SNUS AS A VIRTUALLY SAFE ALTERNATIVE TO SMOKING: A REVIEW OF THE EVIDENCE Peter Lee and Jan Hamling P. N. Lee Statistics & Computing Ltd PeterLee@pnlee.co.uk 27 th April 2010 Snus and health_2.ppt 1
SNUS Snus is Swedish-type moist snuff Snus is made from finely ground dry tobacco, mixed with aromatic substances, salts, water, humidifying agents and chemical buffering agents A pinch (dip) is placed between the gum and upper lip, often for 11 to 14 hours/day Nicotine exposure from snus and cigarette smoking is similar Snus contains tobacco specific nitrosamines at low levels 2
SNUS Snus is on sale in Sweden but banned in other EU countries In 2005 snus represented 54% of tobacco sold (by weight) in Sweden The prevalence of manufactured cigarette smoking is relatively low in Sweden compared to the rest of the EU Mortality from smoking related diseases, including oral cancer, is generally low in Sweden compared to US and UK 3
Is snus a safe, or safer, alternative to smoking? 4
SNUS ISSUES TO BE DISCUSSED Cancer Non-neoplastic oral disease Circulatory disease risk Circulatory disease risk factors (e.g. BMI, blood pressure, diabetes) Other health endpoints Joint relationship of snus and smoking Does snus encourage initiation of smoking? Does snus discourage cessation of smoking? 5
CANCER RISK Ever vs never snus users Cancer site Whole population (adjusted for smoking) Never smokers n RR 95% CI n RR 95% CI Oropharynx 7 0.97 0.68-1.37 4 1.01 0.71-1.45 Stomach 5 0.98 0.82-1.17 2 0.90 0.35-2.30 Oesophagus 4 1.10 0.92-1.33 1 1.92 1.00-3.68 Lung 2 0.71 0.66-0.76 2 0.82 0.52-1.28 Pancreas 2 1.20 0.66-2.20 2 1.61 0.77-3.34 Any cancer 2 1.03 0.91-1.16 2 1.10 0.94-1.29 n = no of studies combined RR = relative risk CI = confidence interval 6
Study PANCREATIC CANCER RISK Ever vs never snus users Whole population (adjusted for smoking) Never smokers N RR 95% CI N RR 95% CI Norway Cohorts (Boffetta et al 2005) Construction Workers (Luo et al 2007) 45 1.67 1.12-2.50 3 0.85 0.24-3.07 NA 0.90 0.70-1.20 20 2.00 1.20-3.30 Combined 1.20 0.66-2.20 1.61 0.77-3.34 N = no of cancers in snus users RR =Relative risk CI = confidence interval 7
NON-NEOPLASTIC ORAL DISEASE All users of snus have a snuff-dipper s lesion (discolouration and thickening of oral mucosa) where the snus is placed The severity of the lesion relates to the time and amount used per day Quitting snus rapidly reduces severity and then eliminates the lesion There is no evidence that oral cancers occur at the site of the lesion There is no clear relationship of snus use to periodontal or gingival disease A relationship of snus use with tooth loss and dental caries is not established 8
CIRCULATORY DISEASE RISK Ever vs never snus users Disease Ischaemic heart disease/ acute myocardial infarction Whole population (adjusted for smoking) Never smokers n RR 95% CI n RR 95% CI 9 1.01 0.91-1.12 9 0.99 0.85-1.14 Stroke 6 1.05 0.95-1.15 6 1.06 0.96-1.17 Any circulatory disease 5 1.08 0.92-1.27 5 1.08 0.87-1.33 n = no of studies combined RR = relative risk CI = confidence interval 9
CIRCULATORY DISEASE RISK FACTORS DIABETES BLOOD PRESSURE One study (Persson et al, 2000) shows increased prevalence in users but five other studies do not There is no consistent association with glucose intolerance, fasting glucose levels, fasting insulin levels or metabolic syndrome Cross over studies show an acute effect of snus Cross-sectional studies generally do not show an effect (except for Construction Workers Study) BODY MASS INDEX Consistent reports of higher BMI in snus users OTHER - no effect Atherosclerosis, exercise response, cholesterol, fibrinogen, platelets, vitamin and antioxidant levels - possible effect Raynaud-type symptoms (two studies), endothelial function (one), triglycerides (two of five studies) 10
OTHER HEALTH ENDPOINTS Disease Comment Studies Respiratory mortality Increase in men aged 80+, no increase in younger men Peptic ulcer No association 1 Gallstone disease No association 1 IBD Increase (in ever smokers) for Crohn s disease and, surprisingly, ulcerative colitis Birthweight Reduced in snus users by 39g (6-72g) 1 Preeclampsia Increased in snus users (reduced in smokers) 1 Reproductive parameters No association 1 Schizophrenia Snus use relatively common in schizophrenics 1 Neurodegenerative disorders No increased risk of multiple or amyotrophic lateral sclerosis Back pain Some evidence of an association but causal? 4 11 1 1 2
Joint relationship of snus and smoking Association Age group Studies Typical odds ratio Current snus use/ current smoking Adolescents 8 6 Adults 8 1 Ever snus use/ ever smoking Adolescents 3 >10 Adults 6 2.5 12
Does snus encourage initiation of smoking? Prospective studies of never (or non) smokers at start Snus users at the study start have higher risk of being smokers at the end of follow-up RR 1.5-2.0 Could be due to confounding by risk taking Retrospective studies Other evidence US studies have suggested that confounding is important Two studies suggest that initiation is less in snus users Statistical methods biased (similarly in both studies) Relatively few smokers use snus prior to starting to smoke 13
Bias in the analysis of Ramström and Foulds N % If 20% smoke, 10% snus - no association (%) 1 Never smoking or snus 1397 44.7 72 2 Snus only 402 12.9 8 3 Smoking only 888 28.4 18 4 Both, snus first 100 3.2 0.67 5 Both, smoking first 338 10.8 1.33 Total 3125 100.0 100.0 Smoking among snus starters 100/502 = 20% 7.7% Smoking among others 1226/2623 = 47% 21.2% Odds ratio 0.28 0.33 14
Does snus use discourage cessation of smoking? Data from six prospective studies consistently show that cessation is slightly more likely in smokers using snus at baseline RR about 1.5 The studies are virtually unadjusted for confounding variables Data from four retrospective studies all suggest that snus users are more likely to quit smoking These analyses are all biased as the time available to quit is not matched However, no published data suggests that snus use discourages quitting 15
CONCLUSIONS There is little or no effect on cancer or circulatory disease Adverse effects claimed are not as yet confirmed It is clear that snus is vastly safer than smoking cigarettes It is unclear whether the use of snus increases initiation of smoking anyway the great majority of smokers did not use snus prior to starting to smoke There is no evidence that snus use discourages quitting indeed it may aid quitting If one must take nicotine, snus is a much better way than smoking to do so 16
SNUS AS A VIRTUALLY SAFE ALTERNATIVE TO SMOKING: A REVIEW OF THE EVIDENCE Peter Lee and Jan Hamling P. N. Lee Statistics & Computing Ltd PeterLee@pnlee.co.uk 27 th April 2010 Snus and health_2.ppt 17