case-control trials, if they included users of snuff or smokeless tobacco, and measured one of the following: nicotine absorption, toxin exposure, mortality, cancer, cardiovascular effects, diabetes, pregnancy outcomes, oral health, dependence, smoking initiation, smoking cessation (or their synonyms).
An evaluation was not performed of documentation from animal experiments with snuff or components of snuff. The member of the expert group Erik Dybing disagrees that documentation from animal experiments was not included as a basis for the group’s conclusions.
Data collection and analysis
The literature search gave 1040 hits. Two authors independently screened the abstracts, reviewed 207 publications in full text, and assessed the methodological quality of 59 studies using the Norwegian Knowledge Centre for Health Services’ checklists. 29 studies were excluded due to irrelevant problem formulation, outcome or study design.
Because the study population, interventions and outcome measures were heterogeneous, a rating system with level of evidence was used. Scandinavian and American studies were assessed separately due to reported differences in some harmful constituents of snuff products sold in Scandinavia and USA.
A systematic review was carried out on the 30 studies that met the inclusion criteria. All the studies were of high or medium methodological quality. Many of the studies however 60 included few individuals who exclusively used smokeless tobacco, and combined use of smokeless tobacco and cigarettes appeared frequently. In addition, information about exposure duration and dose was often lacking. There was overall limited epidemiological evidence of health effects associated with smokeless tobacco. There was strong evidence that smokeless tobacco produces dependency. There was conflicting evidence about smokeless tobacco and its role in smoking initiation and smoking cessation.
Keywords: Tobacco, Smokeless; Dependency (Psychology); Snuff.
Copyright ©2005 by The Norwegian Institute of Public Health (NIPH).
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