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. 2016 Oct 13;10(10):CD005231.
doi: 10.1002/14651858.CD005231.pub3.

Interventions to reduce harm from continued tobacco use

Nicola Lindson-Hawley  1 , Jamie Hartmann-Boyce, Thomas R Fanshawe, Rachna Begh, Amanda Farley, Tim Lancaster
Affiliations

Interventions to reduce harm from continued tobacco use

Nicola Lindson-Hawley et al. Cochrane Database Syst Rev. .

Abstract

Background: Although smoking cessation is currently the only guaranteed way to reduce the harm caused by tobacco smoking, a reasonable secondary tobacco control approach may be to try and reduce the harm from continued tobacco use amongst smokers unable or unwilling to quit. Possible approaches to reduce the exposure to toxins from smoking include reducing the amount of tobacco used, and using less toxic products, such as pharmaceutical, nicotine and potential reduced-exposure tobacco products (PREPs), as an alternative to cigarettes.

Objectives: To assess the effects of interventions intended to reduce the harm to health of continued tobacco use, we considered the following specific questions: do interventions intended to reduce harm have an effect on long-term health status?; do they lead to a reduction in the number of cigarettes smoked?; do they have an effect on smoking abstinence?; do they have an effect on biomarkers of tobacco exposure?; and do they have an effect on biomarkers of damage caused by tobacco?

Search methods: We searched the Cochrane Tobacco Addiction Group Trials Register (CRS) on the 21st October 2015, using free-text and MeSH terms for harm reduction, smoking reduction and cigarette reduction.

Selection criteria: Randomized or quasi-randomized controlled trials of interventions to reduce the amount smoked, or to reduce harm from smoking by means other than cessation. We include studies carried out in smokers with no immediate desire to quit all tobacco use. Primary outcomes were change in cigarette consumption, smoking cessation and any markers of damage or benefit to health, measured at least six months from the start of the intervention.

Data collection and analysis: We assessed study eligibility for inclusion using standard Cochrane methods. We pooled trials with similar interventions and outcomes (> 50% reduction in cigarettes a day (CPD) and long-term smoking abstinence), using fixed-effect models. Where it was not possible to meta-analyse data, we summarized findings narratively.

Main results: Twenty-four trials evaluated interventions to help those who smoke to cut down the amount smoked or to replace their regular cigarettes with PREPs, compared to placebo, brief intervention, or a comparison intervention. None of these trials directly tested whether harm reduction strategies reduced the harms to health caused by smoking. Most trials (14/24) tested nicotine replacement therapy (NRT) as an intervention to assist reduction. In a pooled analysis of eight trials, NRT significantly increased the likelihood of reducing CPD by at least 50% for people using nicotine gum or inhaler or a choice of product compared to placebo (risk ratio (RR) 1.75, 95% confidence interval (CI) 1.44 to 2.13; 3081 participants). Where average changes from baseline were compared for different measures, carbon monoxide (CO) and cotinine generally showed smaller reductions than CPD. Use of NRT versus placebo also significantly increased the likelihood of ultimately quitting smoking (RR 1.87, 95% CI 1.43 to 2.44; 8 trials, 3081 participants; quality of the evidence: low). Two trials comparing NRT and behavioural support to brief advice found a significant effect on reduction, but no significant effect on cessation. We found one trial investigating each of the following harm reduction intervention aids: bupropion, varenicline, electronic cigarettes, snus, plus another of nicotine patches to facilitate temporary abstinence. The evidence for all five intervention types was therefore imprecise, and it is unclear whether or not these aids increase the likelihood of smoking reduction or cessation. Two trials investigating two different types of behavioural advice and instructions on reducing CPD also provided imprecise evidence. Therefore, the evidence base for this comparison is inadequate to support the use of these types of behavioural advice to reduce smoking. Four studies of PREPs (cigarettes with reduced levels of tar, carbon and nicotine, and in one case delivered using an electronically-heated cigarette smoking system) showed some reduction in exposure to some toxicants, but it is unclear whether this would substantially alter the risk of harm. We judged the included studies to be generally at a low or unclear risk of bias; however, there were some ratings of high risk, due to a lack of blinding and the potential for detection bias. Using the GRADE system, we rated the overall quality of the evidence for our cessation outcomes as 'low' or 'very low', due to imprecision and indirectness. A 'low' grade means that further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. A 'very low' grade means we are very uncertain about the estimate.

Authors' conclusions: People who do not wish to quit can be helped to cut down the number of cigarettes they smoke and to quit smoking in the long term, using NRT, despite original intentions not to do so. However, we rated the evidence contributing to the cessation outcome for NRT as 'low' by GRADE standards. There is a lack of evidence to support the use of other harm reduction aids to reduce the harm caused by continued tobacco smoking. This could simply be due to the lack of high-quality studies (our confidence in cessation outcomes for these aids is rated 'low' or 'very low' due to imprecision by GRADE standards), meaning that we may have missed a worthwhile effect, or due to a lack of effect on reduction or quit rates. It is therefore important that more high-quality RCTs are conducted, and that these also measure the long-term health effects of treatments.

PubMed Disclaimer

Conflict of interest statement

AF has received personal consultancy fees from the Annals of Internal Medicine to write an independent review of a commissioned article.

JHB has no known conflicts of interest.

NLH is a co‐applicant on a completed trial investigating nicotine patch preloading for smoking cessation (not a harm reduction approach). The nicotine patches were provided free of charge by GlaxoSmithKline; however the trial was funded by the NIHR HTA (09/110/01), and the running and the reporting of the trial were carried out independently to the funder and treatment provider.

RB has no known conflicts of interest.

TL has no known conflicts of interest.

TRF has no known conflicts of interest.

Figures

1
1
Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
2
2
Forest plot of comparison: 1 Nicotine replacement therapy to assist smoking reduction versus placebo, outcome: 1.1 Reduction in cigarettes/day of > 50% of baseline or cessation.
3
3
Forest plot of comparison: 1 Nicotine replacement therapy to assist smoking reduction versus placebo, outcome: 1.2 Cessation at long‐term follow‐up (subgroups by type of NRT).
1.1
1.1. Analysis
Comparison 1 Nicotine replacement therapy to assist smoking reduction versus placebo, Outcome 1 Reduction in cigarettes/day of > 50% of baseline or cessation.
1.2
1.2. Analysis
Comparison 1 Nicotine replacement therapy to assist smoking reduction versus placebo, Outcome 2 Cessation at long‐term follow‐up (subgroups by type of NRT).
2.1
2.1. Analysis
Comparison 2 NRT combined with counselling to assist smoking reduction versus brief cessation advice, Outcome 1 Reduction in cigarettes/day of > 50% of baseline or cessation.
2.2
2.2. Analysis
Comparison 2 NRT combined with counselling to assist smoking reduction versus brief cessation advice, Outcome 2 Cessation at long‐term follow‐up.
3.1
3.1. Analysis
Comparison 3 Nicotine patches versus placebo for temporary abstinence, Outcome 1 Cessation at long‐term follow‐up.
4.1
4.1. Analysis
Comparison 4 Bupropion to assist smoking reduction versus placebo, Outcome 1 Outcomes at long‐term follow‐up.
5.1
5.1. Analysis
Comparison 5 Varenicline to assist smoking reduction versus placebo, Outcome 1 Outcomes at long‐term follow‐up.
6.1
6.1. Analysis
Comparison 6 Ecigarettes to assist smoking reduction versus placebo, Outcome 1 Outcomes at long‐term follow‐up.
7.1
7.1. Analysis
Comparison 7 Snus to reduce and replace smoking versus placebo, Outcome 1 Outcomes at long‐term follow‐up.
8.2
8.2. Analysis
Comparison 8 PREPs to assist smoking reduction versus smoking as usual, Outcome 2 Cessation at long‐term follow‐up.
9.1
9.1. Analysis
Comparison 9 Computerized programme to assist smoking reduction versus self‐help reduction guide, Outcome 1 Outcomes at long‐term follow‐up.
10.1
10.1. Analysis
Comparison 10 Behavioural reduction advice to assist smoking reduction versus health mailings, Outcome 1 Outcomes at long‐term follow‐up.
See this image and copyright information in PMC

Update of

References

References to studies included in this review

Australia NNCG‐017 {unpublished data only}
    1. Pfizer Inc. Summary of Clinical Efficacy. Application for licensing of Nicorette Inhalator/Gum for smoking reduction leading to cessation. Company data NICORE‐1013‐273‐SU.
Batra 2005 {published and unpublished data}
    1. Batra A, Klingler K, Landfeldt B, Friederich HM, Westin A, Danielsson T. Smoking reduction treatment with 4‐mg nicotine gum: A double‐blind, randomized, placebo‐controlled study. Clinical Pharmacology & Therapeutics 2005;78(6):689‐96. - PubMed
    1. Landfeldt B, Batra A, Friederich HM, Klingler K, Westin A. Smoking reduction with a 4 mg nicotine gum ‐ final results from a placebo‐controlled trial over 13 months. Society for Research on Nicotine and Tobacco 5th European Meeting November 20‐22 2003 Padua: Abstract book. 2003.
Benowitz 2012 {published data only}
    1. Benowitz NL, Dains KM, Hall SM, Stewart S, Wilson M, Dempsey D, et al. Smoking behavior and exposure to tobacco toxicants during 6 months of smoking progressively reduced nicotine content cigarettes. Cancer Epidemiology, Biomarkers & Prevention 2012;21(5):761‐9. - PMC - PubMed
Bolliger 2000 {published data only}
    1. Bolliger CT. Practical experiences in smoking reduction and cessation. Addiction 2000;95(1 Suppl 1):S19‐S24. - PubMed
    1. Bolliger CT, Zellweger JP, Danielsson T, Biljon X, Robidou A, Westin A, et al. Influence of long‐term smoking reduction on health risk markers and quality of life. Nicotine & Tobacco Research 2002;4(4):433‐9. - PubMed
    1. Bolliger CT, Zellweger JP, Danielsson T, Biljon X, Robidou A, Westin A, et al. Smoking reduction with oral nicotine inhalers: double blind, randomised clinical trial of efficacy and safety. BMJ 2000;321(7257):329‐33. - PMC - PubMed
Caponnetto 2013 {published data only}
    1. Caponnetto P, Campagna D, Cibella F, Morjaria JB, Caruso M, Russo C, et al. EffiCiency and safety of an eLectronic cigAreTte (ECLAT) as tobacco cigarettes substitute: a prospective 12‐month randomized control design study. PLoS ONE 2013;8(6):e66317. - PMC - PubMed
Carpenter 2003 {published data only}
    1. Carpenter MJ, Hughes JR, Keely JP. Effect of smoking reduction on later cessation: a pilot experimental study. Nicotine & Tobacco Research 2003;5(2):155‐62. - PubMed
Carpenter 2004 {published data only}
    1. Carpenter MJ, Hughes JR, Solomon LJ, Callas PW. Both smoking reduction with nicotine replacement therapy and motivational advice increase future cessation among smokers unmotivated to quit. Journal of Consulting and Clinical Psychology 2004;72(3):371‐81. - PubMed
Chan 2011 {published data only}
    1. Chan SCC, Leung DYP, Abdullah ASM, Wong VT, Hedley AJ, Lam TH. A randomized controlled trial of a smoking reduction plus nicotine replacement therapy intervention for smokers not willing to quit smoking. Addiction 2011;106(6):1155‐63. - PubMed
Etter 2004 {published data only}
    1. Dar R, Stronguin F, Etter JF. Assigned versus perceived placebo effects in nicotine replacement therapy for smoking reduction in Swiss smokers. Journal of Consulting and Clinical Psychology 2005;73(2):350‐3. - PubMed
    1. Etter JF, Laszlo E. Postintervention effect of nicotine replacement therapy for smoking reduction: a randomized trial with a 5‐year follow‐up. Journal of Clinical Psychopharmacology 2007;27(2):151‐5. - PubMed
    1. Etter JF, Laszlo E, Perneger TV. Postintervention effect of nicotine replacement therapy on smoking reduction in smokers who are unwilling to quit: Randomized trial. Journal of Clinical Psychopharmacology 2004;24(2):174‐9. - PubMed
    1. Etter JF, Laszlo E, Zellweger JP, Perrot C, Perneger TV. Nicotine replacement to reduce cigarette consumption in smokers who are unwilling to quit: a randomized trial. Journal of Clinical Psychopharmacology 2002;22(5):487‐95. - PubMed
Glasgow 2009 {published data only}
    1. Glasgow RE, Gaglio B, Estabrooks PA, Marcus AC, Ritzwoller DP, Smith TL, et al. Long‐term results of a smoking reduction program. Medical Care 2009;47(1):115‐20. - PubMed
Hanson 2008 {published data only}
    1. Hanson K, Zylla E, Allen S, Avery G. Harm reduction: an intervention for adolescent smokers (SYM3B). Society for Research on Nicotine and Tobacco 12th Annual Meeting February 15‐18, Orlando, Florida. 2006.
    1. Hanson K, Zylla E, Allen S, Li Z, Hatsukami DK. Cigarette reduction: an intervention for adolescent smokers. Drug and Alcohol Dependence 2008;95(1‐2):164‐8. - PMC - PubMed
Hatsukami 2004a {published and unpublished data}
    1. Hatsukami DK, Rennard S, Patel MK, Kotlyar M, Malcolm R, Nides MA, et al. Effects of sustained‐release bupropion among persons interested in reducing but not quitting smoking. American Journal of Medicine 2004;116(3):151‐7. - PubMed
    1. Rennard S, Hatsukami D, Malcolm RE, Patel MK, Jamerson BD, Dozier G. Zyban (bupropion HCL SR) vs placebo as an aid to smoking reduction among smokers unwilling and unable to quit smoking (PO4 77). Society for Research on Nicotine and Tobacco 7th Annual Meeting March 23‐23 Seattle, Washington. 2001:117.
Haustein 2003 {published data only}
    1. Haustein KO, Batra A. A double‐blind, randomized, placebo‐controlled multicenter trial of a nicotine chewing gum in smoking reduction. Study report for study 980‐CHC‐9021‐0013 2002.
    1. Haustein KO, Batra A, Landfeldt B, Westin A. The effect of short‐term or long‐term reduction on smoking cessation; results from a placebo controlled smoking reduction study with the nicotine gum. Nicotine & Tobacco Research 2003;5:278.
    1. Haustein KO, Krause J, Haustein H, Rasmussen T, Cort N. Changes in hemorheological and biochemical parameters following short‐term and long‐term smoking cessation induced by nicotine replacement therapy (NRT). International Journal Of Clinical Pharmacology And Therapeutics 2004;42(2):83‐92. - PubMed
    1. Pfizer Inc. Summary of Clinical Efficacy. Application for licensing of Nicorette Inhalator/Gum for smoking reduction leading to cessation. Company data NICORE‐1013‐273‐SU.
Hughes 2011 {published data only}
    1. Hughes JR, Rennard SI, Fingar JR, Talbot SK, Callas PW, Fagerström KO. Efficacy of varenicline to prompt quit attempts in smokers not currently trying to quit: a randomized placebo‐controlled trial. Nicotine & Tobacco Research 2011;13(10):955–64. - PMC - PubMed
Joksić 2011 {published data only}
    1. Joksić G, Spasojević‐Tišma V, Antić R, Nilsson R, Rutqvist LE. Randomized, placebo‐controlled, double‐blind trial of Swedish snus for smoking reduction and cessation. Harm Reduction Journal 2011;8:25. - PMC - PubMed
Joseph 2008 {published data only}
    1. Joseph A, Hecht S, Murphy S, Gross M, Lando H, Bliss R, et al. A randomized controlled trial of smoking reduction in heart disease patients. Nicotine & Tobacco Research 2005;7(4):697.
    1. Joseph AM, Bliss RL, Zhao F, Lando H. Predictors of smoking reduction without formal intervention. Nicotine & Tobacco Research 2005;7(2):277‐82. - PubMed
    1. Joseph AM, Hecht SS, Murphy SE, Lando H, Carmella SG, Gross M, et al. Smoking reduction fails to improve clinical and biological markers of cardiac disease: a randomized controlled trial. Nicotine & Tobacco Research 2008;10(3):471‐81. - PMC - PubMed
Kralikova 2009 {published data only (unpublished sought but not used)}
    1. Kralikova E, Kozak J, Rasmussen T, Cort N. The clinical benefits of NRT‐supported smoking reduction. Nicotine & Tobacco Research 2002;4(2):243.
    1. Kralikova E, Kozak JT, Rasmussen T, Gustavsson G, Houezec J. Smoking cessation or reduction with nicotine replacement therapy: a placebo‐controlled double blind trial with nicotine gum and inhaler. BMC Public Health 2009;9:433. [DOI: 10.1186/1471-2458/9/433] - DOI - PMC - PubMed
Mendes 2008 {published data only}
    1. Mendes P, Kapur S, Wang J, Feng S, Roethig H. A randomized, controlled exposure study in adult smokers of full flavor Marlboro cigarettes switching to Marlboro Lights or Marlboro Ultra Lights cigarettes. Regulatory Toxicology & Pharmacology 2008;51(3):295‐305. - PubMed
Nackaerts 2009 {published data only}
    1. Nackaerts K, Salhi B, Devolder A, Meysman M, Boudrez H, Dyck L, et al. A randomized, double‐blind, placebo‐controlled phase 3 study investigating the efficacy of nicotine substitution (NS) on nicotine withdrawal symptoms (NWS) in hospitalised smokers (HS). ERS Vienna 2009 Congress. 2009.
Rennard 2006 {published and unpublished data}
    1. Rennard SI, Glover E, Leischow S, Daughton DM, Glover P, Muramoto M. Efficacy of nicotine inhaler in smoking reduction. Nicotine & Tobacco Research 2002;4(3):380. - PubMed
    1. Rennard SI, Glover ED, Leischow S, Daughton DM, Glover PN, Muramoto M, et al. Efficacy of the nicotine inhaler in smoking reduction: A double‐blind, randomized trial. Nicotine & Tobacco Research 2006;8(4):555‐64. - PubMed
Riley 2002 {published data only}
    1. Riley W, Jerome A, Behar A, Weil J. Computer and manual self‐help behavioral strategies for smoking reduction: Initial feasibility and one‐year follow‐up. Nicotine & Tobacco Research 2002;4(Suppl 2):S183‐S188. - PubMed
Roethig 2008 {published data only}
    1. Roethig HJ, Feng S, Liang Q, Liu J, Rees WA, Zedler BK. A 12‐month, randomized, controlled study to evaluate exposure and cardiovascular risk factors in adult smokers switching from conventional cigarettes to a second‐generation electrically heated cigarette smoking system. Journal of Clinical Pharmacology 2008;48(5):580‐91. - PubMed
    1. Roethig HJ, Kinser RD, Lau RW, Walk RA, Wang N. Short‐term exposure evaluation of adult smokers switching from conventional to first‐generation electrically heated cigarettes during controlled smoking. Journal of Clinical Pharmacology 2005;45(2):133‐45. - PubMed
    1. Roethig HJ, Zedler BK, Kinser RD, Feng S, Nelson BL, Liang Q. Short‐term clinical exposure evaluation of a second‐generation electrically heated cigarette smoking system. Journal of Clinical Pharmacology 2007;47(4):518‐30. - PubMed
Sarkar 2008 {published data only}
    1. Sarkar M, Kapur S, Frost‐Pineda K, Feng S, Wang J, Liang Q, et al. Evaluation of biomarkers of exposure to selected cigarette smoke constituents in adult smokers switched to carbon‐filtered cigarettes in short‐term and long‐term clinical studies. Nicotine & Tobacco Research 2008;10(12):1761‐72. - PubMed
Wennike 2003 {published data only}
    1. Wennike P, Danielsson T, Landfeldt B, Westin A, Tønnesen P. Smoking reduction promotes smoking cessation: results from a double blind, randomized, placebo‐controlled trial of nicotine gum with 2‐year follow‐up. Addiction 2003;98(10):1395‐402. - PubMed

References to studies excluded from this review

Adriaens 2014 {published data only}
    1. Adriaens K, Gucht D, Declerck P, Baeyens F. Effectiveness of the electronic cigarette: An eight‐week Flemish study with six‐month follow‐up on smoking reduction, craving and experienced benefits and complaints. International Journal of Environmental Research and Public Health 2014;11(11):11220‐48. - PMC - PubMed
Applegate 2004 {published data only}
    1. Applegate BW, Riley WT, Sowell A. A comparison of computer‐assisted scheduled gradual reduction vs. self help in unmotivated smokers (POS1‐028). Society for Research on Nicotine and Tobacco 10th Annual Meeting February 18‐21, Phoenix, Arizona. 2004.
Baker 2006 {published data only}
    1. Baker A, Richmond R, Haile M, Lewin TJ, Carr VJ, Taylor RL, et al. A randomized controlled trial of a smoking cessation intervention among people with a psychotic disorder. American Journal of Psychiatry 2006;163(11):1934‐42. - PubMed
Barrett 2011 {published data only}
    1. Barrett SP, Wagner E. A comparison between quick‐release nicotine lozenges and Swedish‐style snus for the acute management of craving. Tobacco control 2011;20:386. - PubMed
Benowitz 2005 {published data only}
    1. Benowitz NL, Jacob P, Bernert JT, Wilson M, Wang LG, Allen F, et al. Carcinogen exposure during short‐term switching from regular to "Light" cigarettes. Cancer Epidemiology, Biomarkers & Prevention 2005;14(6):1376‐83. - PubMed
Bloch 2010 {published data only}
    1. Bloch B, Reshef A, Cohen T, Tafla A, Gathas S, Israel S, et al. Preliminary effects of bupropion and the promoter region (HTTLPR) serotonin transporter (SLC6A4) polymorphism on smoking behavior in schizophrenia. Psychiatry Research 2010;175(1‐2):38‐42. - PubMed
Borland 1999 {published data only}
    1. Borland R, Owen N, Tooley G, Treijs I, Roberts L, Hill D. Promoting reduced smoking rates in the context of workplace smoking bans. American Journal of Health Promotion 1999;14(1):1‐3, ii. - PubMed
Breland 2006 {published data only}
    1. Breland AB, Kleykamp BA, Eissenberg T. Clinical laboratory evaluation of potential reduced exposure products for smokers. Nicotine & Tobacco Research 2006;8(6):727‐38. - PubMed
Caldwell 2010 {published data only}
    1. Caldwell B, Burgess C, Crane J. Randomized crossover trial of the acceptability of snus, nicotine gum, and Zonnic therapy for smoking reduction in heavy smokers. Nicotine & Tobacco Research 2010;12(2):179‐83. - PubMed
Chiou 2013 {published data only}
    1. Chiou WB, Wu WH, Chang MH. Think abstractly, smoke less: a brief construal‐level intervention can promote self‐control, leading to reduced cigarette consumption among current smokers. Addiction 2013;108(5):985‐92. - PubMed
Chisolm 2013 {published data only}
    1. Chisolm MS, Fitzsimons H, Leoutsakos J‐MS, Acquavita SP, Heil SH, Wilson‐Murphy M, et al. A comparison of cigarette smoking profiles in opioid‐dependent pregnant patients receiving methadone or buprenorphine. Nicotine & Tobacco Research 2013;15:1297‐304. - PMC - PubMed
Cunningham 2006 {published data only}
    1. Cunningham JA, Faulkner G, Selby P, Cordingley J. Motivating smoking reductions by framing health information as safer smoking tips. Addictive Behaviors 2006;31(8):1465‐8. - PubMed
Dautzenberg 2001 {published data only}
    1. Dautzenberg B, Ruff F, Vaucher M, Maillon P, Jacob N, Kienzler JL, et al. First demonstration of the good efficacy/safety ratio of Nicotinell® 1mg Lozenge (NL 1mg), a new form of nicotine substitution, by randomised clinical trial. European Respiratory Journal. 2001; Vol. 18.
Ebbert 2015 {published data only}
    1. Ebbert JO, Hughes JR, West RJ, Rennard SI, Russ C, McRae TD, et al. Effect of varenicline on smoking cessation through smoking reduction. A randomized clinical trial. JAMA 2015;313(7):687‐94. - PMC - PubMed
    1. NCT01370356. A study to evaluate the efficacy and safety of varenicline compared to placebo for smoking cessation through reduction [NCT01370356] [A phase 4, multi‐national, randomized, double‐blind, placebo‐controlled study to evaluate the efficacy and safety of varenicline compared to placebo for smoking cessation through reduction]. clinicaltrials.gov/ct2/show/NCT01370356 (first received 8th June 2011).
Eliasson 2001 {published data only}
    1. Eliasson B, Hjalmarson A, Kruse E, Landfeldt B, Westin A. Effect of smoking reduction and cessation on cardiovascular risk factors. Nicotine & Tobacco Research 2001;3(3):249‐55. - PubMed
Etter 2003 {published data only}
    1. Etter JF, Houezec J, Landfeldt B. Impact of messages on concomitant use of nicotine replacement therapy and cigarettes: a randomized trial on the Internet. Addiction 2003;98(7):941‐950. - PubMed
Fagerström 1997 {published data only}
    1. Fagerström KO, Tejding R, Westin A, Lunell E. Aiding reduction of smoking with nicotine replacement medications: hope for the recalcitrant smoker?. Tobacco Control 1997;6(4):311‐6. - PMC - PubMed
Fagerström 2000 {published data only}
    1. Fagerström KO, Hughes JR, Rasmussen T, Callas PW. Randomised trial investigating effect of a novel nicotine delivery device (Eclipse) and a nicotine oral inhaler on smoking behaviour, nicotine and carbon monoxide exposure, and motivation to quit. Tobacco Control 2000;9:327‐33. - PMC - PubMed
Fagerström 2002b {published data only}
    1. Fagerström KO, Hughes JR, Callas PW. Long‐term effects of the Eclipse cigarette substitute and the nicotine inhaler in smokers not interested in quitting. Nicotine & Tobacco Research 2002;4(Suppl 2):S141‐S145. - PubMed
Fatemi 2005 {published data only}
    1. Fatemi SH, Stary JM, Hatsukami DK, Murphy SE. A double‐blind placebo‐controlled cross over trial of bupropion in smoking reduction in schizophrenia. Schizophrenia Research 2005;76(2‐3):353‐6. - PubMed
Fatemi 2013 {published data only}
    1. Fatemi SH, Yousefi MK, Kneeland RE, Liesch SB, Folsom TD, Thuras PD. Antismoking and potential antipsychotic effects of varenicline in subjects with schizophrenia or schizoaffective disorder: a double‐blind placebo and bupropion‐controlled study. Schizophrenia Research 2013;146(1‐3):376‐8. - PubMed
Feng 2006 {published data only}
    1. Feng S, Roethig HJ, Liang Q, Kinser R, Jin Y, Scherer G, et al. Evaluation of urinary 1‐hydroxypyrene, S‐phenylmercapturic acid, trans,trans‐muconic acid, 3‐methyladenine, 3‐ethyladenine, 8‐hydroxy‐2'‐deoxyguanosine and thioethers as biomarkers of exposure to cigarette smoke. Biomarkers 2006;11(1):28‐52. - PubMed
Frost 1995 {published data only}
    1. Frost C, Fullerton FM, Stephen AM, Stone R, Nicolaides‐Bouman A, Densem J, et al. The tar reduction study: randomised trial of the effect of cigarette tar yield reduction on compensatory smoking. Thorax 1995;50(10):1038‐43. - PMC - PubMed
Frost‐Pineda 2008 {published data only}
    1. Frost‐Pineda K, Zedler BK, Liang Q, Roethig HJ. Environmental tobacco smoke (ETS) evaluation of a third‐generation electrically heated cigarette smoking system (EHCSS). Regulatory Toxicology and Pharmacology 2008;52(2):118‐21. - PubMed
    1. Frost‐Pineda K, Zedler BK, Oliveri D, Feng S, Liang Q, Roethig HJ. Short‐term clinical exposure evaluation of a third‐generation electrically heated cigarette smoking system (EHCSS) in adult smokers. Regulatory Toxicology and Pharmacology 2008;52(2):104‐10. - PubMed
    1. Frost‐Pineda K, Zedler BK, Oliveri D, Liang Q, Feng S, Roethig HJ. 12‐Week clinical exposure evaluation of a third‐generation electrically heated cigarette smoking system (EHCSS) in adult smokers. Regulatory Toxicology and Pharmacology 2008;52(2):111‐7. - PubMed
    1. Munjal S, Koval T, Muhammad R, Jin Y, Demmel V, Roethig HJ, et al. Heart rate variability increases with reductions in cigarette smoke exposure after 3 days. Journal of Cardiovascular Pharmacology & Therapeutics 2009;14(3):192‐8. - PubMed
    1. Unverdorben M, Bijl A, Potgieter L, Liang Q, Meyer BH, Roethig HJ. Effects of levels of cigarette smoke exposure on symptom‐limited spiroergometry. Preventive Cardiology 2007;10(2):83‐91. - PubMed
Gelkopf 2012 {published data only}
    1. Gelkopf M, Noam S, Rudinski D, Lerner A, Behrbalk P, Bleich A, et al. Nonmedication smoking reduction program for inpatients with chronic schizophrenia: a randomized control design study. Journal of Nervous and Mental Disease 2012;200(2):142‐6. - PubMed
Glasgow 1983 {published data only}
    1. Glasgow RE, Klesges R, Godding P, Gegelman R. Controlled smoking with or without carbon monoxide feedback, as an alternative for chronic smokers. Behavior Therapy 1983;14(3):386‐97.
    1. Glasgow RE, Klesges RC, Vasey MW. Controlled smoking for chronic smokers: an extension and replication. Addictive Behaviors 1983;8(2):143‐50. - PubMed
Gray 2008 {published data only}
    1. Gray JN, Breland AB, Weaver M, Eissenberg T. Potential reduced exposure products (PREPs) for smokeless tobacco users: clinical evaluation methodology. Nicotine & Tobacco Research 2008;10(9):1441‐8. - PMC - PubMed
Hagen 2011 {published data only}
    1. Hagen EH, Roulette C, Remiker M, Wilcox J, Hewlett BS, Sullivan RJ, et al. Does treating intestinal helminth infections reduce smoking behavior? Results of a double‐blind, placebo‐controlled, randomized control trial among Central African foragers. American Journal of Physical Anthropology. 2011:153.
Hatsukami 2004b {published data only}
    1. Hatsukami DK, Lemmonds C, Zhang Y, Murphy SE, Le C, Carmella SG, et al. Evaluation of carcinogen exposure in people who used "reduced exposure" tobacco products. Journal of the National Cancer Institute 2004;96(11):844‐52. - PubMed
Hatsukami 2005 {published data only}
    1. Hatsukami DK, Kotlyar M, Allen S, Jensen J, Li S, Le C, et al. Effects of cigarette reduction on cardiovascular risk factors and subjective measures. Chest 2005;128(4):2528‐37. - PubMed
    1. Hecht SS, Carmella SG, Le KA, Murphy SE, Li YS, Le C, et al. Effects of reduced cigarette smoking on levels of 1‐hydroxypyrene in urine. Cancer Epidemiology, Biomarkers & Prevention 2004;13(5):834‐42. - PubMed
    1. Hecht SS, Murphy SE, Carmella SG, Zimmerman CL, Losey L, Kramarczuk I, et al. Effects of reduced cigarette smoking on the uptake of a tobacco‐specific lung carcinogen. Journal of the National Cancer Institute 2004;96(2):107‐15. - PubMed
    1. Kotlyar M, Jensen J, Li S, Hatsukami DK. Effect of smoking reduction on cardiovascular biomarkers and subjective measures. Nicotine & Tobacco Research 2004;6(4):719.
    1. Murphy SE, Link CA, Jensen J, Le C, Puumala SS, Hecht SS, et al. A comparison of urinary biomarkers of tobacco and carcinogen exposure in smokers. Cancer Epidemiology, Biomarkers & Prevention 2004;13(10):1617‐23. - PubMed
Hatsukami 2007b {published data only}
    1. Hatsukami DK, Ebbert JO, Anderson A, Lin H, Le C, Hecht SS. Smokeless tobacco brand switching: a means to reduce toxicant exposure?. Drug & Alcohol Dependence 2007;87(2‐3):217‐24. - PMC - PubMed
Hatsukami 2008 {published data only}
    1. Hatsukami DK, Ebbert JO, Edmonds A, Li C, Lin H, Le C, et al. Smokeless tobacco reduction: preliminary study of tobacco‐free snuff versus no snuff. Nicotine & Tobacco Research 2008;10(1):77‐85. - PMC - PubMed
Hatsukami 2010 {published data only}
    1. Hatsukami DK, Kotlyar M, Hertsgaard LA, Zhang Y, Carmella SG, Jensen JA, et al. Reduced nicotine content cigarettes: effects on toxicant exposure, dependence and cessation. Addiction 2010;105(2):343‐55. - PMC - PubMed
Hatsukami 2016 {published data only}
    1. Hatsukami DK, Severson H, Anderson A, Vogel RI, Jensen J, Broadbent B, et al. Randomised clinical trial of snus versus medicinal nicotine among smokers interested in product switching. Tobacco Control 2016;25(3):267‐74. - PMC - PubMed
Hughes 2004 {published data only}
    1. Hughes JR, Hecht SS, Carmella SG, Murphy SE, Callas P. Smoking behaviour and toxin exposure during six weeks use of a potential reduced exposure product: Omni. Tobacco Control 2004;13(2):175‐9. - PMC - PubMed
Hurt 2000 {published data only}
    1. Hurt RD, Croghan GA, Wolter TD, Croghan IT, Offord KP, Williams GM, et al. Does smoking reduction result in reduction of biomarkers associated with harm ? A pilot study using a nicotine inhaler. Nicotine & Tobacco Research 2000;2(4):327‐36. - PubMed
Hussain 2010 {published data only}
    1. Hussain S, Zawertailo L, Busto U, Zack M, Farvolden P, Selby P. The impact of chronic bupropion on plasma cotinine and on the subjective effects of ad lib smoking: a randomized controlled trial in unmotivated smokers. Addictive Behaviors 2010;35(2):164‐7. - PubMed
Jimenez‐Ruiz 2002 {published data only}
    1. Jimenez‐Ruiz C, Solano S, Viteri SA, Ferrero MB, Torrecilla M, Mezquita MH. Harm reduction ‐ A treatment approach for resistant smokers with tobacco‐related symptoms. Respiration 2002;69(5):452‐5. - PubMed
Karem‐Hage 2014 {published data only}
    1. Karam‐Hage M, Robinson JD, Lodhi A, Brower KJ. Bupropion‐SR for smoking reduction and cessation in alcohol‐dependent outpatients: a naturalistic, open‐label study. Current Clinical Pharmacology 2014;9(2):123‐9. - PMC - PubMed
Kelly 2010 {published data only}
    1. Kelly AC, Zuroff DC, Foa CL, Gilbert P. Who benefits from training in self‐compassionate self‐regulation? A study of smoking reduction. Journal of Social and Clinical Psychology 2010;29:727‐55.
Kotlyar 2007 {published data only}
    1. Kotlyar M, Mendoza‐Baumgart MI, Li ZZ, Pentel PR, Barnett BC, Feuer RM, et al. Nicotine pharmacokinetics and subjective effects of three potential reduced exposure products, moist snuff and nicotine lozenge. Tobacco Control 2007;16(2):138‐42. - PMC - PubMed
Lamb 2005 {published data only}
    1. Lamb RJ, Morral AR, Galbicka G, Kirby KC, Iguchi MY. Shaping reduced smoking in smokers without cessation plans. Experimental and Clinical Psychopharmacology 2005;13(2):83‐92. - PubMed
Lan 2007 {published data only}
    1. Lan TH, Chiu HJ, Wu BJ, Hung TH, Hu TM. Readiness to quit and smoking reduction outcomes. American Journal of Psychiatry 2007;164:827‐8. - PubMed
Leelarungrayub 2010 {published data only}
    1. Leelarungrayub D, Pratanaphon S, Pothongsunun P, Sriboonreung T, Yankai A, Bloomer RJ. Vernonia cinerea Less. supplementation and strenuous exercise reduce smoking rate: relation to oxidative stress status and beta‐endorphin release in active smokers. Journal of the International Society of Sports Nutrition 2010;7:21. - PMC - PubMed
Lichtenstein 2008 {published data only}
    1. Lichtenstein E, Boles SM, Lee ME, Hampson SE, Glasgow RE, Fellows J. Using radon risk to motivate smoking reduction II: randomized evaluation of brief telephone counseling and a targeted video. Health Education Research 2008;23(2):191‐201. - PubMed
Malchodi 2003 {published data only}
    1. Malchodi CS, Oncken C, Dornelas EA, Caramanica L, Gregonis E, Curry SL. The effects of peer counseling on smoking cessation and reduction. Obstetrics and Gynecology 2003;101(3):504‐10. - PubMed
McKinney 2014 {published data only}
    1. McKinney DL, Frost‐Pineda K, Oldham MJ, Fisher MT, Wang J, Gogova M, et al. Cigarettes with different nicotine levels affect sensory perception and levels of biomarkers of exposure in adult smokers. Nicotine & Tobacco Research 2014;16(7):948‐60. - PubMed
Mendoza‐Baumgart 2007 {published data only}
    1. Mendoza‐Baumgart MI, Tulunay OE, Hecht SS, Zhang Y, Murphy S, Le C, et al. Pilot study on lower nitrosamine smokeless tobacco products compared with medicinal nicotine. Nicotine & Tobacco Research 2007;9(12):1309‐23. - PubMed
NCT01944423 2013 {published data only}
    1. NCT01944423. Enhancing panic and smoking reduction treatment With D‐cycloserine [Enhancing panic and smoking reduction treatment with D‐cycloserine]. clinicaltrials.gov/show/NCT01944423 (first received 10th September 2013).
Ostroff 2014 {published data only}
    1. Ostroff JS, Burkhalter JE, Cinciripini PM, Li Y, Shiyko MP, Lam CY, et al. Randomized trial of a pre‐surgical, scheduled reduced smoking intervention for patients newly diagnosed with cancer. Psychooncology 2013;22:74‐5. - PMC - PubMed
    1. Ostroff JS, Burkhalter JE, Cinciripini PM, Li Y, Shiyko MP, Lam CY, et al. Randomized trial of a presurgical scheduled reduced smoking intervention for patients newly diagnosed with cancer. Health Psychology 2014;33(7):737‐47. - PMC - PubMed
Pisinger 2005 {published data only}
    1. Jørgensen T, Borch‐Johnsen K, Thomsen TF, Ibsen H, Glumer C, Pisinger C. A randomized non‐pharmacological intervention study for prevention of ischaemic heart disease: baseline results Inter99. Journal of Cardiovascular Risk 2003;10(5):377‐86. - PubMed
    1. Pisinger C, Jacobsen RK, Jørgensen T, The Inter99 Study Working Group. Final results from one of world’s largest population‐based randomized interventions on lifestyle. The Inter99 Study. Circulation 2013;127(12):A033.
    1. Pisinger C, Vestbo J, Borch‐Johnsen K, Jørgensen T. Smoking reduction intervention in a large population‐based study. The Inter99 study. Preventive Medicine 2005;40(1):112‐8. - PubMed
    1. Pisinger C, Vestbo J, Borch‐Johnsen K, Thomsen T, Jørgensen T. Acceptance of the smoking cessation intervention in a large population‐based study: the Inter99 study. Scandinavian Journal of Public Health 2005;33(2):138‐45. - PubMed
Pollak 2013 {published data only}
    1. Pollak KI, Lyna P, Bilheimer A, Farrell D, Gao X, Swamy GK, et al. A pilot study testing SMS text delivered scheduled gradual reduction to pregnant smokers. Nicotine & Tobacco Research 2013;15(10):1773‐6. - PMC - PubMed
Prapavessis 2014 {published data only}
    1. Prapavessis H, Jesus S, Harper T, Cramp A, Fitzgeorge L, Mottola MF, et al. The effects of acute exercise on tobacco cravings and withdrawal symptoms in temporary abstinent pregnant smokers. Addictive Behaviors 2014;39(3):703‐8. - PMC - PubMed
Prikryl 2014 {published data only}
    1. Prikryl R, Ustohal L, Kucerova HP, Kasparek T, Jarkovsky J, Hublova V, et al. Repetitive transcranial magnetic stimulation reduces cigarette consumption in schizophrenia patients. Progress in Neuro‐Psychopharmacology & Biological Psychiatry 2014;49:30‐5. - PubMed
Rennard 1990 {published data only}
    1. Rennard SI, Daughton D, Fujita J, Oehlerking MB, Dobson JR, Stahl MG, et al. Short‐term smoking reduction is associated with reduction in measures of lower respiratory tract inflammation in heavy smokers. European Respiratory Journal 1990;3(7):752‐9. - PubMed
Rennard 1994 {published and unpublished data}
    1. Rennard SI, Daughton D, Buchalter S, Floreani AA, Larson L, Millatmal T, et al. The influence of cigarette reduction or switching to lower nicotine yield cigarettes on measures of airway inflammation. American Review of Respiratory Disease 1994;149:A395.
Rennard 2002 {published data only}
    1. Rennard SI, Umino T, Millatmal T, Daughton DM, Manouilova LS, Ullrich FA, et al. Evaluation of subclinical respiratory tract inflammation in heavy smokers who switch to a cigarette‐like nicotine delivery device that primarily heats tobacco. Nicotine & Tobacco Research 2002;4(4):467‐76. - PubMed
Riggs 2001 {published data only}
    1. Riggs RL, Hughes JR, Pillitteri JL. Two behavioral treatments for smoking reduction: a pilot study. Nicotine & Tobacco Research 2001;3(1):71‐6. - PubMed
Robinson 1984 {published data only}
    1. Robinson JC, Young JC, Rickert WS. Maintain levels of nicotine but reduce other smoke constituents: A formula for 'less‐hazardous' cigarettes?. Preventive Medicine 1984;13(5):437‐45. - PubMed
Sarkar 2010 {published data only}
    1. Sarkar M, Liu J, Koval T, Wang J, Feng S, Serafin R, et al. Evaluation of biomarkers of exposure in adult cigarette smokers using Marlboro snus. Nicotine & Tobacco Research 2010;12(2):105‐16. - PubMed
Scherer 2006 {published data only}
    1. Scherer G, Urban M, Engl J, Hagedorn HW, Riedel K. Influence of smoking charcoal filter tipped cigarettes on various biomarkers of exposure. Inhalation Toxicology 2006;18(10):821‐9. - PubMed
Shi 2013 {published data only}
    1. Shi Y, Ehlers S, Hinds R, Baumgartner A, Warner DO. Monitoring of exhaled carbon monoxide to promote pre‐operative smoking abstinence (POS3‐111). Society for Research on Nicotine and Tobacco 18th Annual Meeting Proceedings. 2012.
    1. Shi Y, Ehlers S, Hinds R, Baumgartner A, Warner DO. Monitoring of exhaled carbon monoxide to promote preoperative smoking abstinence. Health Psychology 2013;32(6):714‐7. - PubMed
    1. Shi Y, Ehlers S, Warner DO. The theory of planned behavior as applied to preoperative smoking abstinence. PLoS ONE 2014;9:e103064. - PMC - PubMed
Shiffman 2009 {published data only}
    1. Shiffman S, Ferguson SG, Strahs KR. Quitting by gradual smoking reduction using nicotine gum: a randomized controlled trial. American Journal of Preventive Medicine 2009;36(2):96‐104. - PubMed
Spain NNCG‐008 {published data only}
    1. Pfizer Inc. Summary of Clinical Efficacy. Application for licensing of Nicorette Inhalator/Gum for smoking reduction leading to cessation. Company data NICORE‐1013‐273‐SU.
Stein 2002 {published data only}
    1. Stein JH, Bushara M, Bushara K, McBride PE, Jorenby DE, Fiore MC. Smoking cessation, but not smoking reduction, reduces plasma homocysteine levels. Clinical Cardiology 2002;25(1):23‐6. - PMC - PubMed
Strasser 2007 {published data only}
    1. Strasser AA, Lerman C, Sanborn PM, Pickworth WB, Feldman EA. New lower nicotine cigarettes can produce compensatory smoking and increased carbon monoxide exposure. Drug & Alcohol Dependence 2007;86(2‐3):294‐300. - PubMed
Sun 2009 {published data only}
    1. Sun HQ, Guo S, Chen DF, Jiang ZN, Liu Y, Di XL, et al. Family support and employment as predictors of smoking cessation success: a randomized, double‐blind, placebo‐controlled trial of nicotine sublingual tablets in Chinese smokers. American Journal of Drug and Alcohol Abuse 2009;35(3):183‐8. - PubMed
Tang 2013 {published data only}
    1. Tang YY, Tang R, Posner MI. Brief meditation training induces smoking reduction. Proceedings of the National Academy of Sciences of the United States of America 2013;110(34):13971‐5. - PMC - PubMed
Taylor 2014 {published data only}
    1. Taylor AH, Thompson TP, Greaves CJ, Taylor RS, Green C, Warren FC, et al. A pilot randomised trial to assess the methods and procedures for evaluating the clinical effectiveness and cost‐effectiveness of Exercise Assisted Reduction then Stop (EARS) among disadvantaged smokers. Health Technology Assessment 2014;18(4):1. - PMC - PubMed
    1. Thompson TP, Greaves CJ, Ayres R, Aveyard P, Warren FC, Byng R, et al. Lessons learned from recruiting socioeconomically disadvantaged smokers into a pilot randomized controlled trial to explore the role of Exercise Assisted Reduction then Stop (EARS) smoking.. Trials 2015;16:1. - PMC - PubMed
Tuten 2012 {published data only}
    1. Tuten M, Fitzsimons H, Chisolm MS, Nuzzo PA, Jones HE. Contingent incentives reduce cigarette smoking among pregnant, methadone‐maintained women: results of an initial feasibility and efficacy randomized clinical trial. Addiction 2012;107(10):1868‐77. - PMC - PubMed
Tønnesen 2005 {published data only}
    1. Tønnesen P, Pisinger C, Hvidberg S, Wennike P, Bremann L, Westin A, et al. Effects of smoking cessation and reduction in asthmatics. Nicotine & Tobacco Research 2005;7(1):139‐48. - PubMed
Windsor 1999 {published data only}
    1. Windsor RA, Li CQ, Boyd NR, Hartmann KE. The use of significant reduction rates to evaluate health education methods for pregnant smokers: A new harm reduction behavioral indicator?. Health Education & Behaviour 1999;26(5):648‐62. - PubMed
Wu 2013 {published data only}
    1. Wu BJ, Chen HK, Lee SM. A double‐blind randomized clinical trial of different doses of transdermal nicotine patch for smoking reduction and cessation in long‐term hospitalized schizophrenic patients. European Archives of Psychiatry and Clinical Neuroscience 2013;263:75‐82. - PubMed
    1. Wu BJ, Chen HK, Lee SM. Do atypical antipsychotics really enhance smoking reduction more than typical ones?: the effects of antipsychotics on smoking reduction in patients with schizophrenia. Journal of Clinical Psychopharmacology 2013;33(3):319‐28. - PubMed

References to ongoing studies

Caponetto 2014 {published data only}
    1. Caponnetto P, Polosa R, Auditore R, Minutolo G, Signorelli M, Maglia M, Alamo A, Palermo F, Aguglia E. Smoking cessation and reduction in schizophrenia (SCARIS) with e‐cigarette: study protocol for a randomized control trial. Trials 2014;15:88. - PMC - PubMed
    1. NCT01979796. Antismoking effects of electronic cigarettes in subjects with schizophrenia and their potential influence on cognitive functioning. (SCARIS) [Antismoking effects of electronic cigarettes in subjects with schizophrenia and their potential influence on cognitive functioning: Design of a randomized trial. Smoking Cessation And Reduction In Schizophrenia (The SCARIS Study)]. clinicaltrials.gov/ct2/show/NCT01979796 (first received 24th October 2013).
NCT02124187 {published data only}
    1. NCT02124187. Smoking cessation and reduction in depression (scarid) [Smoking cessation and reduction in depression (scarid)]. clinicaltrials.gov/show/NCT02124187 (first received 24th April 2014).
Taskila 2012 {published data only}
    1. Taskila T, Macaskill S, Coleman T, Etter JF, Patel M, Clarke S, et al. A randomised trial of nicotine assisted reduction to stop in pharmacies ‐ the RedPharm study. BMC Public Health 2012;12:182. - PMC - PubMed

Additional references

Anthonisen 2005
    1. Anthonisen NR, Skeans MA, Wise RA, Manfreda J, Kanner RE, Connett JE. The effects of a smoking cessation intervention on 14.5‐year mortality: a randomized clinical trial. Annals of Internal Medicine 2005;142(4):233‐9. - PubMed
Asfar 2011
    1. Asfar T, Ebbert JO, Klesges RC, Relyea GE. Do smoking reductioninterventions promote cessation in smokers not ready to quit?. Addictive Behaviors 2011;36(7):764‐8. - PMC - PubMed
Begh 2015
    1. Begh R, Lindson‐Hawley N, Aveyard P. Does reduced smoking if you can’t stop make any difference?. BMC Medicine 2015;13:257. - PMC - PubMed
Bilano 2015
    1. Bilano V, Gilmour S, Moffiet T, Tursan d’Espaignet E, Stevens GA, Commar A, et al. Global trends and projections for tobacco use, 1990–2025: an analysis of smoking indicators from the WHO Comprehensive Information Systems for Tobacco Control. Lancet 2015;385(9972):966‐76. - PubMed
Cahill 2016
    1. Cahill K, Lindson‐Hawley N, Thomas KH, Fanshawe TR, Lancaster T. Nicotine receptor partial agonists for smoking cessation. Cochrane Database of Systematic Reviews 2016, Issue 5. [DOI: 10.1002/14651858.CD006103.pub7] - DOI - PMC - PubMed
Doll 2004
    1. Doll R, Peto R, Boreham J, Sutherland I. Mortality in relation to smoking: 50 years' observations on male British doctors. BMJ 2004;328(7455):1519. - PMC - PubMed
GRADE 2012
    1. BMJ Clinical Evidence. What is GRADE?. clinicalevidence.bmj.com/x/set/static/ebm/learn/665072.html 2012 (accessed 6th October 2016).
Hart 2013
    1. Hart C, Gruer L, Bauld L. Does smoking reduction in midlife reduce mortality risk? Results of 2 long‐term prospective cohort studies of men and womenin Scotland. American Journal of Epidemiology 2013;178(5):770‐9. - PMC - PubMed
Hartmann‐Boyce 2016
    1. Hartmann‐Boyce J, McRobbie H, Bullen C, Begh R, Stead LF, Hajek P. Electronic cigarettes for smoking cessation. Cochrane Database of Systematic Reviews 2016, Issue 9. [DOI: 10.1002/14651858.CD010216.pub3] - DOI - PMC - PubMed
Hatsukami 2004
    1. Hatsukami DK, Henningfield JE, Kotlyar M. Harm reduction approaches to reducing tobacco‐related mortality. Annual Review of Public Health 2004;25:377–95. - PubMed
Hatsukami 2005a
    1. Hatsukami DK, Giovino GA, Eissenberg T, Clark PI, Lawrence D, Leischow S. Methods to assess potential reduced exposure products. Nicotine & Tobacco Research 2005;7(6):827‐44. - PubMed
Higgins 2003
    1. Higgins JP, Thompson SG, Deeks JJ, Altman DG. Measuring inconsistency in meta‐analyses. BMJ 2003;327(7414):557‐60. - PMC - PubMed
Higgins 2011
    1. Higgins JPT, Green S, editor(s). Cochrane Handbook for Systematic Reviews of Interventions. Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from handbook.cochrane.org.
Hughes 2003
    1. Hughes JR, Keely JP, Niaura RS, Ossip‐Klein DJ, Richmond RL, Swan GE. Measures of abstinence in clinical trials: issues and recommendations. Nicotine & Tobacco Research 2003;5(1):13‐25. - PubMed
Hughes 2005
    1. Hughes JR, Carpenter MJ. The feasibility of smoking reduction: an update. Addiction 2005;100:1074‐89. [DOI: 10.1111/j.1360-0443.2005.01174.x] - DOI - PMC - PubMed
Hughes 2006
    1. Hughes JR, Carpenter MJ. Does smoking reduction increase future cessation and decrease disease risk? A qualitative review. Nicotine & Tobacco Research 2006;8(6):739‐49. - PubMed
Hughes 2014
    1. Hughes JR, Stead LF, Hartmann‐Boyce J, Cahill K, Lancaster T. Antidepressants for smoking cessation. Cochrane Database of Systematic Reviews 2014, Issue 1. [DOI: 10.1002/14651858.CD000031.pub4] - DOI - PMC - PubMed
Levy 2004
    1. Levy DT, Mumford EA, Cummings KM, Gilpin EA, Giovino G, Hyland A, et al. The relative risks of a low‐nitrosamine smokeless tobacco product compared with smoking cigarettes: estimates of a panel of experts. Cancer Epidemiology, Biomarkers & Prevention 2004;13(12):2035‐42. - PubMed
Lindson‐Hawley 2012
    1. Lindson‐Hawley N, Aveyard P, Hughes JR. Reduction versus abrupt cessation in smokers who want to quit. Cochrane Database of Systematic Reviews 2012, Issue 11. [DOI: 10.1002/14651858.CD008033.pub2] - DOI - PubMed
Murrelle 2010
    1. Murrelle L, Coggins CR, Gennings C, Carchman RA, Carter WH Jr, Davies BD, et al. Hypotheses and fundamental study design characteristics for evaluating potential reduced‐risk tobacco products. Part I: Heuristic. Regulatory Toxicology and Pharmacology 2010;57(1):1‐10. - PubMed
NICE 2013
    1. National Institute for Health and Clinical Excellence (NICE). Smoking: harm reduction [PH45]. Available online: www.nice.org.uk/guidance/ph45?unlid=101942685820162262448 (Accessed 18th August 2016).
Pisinger 2007
    1. Pisinger C, Godtfredsen NS. Is there a health benefit of reduced tobacco consumption? A systematic review. Nicotine & Tobacco Research 2007;9(6):631‐46. - PubMed
Ramstrom 2014
    1. Ramstrom L, Wikmans T. Mortality attributable to tobacco among men in Sweden and other European countries: an analysis of data in a WHO report. Tobacco Induced Diseases 2014;12(1):14. - PMC - PubMed
Scherer 1999
    1. Scherer G. Smoking behaviour and compensation: a review of the literature. Psychopharmacology (Berl) 1999;145(1):1‐20. - PubMed
Shiffman 2002
    1. Shiffman S, Gitchell JG, Warner KE, Slade J, Henningfield JE, Pinney JM. Tobacco harm reduction: Conceptual structure and nomenclature for analysis and research. Nicotine & Tobacco Research 2002;4(Suppl 2):S113‐S129. - PubMed
Stead 2012
    1. Stead LF, Perera R, Bullen C, Mant D, Hartmann‐Boyce, Cahill K, et al. Nicotine replacement therapy for smoking cessation. Cochrane Database of Systematic Reviews 2012, Issue 11. [DOI: 10.1002/14651858.CD000146.pub4] - DOI - PubMed
Tverdal 2006
    1. Tverdal A, Bjartveit K. Health consequences of reduced daily cigarette consumption. Tobacco Control 2006;15(6):472‐80. - PMC - PubMed
UMN TTURC 2005
    1. University of Minnesota Cancer Centre Transdisciplinary Tobacco Use Research Group. Hope or hazard? What research tells us about "potentially reduced‐exposure" tobacco products. conservancy.umn.edu/bitstream/handle/11299/145/hope_or_hazard‐3.pdf?sequ.... University of Minnesota, 2005 (accessed 4th October 2016).
West 2005
    1. West R, Hajek P, Stead L, Stapleton J. Outcome criteria in smoking cessation trials: proposal for a common standard. Addiction 2005;100(3):299‐303. - PubMed
WHO 2003
    1. World Health Organization. WHO Framework Convention on Tobacco Control. Available online: apps.who.int/iris/bitstream/10665/42811/1/9241591013.pdf. Geneva: World Health Organization, 2003 (accessed 18th August 2016).
WHO 2013
    1. World Health Organization. Global action plan for the prevention and control of NCDs 2013 ‐ 2020. Available online: apps.who.int/iris/bitstream/10665/94384/1/9789241506236_eng.pdf?ua=1 (accessed 18th August 2016).

References to other published versions of this review

Stead 2005
    1. Stead LF, Hey K, Lancaster T. Interventions to reduce harm from continued tobacco use. Cochrane Database of Systematic Reviews 2005, Issue 2. [DOI: 10.1002/14651858.CD005231] - DOI - PubMed
Stead 2007
    1. Stead LF, Lancaster T. Interventions to reduce harm from continued tobacco use. Cochrane Database of Systematic Reviews 2007, Issue 3. [DOI: 10.1002/14651858.CD005231.pub2] - DOI - PubMed

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