Smoking reduction fails to improve clinical and biological markers of cardiac disease: a randomized controlled trial

Systematic review and meta-analysis investigating nicotine, cotinine and carbon monoxide exposures in people who both smoke and use nicotine replacement therapy

AIMS

To determine effects of concurrent smoking and nicotine replacement therapy (NRT) use on reported heaviness of smoking, nicotine (cotinine) body fluid and exhaled air carbon monoxide (CO) concentrations.

METHODS

Systematic review and meta-analysis of RCTs, which test interventions permitting concurrent NRT use and smoking and comparing, within participants, outcomes when smoking with those when smoking and using NRT concurrently. Measurements included reported number of cigarettes smoked per day (CPD), body fluid cotinine and expired air CO concentrations.

RESULTS

Twenty-nine studies were included in the review. Meta-analysis of nine showed that, compared with when solely smoking, fewer cigarettes were smoked daily when NRT was used (mean difference during concurrent smoking and NRT use, -2.06 CPD [95% CI = -3.06 to -1.07, P < 0.0001]). Meta-analysis of seven studies revealed a non-significant reduction in exhaled CO during concurrent smoking and NRT use (mean difference, -0.58 ppm [95% CI = -2.18 to 1.03, P = 0.48]), but in the three studies that tested NRT used in the lead-up to quitting (i.e. as preloading), a similar reduction in exhaled CO was statistically significant (mean difference, -2.54 ppm CO [95% CI = -4.14 to -0.95, P = 0.002]). Eleven studies reported cotinine concentrations, but meta-analysis was not possible because of data reporting heterogeneity; of these, seven reported lower cotinine concentrations with concurrent NRT use and smoking, four reported no differences, and none reported higher concentrations.

CONCLUSIONS

People who smoke and also use nicotine replacement therapy report smoking less heavily than people who solely smoke. When nicotine replacement therapy is used in the lead-up to quitting (preloading), this reported smoking reduction has been biochemically confirmed. There is no evidence that concurrent smoking and nicotine replacement therapy use result in greater nicotine exposure than solely smoking.

Interleukins and redox impairment in type 2 diabetes mellitus: mini-review and pilot study

BACKGROUND

Type 2 diabetes mellitus (T2DM) represents a leading cause of morbidity and premature mortality, low-grade inflammation being acknowledged as a key contributor to its development and progression. A tailored therapeutic approach, based on sensitive and specific biomarkers, could allow a more accurate analysis of disease susceptibility/prognostic and of the response to treatment.

OBJECTIVES

This mini-review and pilot study had two main goals: (1) reviewing the most recent literature encompassing the use of interleukins as inflammatory markers influenced by the redox imbalances in T2DM and (2) assessing parameters that conjunctly evaluate the redox impairment and inflammatory burden of T2DM patients, taking into consideration smoking status, as such group-specific biomarkers are scarcely reported in literature.

METHODS

Firstly, PubMed database was surveyed to select and review the relevant studies employing interleukins as T2DM biomarkers and to assess if studies using combined inflammatory-redox indices were reported. Then, routine biochemical parameters were assessed in a pilot study -T2DM patients with 3 subgroups: non-smokers, smokers and ex-smokers, were compared to a control group of non-diabetic, apparently healthy non-smokers. Protein (AOPPs, AGEs), lipid/HDL (Amplex Red-based method) oxidative damage and inflammatory status (CRP, IL-1β, IL-6, IL-10) biomarkers were assessed. Cytokine ratios and 2 oxidative-inflammatory status indices were developed (IH1 and IH2) and evaluated.

RESULTS

We observed significant differences in terms of serum redox and inflammatory status (AOPPs, AGEs, CRP, CRP/HDL, CRP/IL-6, IL-10/IL-6, IH1) between T2DM patients compared to control and, moreover, between the subgroups formed considering smoking status (CRP, CRP/HDL, IH1). Glycemic control strongly influenced inflammatory status biomarkers: glycemia was positively correlated with the inflammatory parameters (CRP/IL-10) and inversely with the anti-inflammatory ones (IL-10, IL-10/IL-1β ratio).

CONCLUSIONS

Several of the assessed parameters may possess prognostic value for diabetics, especially when comparing subgroups with a different smoking history and could prove useful in clinical practice for assessing disease progress and therapeutic efficacy.

Assessment of a Personal Interactive Carbon Monoxide Breath Sensor in People Who Smoke Cigarettes: Single-Arm Cohort Study

Background

Tobacco use is the leading cause of preventable morbidity and mortality. Existing evidence-based treatments are underutilized and have seen little recent innovation. The success of personal biofeedback interventions in other disease states portends a similar opportunity in smoking cessation. The Pivot Breath Sensor is a personal interactive FDA-cleared (over-the-counter) device that measures carbon monoxide (CO) in exhaled breath, enabling users to link their smoking behavior and CO values, and track their progress in reducing or quitting smoking.

Objective

The objective of this study is to assess the Pivot Breath Sensor in people who smoke cigarettes, evaluating changes in attitudes toward quitting smoking, changes in smoking behavior, and use experience.

Methods

US adults (18-80 years of age, ≥10 cigarettes per day [CPD]) were recruited online for this remote 12-week study. Participants completed a screening call, informed consent, and baseline questionnaire, and then were mailed their sensor. Participants were asked to submit 4 or more breath samples per day and complete questionnaires at 1-4, 8, and 12 weeks. Outcomes included attitudes toward quitting smoking (Stage of Change, success to quit, and perceived difficulty of quitting), smoking behavior (quit attempts, CPD reduction, and 7-, 30-day point prevalence abstinence [PPA]), and use experience (impact and learning).

Results

Participants comprised 234 smokers, mean age 39.9 (SD 11.3) years, 52.6% (123/234) female, mean CPD 20.3 (SD 8.0). The 4- and 12-week questionnaires were completed by 92.3% (216/234) and 91.9% (215/234) of participants, respectively. Concerning attitude outcomes, at baseline, 15.4% (36/234) were seriously thinking of quitting in the next 30 days, increasing to 38.9% (84/216) at 4 weeks and 47.9% (103/215) at 12 weeks (both P<.001). At 12 weeks, motivation to quit was increased in 39.1% (84/215), unchanged in 54.9% (118/215), and decreased in 6.0% (13/215; P<.001). Additional attitudes toward quitting improved from baseline to 12 weeks: success to quit 3.3 versus 5.0 (P<.001) and difficulty of quitting 2.8 versus 4.3 (P<.001). Regarding smoking behavior, at 4 weeks, 28.2% (66/234) had made 1 or more quit attempts (≥1 day of abstinence), increasing to 48.3% (113/234) at 12 weeks. At 4 weeks, 23.1% (54/234) had reduced CPD by 50% or more, increasing to 38.5% (90/234) at 12 weeks. At 12 weeks, CPD decreased by 41.1% from baseline (P<.001), and 7- and 30-day PPA were 12.0% (28/234) and 6.0% (14/234), respectively. Concerning use experience, 75.3% (171/227) reported the sensor increased their motivation to quit. More than 90% (>196/214) indicated the sensor taught them about their CO levels and smoking behavior, and 73.1% (166/227) reported that seeing their CO values made them want to quit smoking.

Conclusions

Use of the Pivot Breath Sensor resulted in a significant increase in motivation to quit, a reduction in CPD, and favorable quit attempt rates. These outcomes confer increased likelihood of quitting smoking. Accordingly, the results support a role for biofeedback via personal CO breath sampling in smoking cessation.

Trial Registration

ClinicalTrials.gov NCT04133064; https://clinicaltrials.gov/ct2/show/NCT04133064

Counseling alone or in combination with nicotine replacement therapy for treatment of black non-daily smokers: a randomized trial

BACKGROUND AND AIMS

One-third of US tobacco users are non-daily smokers (NDS). Black NDS have strikingly high levels of nicotine and carcinogen exposure. No smoking cessation studies have been conducted with this high-risk group. This study compared the effectiveness in black NDS of smoking cessation counseling alone or in combination with the participant's choice of nicotine replacement therapy.

DESIGN

Two-arm parallel-group individually randomized clinical trial (allocation ratio of 2 : 1 intervention to control) SETTING: Academic medical and federally qualified health centers in three US cities.

PARTICIPANTS

Non-Hispanic black adult NDS receiving counseling with nicotine replacement therapy (C + NRT, n = 185) or counseling alone (C, n = 93).

INTERVENTIONS

Twelve weeks of in-person and telephone smoking cessation counseling in combination with nicotine replacement therapy (NRT; C + NRT) or counseling alone (C). All participants received five sessions of counseling; those randomized to C + NRT received their choice of nicotine gum, patch and/or lozenge after a 9-day product trial period. The target quit day was set at 2 weeks post-baseline for both groups.

MEASUREMENTS

Primary outcome was biochemically verified 30-day abstinence at week 12. Secondary outcomes were change in nicotine and carcinogen exposure [4-(methynitrosamino)-1-(3) pyridyle-1-butanol; NNAL] and tobacco consumption patterns.

FINDINGS

Abstinence was 11.4% in C + NRT and 8.6% in C [odds ratio (OR) = 1.4, 95% confidence interval (CI) = 0.6, 3.2, P = 0.48]. Both groups experienced significant reduction in NNAL (C + NRT: 53% reduction, C: 50% reduction, within-group P < 0.0001) but non-significant changes in cotinine (P = 0.69). C + NRT reported more days abstinent (P < 0.001) and fewer total cigarettes (P = 0.002) compared with C. There was no evidence of compensation with other tobacco products.

CONCLUSIONS

Among black non-daily smokers in the United States, there was no difference in abstinence between nicotine replacement therapy (NRT) and counseling alone. NRT led to greater increase in days abstinent and reduction in cigarettes, with no evidence of compensation from other sources of nicotine.

Smoking reduction interventions for smoking cessation

BACKGROUND

The standard way most people are advised to stop smoking is by quitting abruptly on a designated quit day. However, many people who smoke have tried to quit many times and may like to try an alternative method. Reducing smoking behaviour before quitting could be an alternative approach to cessation. However, before this method can be recommended it is important to ensure that abrupt quitting is not more effective than reducing to quit, and to determine whether there are ways to optimise reduction methods to increase the chances of cessation.

OBJECTIVES

To assess the effect of reduction-to-quit interventions on long-term smoking cessation.

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group Specialised Register, MEDLINE, Embase and PsycINFO for studies, using the terms: cold turkey, schedul*, cut* down, cut-down, gradual*, abrupt*, fading, reduc*, taper*, controlled smoking and smoking reduction. We also searched trial registries to identify unpublished studies. Date of the most recent search: 29 October 2018.

SELECTION CRITERIA

Randomised controlled trials in which people who smoked were advised to reduce their smoking consumption before quitting smoking altogether in at least one trial arm. This advice could be delivered using self-help materials or behavioural support, and provided alongside smoking cessation pharmacotherapies or not. We excluded trials that did not assess cessation as an outcome, with follow-up of less than six months, where participants spontaneously reduced without being advised to do so, where the goal of reduction was not to quit altogether, or where participants were advised to switch to cigarettes with lower nicotine levels without reducing the amount of cigarettes smoked or the length of time spent smoking. We also excluded trials carried out in pregnant women.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods. Smoking cessation was measured after at least six months, using the most rigorous definition available, on an intention-to-treat basis. We calculated risk ratios (RRs) and 95% confidence intervals (CIs) for smoking cessation for each study, where possible. We grouped eligible studies according to the type of comparison (no smoking cessation treatment, abrupt quitting interventions, and other reduction-to-quit interventions) and carried out meta-analyses where appropriate, using a Mantel-Haenszel random-effects model. We also extracted data on quit attempts, pre-quit smoking reduction, adverse events (AEs), serious adverse events (SAEs) and nicotine withdrawal symptoms, and meta-analysed these where sufficient data were available.

MAIN RESULTS

We identified 51 trials with 22,509 participants. Most recruited adults from the community using media or local advertising. People enrolled in the studies typically smoked an average of 23 cigarettes a day. We judged 18 of the studies to be at high risk of bias, but restricting the analysis only to the five studies at low or to the 28 studies at unclear risk of bias did not significantly alter results.We identified very low-certainty evidence, limited by risk of bias, inconsistency and imprecision, comparing the effect of reduction-to-quit interventions with no treatment on cessation rates (RR 1.74, 95% CI 0.90 to 3.38; I2 = 45%; 6 studies, 1599 participants). However, when comparing reduction-to-quit interventions with abrupt quitting (standard care) we found evidence that neither approach resulted in superior quit rates (RR 1. 01, 95% CI 0.87 to 1.17; I2 = 29%; 22 studies, 9219 participants). We judged this estimate to be of moderate certainty, due to imprecision. Subgroup analysis provided some evidence (P = 0.01, I2 = 77%) that reduction-to-quit interventions may result in more favourable quit rates than abrupt quitting if varenicline is used as a reduction aid. Our analysis comparing reduction using pharmacotherapy with reduction alone found low-certainty evidence, limited by inconsistency and imprecision, that reduction aided by pharmacotherapy resulted in higher quit rates (RR 1. 68, 95% CI 1.09 to 2.58; I2 = 78%; 11 studies, 8636 participants). However, a significant subgroup analysis (P < 0.001, I2 = 80% for subgroup differences) suggests that this may only be true when fast-acting NRT or varenicline are used (both moderate-certainty evidence) and not when nicotine patch, combination NRT or bupropion are used as an aid (all low- or very low-quality evidence). More evidence is likely to change the interpretation of the latter effects.Although there was some evidence from within-study comparisons that behavioural support for reduction to quit resulted in higher quit rates than self-help resources alone, the relative efficacy of various other characteristics of reduction-to-quit interventions investigated through within- and between-study comparisons did not provide any evidence that they enhanced the success of reduction-to-quit interventions. Pre-quit AEs, SAEs and nicotine withdrawal symptoms were measured variably and infrequently across studies. There was some evidence that AEs occurred more frequently in studies that compared reduction using pharmacotherapy versus no pharmacotherapy; however, the AEs reported were mild and usual symptoms associated with NRT use. There was no clear evidence that the number of people reporting SAEs, or changes in withdrawal symptoms, differed between trial arms.

AUTHORS' CONCLUSIONS

There is moderate-certainty evidence that neither reduction-to-quit nor abrupt quitting interventions result in superior long-term quit rates when compared with one another. Evidence comparing the efficacy of reduction-to-quit interventions with no treatment was inconclusive and of low certainty. There is also low-certainty evidence to suggest that reduction-to-quit interventions may be more effective when pharmacotherapy is used as an aid, particularly fast-acting NRT or varenicline (moderate-certainty evidence). Evidence for any adverse effects of reduction-to-quit interventions was sparse, but available data suggested no excess of pre-quit SAEs or withdrawal symptoms. We downgraded the evidence across comparisons due to risk of bias, inconsistency and imprecision. Future research should aim to match any additional components of multicomponent reduction-to-quit interventions across study arms, so that the effect of reduction can be isolated. In particular, well-conducted, adequately-powered studies should focus on investigating the most effective features of reduction-to-quit interventions to maximise cessation rates.

Smoking Cessation for Smokers Not Ready to Quit: Meta-analysis and Cost-effectiveness Analysis

CONTEXT

To provide a systematic review and cost-effectiveness analysis on smoking interventions targeting smokers not ready to quit, a population that makes up approximately 32% of current smokers.

EVIDENCE ACQUISITION

Twenty-two studies on pharmacological, behavioral, and combination smoking-cessation interventions targeting smokers not ready to quit (defined as those who reported they were not ready to quit at the time of the study) published between 2000 and 2017 were analyzed. The effectiveness (measured by the number needed to treat) and cost effectiveness (measured by costs per quit) of interventions were calculated. All data collection and analyses were performed in 2017.

EVIDENCE SYNTHESIS

Smoking interventions targeting smokers not ready to quit can be as effective as similar interventions for smokers ready to quit; however, costs of intervening on this group may be higher for some intervention types. The most cost-effective interventions identified for this group were those using varenicline and those using behavioral interventions.

CONCLUSIONS

Updating clinical recommendations to provide cessation interventions for this group is recommended. Further research on development of cost-effective treatments and effective strategies for recruitment and outreach for this group are needed. Additional studies may allow for more nuanced comparisons of treatment types among this group.

Strategies to decrease oxidative stress biomarker levels in human medical conditions: A meta-analysis on 8-iso-prostaglandin F2α

The widespread detection of elevated oxidative stress levels in many medical conditions has led to numerous efforts to design interventions to reduce its effects. Efforts have been wide-ranging, from dietary changes to administration of antioxidants, supplements, e.g., omega-3-fatty acids, and many medications. However, there is still no systemic assessment of the efficacy of treatments for oxidative stress reduction across a variety of medical conditions. The goal of this meta-analysis is, by combining multiple studies, to quantitate the change in the levels of the popular oxidative stress biomarker 8-iso-prostaglandin F2α (8-iso-PGF2α) after a variety of treatment strategies in human populations. Nearly 350 unique publications with 180 distinct strategies were included in the analysis. For each strategy, the difference between pre- or placebo and post-treatment levels calculated using Hedges' g value of effect. In general, administration of antibiotics, antihyperlipidemic agents, or changes in lifestyle (g = - 0.63, - 0.54, and 0.56) had the largest effect. Administration of supplements, antioxidants, or changes in diet (g = - 0.09, - 0.28, - 0.12) had small quantitative effects. To fully interpret the effectiveness of these treatments, comparisons to the increase in g value for each medical condition is required. For example, antioxidants in populations with coronary artery disease (CAD) reduce the 8-iso-PGF2α levels by g = - 0.34 ± 0.1, which is quantitatively considered a small effect. However, CAD populations, in comparison to healthy populations, have an increase in 8-iso-PGF2α levels by g = 0.38 ± 0.04; therefore, the overall reduction of 8-iso-PGF2α levels is ≈ 90% by this treatment in this specific medical condition. In conclusion, 8-iso-PGF2α levels can be reduced not only by antioxidants but by many other strategies. Not all strategies are equally effective at reducing 8-iso-PGF2α levels. In addition, the effectiveness of any strategy can be assessed only in relation to the medical condition investigated.

Self-Care for the Prevention and Management of Cardiovascular Disease and Stroke: A Scientific Statement for Healthcare Professionals From the American Heart Association

Self-care is defined as a naturalistic decision-making process addressing both the prevention and management of chronic illness, with core elements of self-care maintenance, self-care monitoring, and self-care management. In this scientific statement, we describe the importance of self-care in the American Heart Association mission and vision of building healthier lives, free of cardiovascular diseases and stroke. The evidence supporting specific self-care behaviors such as diet and exercise, barriers to self-care, and the effectiveness of self-care in improving outcomes is reviewed, as is the evidence supporting various individual, family-based, and community-based approaches to improving self-care. Although there are many nuances to the relationships between self-care and outcomes, there is strong evidence that self-care is effective in achieving the goals of the treatment plan and cannot be ignored. As such, greater emphasis should be placed on self-care in evidence-based guidelines.

Interventions to reduce harm from continued tobacco use

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.

A Randomized Trial Comparing the Effect of Nicotine Versus Placebo Electronic Cigarettes on Smoking Reduction Among Young Adult Smokers

INTRODUCTION

Electronic cigarette (EC) use is growing dramatically with use highest among young adults and current smokers. One of the most common reasons for using ECs is interest in quitting or reducing cigarettes per day (CPD); however there are few randomized controlled trials (RCT) on the effect of ECs on smoking abstinence and reduction.

METHODS

We conducted a two-arm; double-blind RCT. Subjects were randomized to receive 3-weeks of either disposable 4.5% nicotine EC (intervention) or placebo EC. The primary outcome was self-reported reduction of at least 50% in the number of CPDs smoked at week 3 (end of treatment) compared to baseline. Study subjects (n = 99) were young adult (21-35), current smokers (smoked ≥ 10 CPDs) living in NYC.

RESULTS

Compared with baseline, a significant reduction in CPDs was observed at both study time periods (1 and 3 weeks) for intervention (P < .001) and placebo (P < .001) groups. Between-group analyses showed significantly fewer CPDs in the intervention group compared to the placebo group at week 3 (P = .03), but not at any other follow-up periods. The logistic regression analysis showed that using a greater number of ECs, treatment condition and higher baseline readiness to quit were significantly associated with achieving at least 50% reduction in CPDs at the end of treatment.

CONCLUSION

A diverse young adult sample of current everyday smokers, who were not ready to quit, was able to reduce smoking with the help of ECs. Further study is needed to establish the role of both placebo and nicotine containing ECs in increasing both reduction and subsequent cessation.

IMPLICATIONS

Despite the critical need for well-designed clinical trials on the effect of ECs on cessation and cigarette reduction, the majority of studies have been observational or noncomparative intervention designs. Only three RCTs studying ECs as a cessation or reduction intervention have been published, and none were conducted in the United States. The current study adds knowledge to current literature on the feasibility of using ECs to aid smoking reduction among young smokers in US urban populations.

Characterizing use patterns and perceptions of relative harm in dual users of electronic and tobacco cigarettes

Awareness and use of electronic cigarettes (e-cigarettes) is increasing. Questions regarding positive (e.g., smoking reduction/cessation) and negative (e.g., delay of cessation) potential public health consequences of e-cigarettes may be informed by studying dual users of e-cigarettes and tobacco cigarettes. A cross-sectional online survey assessed demographics, product use patterns, and beliefs about relative product benefits and harms among dual users (n = 350) in the United States using the website Amazon Mechanical Turk. Compared to tobacco cigarettes, e-cigarettes were used less often and were associated with lower dependence. Participants reported a 30% reduction in self-reported tobacco cigarette smoking since beginning to use e-cigarettes. Reported primary reasons for e-cigarette use were harm reduction and smoking cessation. E-cigarette use was reported as more likely in settings with smoking restrictions and when others' health could be adversely affected. Conversely, participants reported having used tobacco cigarettes more often than e-cigarettes in hedonic situations (e.g., after eating, drinking coffee or alcohol, or having sex), outdoors, or when stressed. Participants were twice as likely to report wanting to quit tobacco cigarettes compared to e-cigarettes in the next year and intended to quit tobacco cigarettes sooner. Tobacco cigarettes were described as more harmful and addictive, but also as more enjoyable than e-cigarettes. Participants provided evidence consistent with both positive and negative public health consequences of e-cigarettes, highlighting the need for experimental research, including laboratory studies and clinical trials. Policies should consider potential public health benefits of e-cigarettes, in addition to potential harms.

Effect of Smoking Reduction Therapy on Smoking Cessation for Smokers without an Intention to Quit: An Updated Systematic Review and Meta-Analysis of Randomized Controlled

OBJECTIVE

Effective strategies are needed to encourage smoking cessation for smokers without an intention to quit. We systematically reviewed the literature to investigate whether smoking reduction therapy can increase the long-term cessation rates of smokers without an intention to quit.

METHODS

PubMed, Embase, and CENTRAL (Cochrane Central Register of Controlled Trials) were searched for randomized controlled trials (RCTs) on the effect of smoking reduction therapy on long-term smoking cessation in smokers without an intention to quit. The primary outcome was the cessation rate at the longest follow-up period. A random effects model was used to calculate pooled relative risks (RRs) and 95% confidence intervals (CIs).

RESULTS

Fourteen trials with a total of 7981 smokers were included. The pooled analysis suggested that reduction support plus medication significantly increased the long-term cessation of smokers without an intention to quit compared to reduction support plus placebo (RR, 1.97; 95% CI, 1.44-2.7; I(2), 52%) or no intervention (RR, 1.93; 95% CI, 1.41-2.64; I(2), 46%). In a subgroup of smokers who received varenicline or nicotine replacement therapy (NRT), the differences were also statistically significant. This suggests the safety of using NRT. The percentage of smokers with serious adverse events who discontinued because of these events in the non-NRT group was slightly significantly different than in the control group. Insufficient evidence is available to test the efficacy of reduction behavioural support in promoting long-term cessation among this population.

CONCLUSIONS

The present meta-analysis indicated the efficacy of NRT- and varenicline-assisted reduction to achieve complete cessation among smokers without an intention to quit. Further evidence is needed to assess the efficacy and safety of reduction behavioural support and bupropion.

A Review of the Literature Concerning HIV and Cigarette Smoking: Morbidity and Mortality, Associations with Individual- and Social-Level Characteristics, and Smoking Cessation Efforts

Cigarette smoking is endemic among many populations, but is especially prevalent among people living with HIV, and is consequently associated with a variety of types of morbidity as well as mortality. Despite this knowledge, relatively little research has been conducted among smokers living with HIV. Extant research has focused on examining individual-level characteristics associated with smoking behaviors, to the neglect of examining social-level factors. This manuscript represents a critical literature review of the intersecting research fields of HIV and cigarette smoking. Topics considered within this review include: morbidity, mortality, as well as treatment and medication adherence outcomes; individual- and social-level characteristics associated with various smoking behaviors; evidence-based smoking cessation interventions; and findings from cessation interventions among smokers living with HIV. Additionally, gaps in the existing literature, as well as directions for future research were identified and discussed.

Beyond cigarettes per day. A genome-wide association study of the biomarker carbon monoxide

RATIONALE

The CHRNA5-CHRNA3-CHRNB4 locus is associated with self-reported smoking behavior and also harbors the strongest genetic associations with chronic obstructive pulmonary disease (COPD) and lung cancer. Because the associations with lung disease remain after adjustment for self-reported smoking behaviors, it has been asserted that CHRNA5-CHRNA3-CHRNB4 variants increase COPD and lung cancer susceptibility independently of their effects on smoking.

OBJECTIVES

To compare the genetic associations of exhaled carbon monoxide (CO), a biomarker of current cigarette exposure, with self-reported smoking behaviors.

METHODS

A total of 1,521 European American and 247 African American current smokers recruited into smoking cessation studies were assessed for CO at intake before smoking cessation. DNA samples were genotyped using the Illumina Omni2.5 microarray. Genetic associations with CO and smoking behaviors (cigarettes smoked per day, Fagerstrom test for nicotine dependence) were studied.

MEASUREMENTS AND MAIN RESULTS

Variants in the CHRNA5-CHRNA3-CHRNB4 locus, including rs16969968, a nonsynonymous variant in CHRNA5, are genomewide association study-significantly associated with CO (β = 2.66; 95% confidence interval [CI], 1.74-3.58; P = 1.65 × 10(-8)), and this association remains strong after adjusting for smoking behavior (β = 2.18; 95% CI, 1.32-3.04; P = 7.47 × 10(-7)). The correlation between CO and cigarettes per day is statistically significantly lower (z = 3.43; P = 6.07 × 10(-4)) in African Americans (r = 0.14; 95% CI, 0.02-0.26; P = 0.003) than in European-Americans (r = 0.36; 95% CI, 0.31-0.40; P = 0.0001).

CONCLUSIONS

Exhaled CO, a biomarker that is simple to measure, captures aspects of cigarette smoke exposure in current smokers beyond the number of cigarettes smoked per day. Behavioral measures of smoking are therefore insufficient indices of cigarette smoke exposure, suggesting that genetic associations with COPD or lung cancer that persist after adjusting for self-reported smoking behavior may still reflect genetic effects on smoking exposure.

Clinical strategies to enhance the efficacy of nicotine replacement therapy for smoking cessation: a review of the literature

A number of smoking cessation pharmacotherapies have led to increases in quitting and thus to significant benefits to public health. Among existing medications, nicotine replacement therapy (NRT) has been available the longest, has the largest literature base in support, and is the only option for over-the-counter access. While the short-term efficacy of NRT is well documented in clinical trials, long-term abstinence rates associated with using NRT are modest, as most smokers will relapse. This literature review examines emerging clinical strategies to improve NRT efficacy. After an initial overview of NRT and its FDA-approved indications for use, we review randomized trials in which clinical delivery of NRT was manipulated and tested, in an attempt to enhance efficacy, through (1) duration of use (pre-quit and extended use), (2) amount of use (high-dose and combination NRT), (3) tailoring to specific smoker groups (genotype and phenotype), or (4) use of NRT for novel purposes (relapse prevention, temporary abstinence, cessation induction). Outcomes vary within and across topic area, and we highlight areas that offer stronger promise. Combination NRT likely represents the most promising strategy moving forward; other clinical strategies offer conflicting evidence but deserve further testing (pre-quit NRT or tailored treatment) or offer potential utility but are in need of further, direct tests. Some areas, though based on a limited set of studies, do not offer great promise (high-dose and extended treatment NRT). We conclude with a brief discussion of emergent NRT products (e.g., oral nicotine spray, among others), which may ultimately offer greater efficacy than current formulations. In order to further lower the prevalence of smoking, novel strategies designed to optimize NRT efficacy are needed.

Effect of tobacco smoking and smoking cessation on plasma lipoproteins and associated major cardiovascular risk factors: a narrative review

Cigarette smoking, active or passive, kills about 6 million people each year worldwide. Cardiovascular disease (CVD) is responsible for 40% of all smoking-related deaths, lung cancer accounts for 20% of all smoking-related deaths, and chronic obstructive pulmonary disease is related to another 20% of deaths. In this narrative review we consider the relationship between cigarette smoking and CVD. We discuss disease states and/or CVD risk factors related to smoking, such as dyslipidaemia, vascular inflammation, endothelial dysfunction, arterial stiffness, insulin resistance, type 2 diabetes mellitus (T2DM), chronic kidney disease (CKD), and non-alcoholic fatty liver disease (NAFLD) as well as their complex interrelations. Smoking cessation can correct abnormalities related to smoking; however, success rates are relatively low. In cases of inability to quit, measures to minimize the adverse effects of smoking specifically related to CVD should be taken. Smokers should receive best practice treatment, according to guidelines, as for non-smokers.

An exploratory analysis of the impact of a university campus smoking ban on staff and student smoking habits in Japan

Background

Smoking bans in public places have been shown to have an impact on smoking habits, however the potential influence of a university smoking ban on faculty and staff smoking habits remains elusive.

Methods

This cross sectional study was implemented in Nayoro City, Japan in 2011, among the faculty and students of the Nayoro City University. Five years after the declaration of a total ban on smoking on a university campus, the smoking characteristics of all students, teachers and office workers, and the policy’s impact on smokers were investigated. The survey was conducted through an anonymous, self-administered, multiple-choice questionnaire. Information was gathered on the characteristics and smoking characteristics of respondents, and the smokers attitudes toward smoking.

Results

The recovery rate was 62.1%. Among respondents, smoking prevalence was 17.9% in teachers and office workers, and 4.0% in students. Among all smokers, 46.4% did not abstain from smoking while at the university and they indicated their smoking areas were “on the streets next to the campus”: 16 and “outdoors on campus”: 3, respectively. As for smokers, 29.6% of them reduced the number of cigarettes smoked per day as a result of the smoking ban. None of the ex-smokers replied that their principal motivation for quitting smoking was the smoking ban.

Conclusions

The ban on smoking served a motivator for smokers to reduce in smoking, but not serve as an effective motivator to quit smoking.

Does smoking reduction make smokers happier? Evidence from a cross-sectional survey

Objectives: Stopping smoking leads to greater happiness and life satisfaction. This raises the question as to whether harm reduction, i.e. smoking reduction (SR) and the use of Nicotine Replacement Therapy (NRT) for SR, might lead to a similar benefit. This is of importance, given that the National Institute of Clinical Excellence in the UK is due to release guidance on harm reduction in 2013.

Design: Data were collected from 1,532 smokers involved in the Smoking Toolkit Study.

Method: Participants were asked if they were cutting down and if they were using Nicotine Replacement Therapy (NRT). Smokers also rated happiness and life satisfaction.

Results: There was no evidence of an association between SR or use of NRT for SR and either reported ‘happiness’ or ‘life satisfaction’. Nor was there an association between measures of ‘happiness’ or ‘life satisfaction’ and cigarette consumption.

Conclusion: It appears that SR is not associated with mental health benefits. This suggests that complete cessation may be necessary for benefits to be incurred. Prospective studies are necessary to confirm these findings.

Reduced exposure evaluation of an Electrically Heated Cigarette Smoking System. Part 7: A one-month, randomized, ambulatory, controlled clinical study in Poland

This randomized, open-label, ambulatory, controlled clinical study investigated biomarkers associated with cardiovascular risk and biomarkers of exposure to 10 selected harmful and potentially harmful constituents (HPHC) in cigarette smoke in 316 male and female Polish smokers. Subjects were randomized to continue smoking conventional cigarettes (CC; N=79) or switch to smoking the Electrically Heated Cigarette Smoking System series-K cigarette (EHCSS-K6; N=237). Biomarker assessments were performed at several time points during the study at baseline and during the 1-month investigational period. The primary biomarkers were high-sensitivity C-reactive protein and white blood cell counts. No statistically significant differences in the two primary biomarkers were found between the study groups at the end of the study. End-of-study comparisons of secondary biomarkers between study groups indicated an increase in high-density lipoprotein cholesterol, and reductions in red blood cell count, hemoglobin, and hematocrit levels in the EHCSS-K6 group. All biomarkers of exposure to cigarette smoke HPHC were decreased in the EHCSS-K6 group, despite an increase in cigarette consumption, compared to the CC group. There were no apparent differences in any of the safety assessment parameters between the groups, and the overall incidence of study-related adverse events was low.

Mediation analysis of the association between use of NRT for smoking reduction and attempts to stop smoking

OBJECTIVES

Use of nicotine replacement therapy (NRT) for smoking reduction (SR) is linked to higher quit attempt rates than SR without NRT. This study aimed to assess the possible mediating roles of confidence in ability to quit, enjoyment of smoking and motivation to quit in this association.

DESIGN

Cross-sectional survey.

MAIN OUTCOME MEASURES

Smokers were asked if they were currently attempting SR, and if they were, whether they were using NRT. Motivation to stop, enjoyment of smoking, confidence in ability to stop, and previous quit attempts, were also assessed.

RESULTS

There was no evidence that confidence in ability to quit or enjoyment of smoking mediated the association between the use of NRT for SR and attempts to quit. Only motivation to stop partially mediated between the use of NRT for SR and attempts to stop (indirect effect: odds ratio 1.08, p < 0.001).

CONCLUSION

Although this study is limited by its cross-sectional design, the findings point towards the possibility that the use of NRT to aid SR may promote attempts to stop through increasing motivation to quit but not by increasing confidence or by reducing enjoyment of smoking. Longitudinal studies are required to draw firmer conclusions about the possible mediating effects of motivation to quit.

Smoking reduction at midlife and lifetime mortality risk in men: a prospective cohort study

Previous studies have not shown a survival advantage for smoking reduction. The authors assessed survival and life expectancy according to changes in smoking intensity in a cohort of Israeli working men. Baseline smokers recruited in 1963 were reassessed in 1965 (n = 4,633; mean age, 51 years) and followed up prospectively for mortality through 2005. Smoking intensity at both time points was self-reported and categorized as none, 1-10, 11-20, and ≥21 cigarettes per day. Change between smoking categories was noted, and participants were classified as increased (8%), maintained (65%), reduced (17%), or quit (10%) smoking. During a median follow-up of 26 (quartiles 1-3: 16-35) years, 87% of participants died. Changes in intensity were associated with survival. In multivariable-adjusted models, the hazard ratios for mortality were 1.14 (95% confidence interval (CI): 0.99, 1.32) among increasers, 0.85 (95% CI: 0.77, 0.95) among reducers, and 0.78 (95% CI: 0.69, 0.89) among quitters, compared with maintainers. Inversely, the adjusted odds ratios of surviving to age 80 years were 0.77 (95% CI: 0.60, 0.98), 1.22 (95% CI: 1.01, 1.47), and 1.33 (95% CI: 1.07, 1.66), respectively. The survival benefit associated with smoking reduction was mostly evident among heavy smokers and for cardiovascular disease mortality. These results suggest that decreasing smoking intensity should be considered as a risk-reduction strategy for heavy smokers who cannot quit abruptly.

Comparing an immediate cessation versus reduction approach to smokeless tobacco cessation

INTRODUCTION

Relatively few studies have investigated pharmacological or behavioral treatment of smokeless tobacco (ST) users who do not have immediate quit plans. In this study, we compared a reduction treatment approach with an immediate cessation approach in a population of ST users who reported no immediate plans to quit.

METHODS

Subjects randomly assigned to the immediate cessation condition set a quit date soon after enrollment and were offered 2 weeks of nicotine patch therapy to help in their cessation efforts. Subjects assigned to the ST reduction group were provided with their choice of either 4 mg nicotine lozenge or ST brand switching to help them reduce their ST use or levels of nicotine exposure, respectively. Quit date was 6 weeks after the onset of treatment. Follow-up was at 12 weeks and 26 weeks postenrollment and 26 weeks postquit.

RESULTS

Both 7-day point prevalence abstinence and prolonged abstinence rates following the quit date were significantly higher in the immediate cessation group versus the reduction group at 12 and 26 weeks (all p values ≤ .04) and for prolonged abstinence at 6 months postquit (p = .002). Significant reductions in ST use among nonquitters were observed for both groups (p < .0001) with no differences between groups.

CONCLUSION

Our study demonstrated that immediate cessation with an established quit date resulted in greater cessation success than a gradual reduction approach among ST users who do not have an immediate quit plan but are motivated to quit.

A lack of association between severity of nicotine withdrawal and individual differences in compensatory nicotine self-administration in rats

RATIONALE

Compensatory smoking may represent an adverse consequence of smoking reduction or the use of reduced-nicotine tobacco products. Factors contributing to individual variability in compensation are poorly understood.

OBJECTIVE

The objective of this study was to examine whether severity of nicotine withdrawal as measured by elevated intracranial self-stimulation (ICSS) thresholds is related to individual differences in compensatory nicotine self-administration (NSA) following unit dose reduction.

METHODS

Rats were trained for ICSS and NSA (0.06 mg/kg per infusion). After stabilization, effects of reducing the nicotine unit dose to 0.03 mg/kg per infusion were examined. Following reacquisition of NSA (0.06 mg/kg per infusion), effects of antagonist-precipitated withdrawal and saline extinction (spontaneous withdrawal) were examined.

RESULTS

Reducing the NSA unit dose produced partial compensation as indicated by the increased infusion rates, but a 35% mean decrease in daily nicotine intake. The magnitude of compensation varied considerably among rats. Dose reduction did not elicit withdrawal in rats as a group, although there were substantial increases in ICSS thresholds in some animals. Intracranial self-stimulation thresholds were consistently elevated during precipitated and spontaneous withdrawal, confirming that rats were nicotine-dependent. Individual differences in compensation were not correlated with changes in ICSS thresholds during dose reduction, precipitated withdrawal, or spontaneous withdrawal. In a secondary analysis, greater precipitated withdrawal severity predicted greater initial nicotine seeking during extinction.

CONCLUSIONS

Severity of nicotine withdrawal was not related to the degree of compensation in this protocol. These data do not support a role for nicotine withdrawal in individual differences in compensation during reduced nicotine exposure, but do suggest that withdrawal may contribute to nicotine seeking during early abstinence.

The ratio of a urinary tobacco-specific lung carcinogen metabolite to cotinine is significantly higher in passive than in active smokers

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol plus its glucuronides (total NNAL), metabolites of the lung carcinogen NNK, and total cotinine, metabolites of nicotine, are biomarkers of active and passive cigarette smoking. We calculated the total NNAL:total cotinine (×10(3)) ratio in 408 passive (infants, children, and adults) and 1088 active smokers. The weighted averages were 0.73 (95% confidence interval 0.71, 0.76) for passive smokers and 0.07 (0.06, 0.08) for active smokers (p < 0.0001). These results demonstrate that cotinine measurements may underestimate exposure of passive smokers to the lung carcinogen NNK in second-hand cigarette smoke. The total NNAL:total cotinine (×10(3)) ratio may provide an improved biomarker for evaluating the health effects of passive smoking.

Do smoking reduction interventions promote cessation in smokers not ready to quit?

BACKGROUND

Limited treatment options exist for smokers who are not ready to make a quit attempt. Smoking reduction may be a viable treatment approach if proven to increase the rates of long-term abstinence from smoking.

METHOD

A systematic review of randomized, controlled trials that tested smoking-reduction interventions (pharmacological, behavioral, or both combined) among smokers who were not ready to make a quit attempt (immediately or in the next month) was conducted to assess the efficacy of these strategies in promoting future smoking abstinence. The primary outcome was the 7-day point-prevalence smoking abstinence at longest follow-up (≥6months). Ten trials were included; six tested pharmacologic interventions, one evaluated a behavioral intervention, and three evaluated combined interventions.

RESULTS

Pharmacologic (2732 participants; OR 2.33, 95% CI 1.43 to 3.79) and combined (638 participants; OR 2.14, 95% CI: 1.28 to 3.60) smoking-reduction interventions significantly increased long-term abstinence from smoking. Insufficient evidence was available on the efficacy of behavioral smoking-reduction interventions (320 participants; OR 1.49, 95% CI 0.56 to 3.93).

CONCLUSIONS

Further research to evaluate the efficacy of smoking reduction should have cessation as an endpoint, focus on clarity and consistency in patient selection, and identify the mechanism through which nicotine replacement therapy assisted smoking reduction in increasing abstinence rates.

Relationship between smoking reduction and cessation among light smokers

INTRODUCTION

To determine the smoking reduction patterns of light smokers (≤ 10 CPD) and whether reduction predicts future cessation.

METHODS

Study is a secondary analysis of data that were derived from a 2 × 2 randomized study that assessed the efficacy of nicotine gum (vs. placebo) and counseling (motivational interviewing vs. health education) for smoking cessation among 755 light smokers. Participants were categorized into three groups based on self-reported CPD smoked at time of study enrollment compared with CPD smoked a year prior to enrollment. That is, (a) those who reduced number of cigarettes per day (CPD), (b) those who smoked the same number of CPD, and (c) those who increased their number of CPD. Sociodemographic and smoking characteristics were assessed at enrollment as well as cotinine-verified 7-day smoking abstinence rates at the Week 26 follow-up assessment. A stepwise logistic regression model to predict the probability abstinence at 26-week follow-up was also performed.

RESULTS

Compared with a year prior to enrollment, 43.7% of participants reduced, 35.2% smoked the same, and 21.2% increased their CPD. Compared with those who smoked the same or increased their CPD, those who had reduced their CPD were older, more likely to be males, smoked fewer CPD at enrollment, initiated smoking at a younger age, and less likely to be nicotine dependent. Adjusted logistic regression showed that those who had reduced their smoking prior to enrollment were more likely to quit at Week 26 (odds ratio [OR] = 1.77; 95% CI = 1.062-2.957; p = .029).

DISCUSSION

Findings suggest that reducing number of CPD smoked prior to enrolling in a clinical trial is a positive predictor of abstinence. Therefore, encouraging smoking reduction prior to attempting cessation may enhance cessation outcomes for light smokers.

Failure to treat tobacco use in mental health and addiction treatment settings: a form of harm reduction?

In mental health and addiction treatment settings, failure to treat tobacco dependence has been rationalized by some as a clinical approach to harm reduction. That is, tobacco use is viewed as a less harmful alternative to alcohol or illicit drug use and/or other self-harm behaviors. This paper examines the impact of providers' failure to treat tobacco use on patients' alcohol and illicit drug use and associated high-risk behaviors. The weight of the evidence in the literature indicates: (1) tobacco use is a leading cause of death in patients with psychiatric illness or addictive disorders; (2) tobacco use is associated with worsened substance abuse treatment outcomes, whereas treatment of tobacco dependence supports long-term sobriety; (3) tobacco use is associated with increased (not decreased) depressive symptoms and suicidal risk behavior; (4) tobacco use adversely impacts psychiatric treatment; (5) tobacco use is a lethal and ineffective long-term coping strategy for managing stress, and (6) treatment of tobacco use does not harm mental health recovery. Failure to treat tobacco dependence in mental health and addiction treatment settings is not consistent with a harm reduction model. In contrast, emerging evidence indicates treatment of tobacco dependence may even improve addiction treatment and mental health outcomes. Providers in mental health and addiction treatment settings have an ethical duty to intervene on patients' tobacco use and provide available evidence-based treatments.

C-reactive protein as a predictor of disease in smokers and former smokers: a review

BACKGROUND

Cigarette smoking is a classical and a major risk factor in the development of several diseases with an inflammatory component, including cardiovascular disease and chronic obstructive pulmonary disease. Improvements in assays for protein markers of inflammation have led to many studies on these factors and their roles in disease.

AIMS

C-reactive protein (CRP) is one such marker and this review focuses on the evidence for using CRP as a diagnostic marker and how levels of this protein are modified according to the smoking status of the patient, both in terms of the current amount of cigarettes smoked and how CRP levels change following smoking cessation.

CONCLUSIONS

Assay of CRP levels may be useful in monitoring disease progression and determining risk of future cardiovascular complications. However, as this marker is also an indicator of acute inflammation and challenges to the immune system, some caution must be exercised in interpreting the available data on CRP levels in patients with different chronic comorbidities.

Correlates of individual differences in compensatory nicotine self-administration in rats following a decrease in nicotine unit dose

RATIONALE

The ability of tobacco harm reduction strategies to produce significant reductions in toxin exposure is limited by compensatory increases in smoking behavior. Characterizing factors contributing to the marked individual variability in compensation may be useful for understanding this phenomenon and assessing the feasibility of harm reduction interventions.

OBJECTIVE

The objective of the study was to use an animal model of human compensatory smoking that involves a decrease in unit dose supporting nicotine self-administration (NSA) to examine potential contributors to individual differences in compensation.

METHODS

Rats were trained for NSA during daily 23-h sessions at a unit dose of 0.06 mg/kg/inf until responding was stable. The unit dose was then reduced to 0.03 mg/kg/inf for at least 10 sessions. Following reacquisition of NSA at the training dose and extinction, single-dose nicotine pharmacokinetic parameters were determined.

RESULTS

Decreases in nicotine intake following dose reduction were proportionally less than the decrease in unit dose, indicating partial compensation. Compensatory increases in infusion rates were observed across the course of the 23-h sessions. The magnitude of compensation differed considerably between rats. Rats exhibiting the highest baseline infusion rates exhibited the lowest levels of compensation. Nicotine pharmacokinetic parameters were not significantly correlated with compensation. Infusion rates immediately returned to pre-reduction levels when baseline conditions were restored.

CONCLUSIONS

These findings provide initial insights into correlates of individual differences in compensation following a reduction in nicotine unit dose. The present assay may be useful for characterizing mechanisms and potential consequences of the marked individual differences in compensatory smoking observed in humans.

Developing the science base for reducing tobacco harm

The University of Minnesota Transdisciplinary Tobacco Use Research Center has been examining the multiple dimensions and the scientific evidence required to determine the feasibility of tobacco harm reduction as a means to reduce tobacco-related mortality and morbidity. Because of the complexity associated with exploring this area, an interdisciplinary approach is necessary. The research components that have been of particular focus at our center include (a) developing and validating biomarkers of tobacco-related exposure and toxicity, (b) developing animal models and designing studies with humans to assess a variety of smoking reduction approaches and potential reduced exposure products, and (c) determining individual differences in response to these interventions and products. A description of the ongoing activities and challenges in these areas is provided, along with projected directions for the future.

Similar exposure to a tobacco-specific carcinogen in smokeless tobacco users and cigarette smokers

Smokeless tobacco has been proposed as a reduced risk substitute for smoking, but no large studies have investigated exposure to the powerful carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in smokeless tobacco users versus smokers. The purpose of this study was to carry out such a comparison. Levels of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and its glucuronides (total NNAL), a biomarker of NNK exposure, and cotinine, a biomarker of nicotine exposure, were quantified in the urine of 420 smokers and 182 smokeless tobacco users who were participants in studies designed to reduce their use of these products. The measurements were taken at baseline, before intervention. Levels of total NNAL per milliliter of urine were significantly higher in smokeless tobacco users than in smokers (P < 0.0001). When adjusted for age and gender, levels of total NNAL per milligram of creatinine were also significantly higher in smokeless tobacco users than in smokers (P < 0.001). Levels of cotinine per milliliter of urine and per milligram of creatinine were significantly higher in smokeless tobacco users than in smokers (P < 0.001). These results show similar exposures to the potent tobacco-specific carcinogen NNK in smokeless tobacco users and smokers. These findings do not support the use of smokeless tobacco as a safe substitute for smoking.

Interventions to reduce harm from continued tobacco use

BACKGROUND

It may be reasonable to try to reduce the harm from continued smoking 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. The interventions evaluated in controlled trials have predominantly attempted to reduce the number of cigarettes smoked.

OBJECTIVES

To assess the effect of interventions intended to reduce the harm from smoking on the following: biomarkers of damage caused by tobacco, biomarkers of tobacco exposure, number of cigarettes smoked, quitting, and long-term health status.

SEARCH STRATEGY

We searched the Cochrane Tobacco Addiction Group Specialised Register using free text and MeSH terms for harm reduction, smoking reduction and cigarette reduction. The initial search was in March 2006, updated in March 2007.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials of interventions in tobacco users to reduce amount smoked, or to reduce harm from smoking by means other than cessation. Outcomes were change in cigarette consumption, markers of cigarette exposure 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 pooled trials with similar interventions and outcomes using a fixed-effect model. Other studies were summarised narratively.

MAIN RESULTS

The 13 included trials all evaluated interventions to help smokers cut down the amount smoked. Self-reported reduction in cigarettes per day (CPD) was validated by reduction in carbon monoxide (CO) levels. Most trials tested nicotine replacement therapy (NRT) to assist reduction. No eligible studies evaluated the use of potentially reduced-exposure products. In a pooled analysis of eight trials, NRT significantly increased the odds of reducing CPD by 50% or more for people using nicotine gum or inhaler or a choice of product compared to placebo (n=3273, odds ratio [OR] 2.02, 95% confidence interval [CI] 1.55 to 2.62). Where average changes from baseline were compared for different measures, CO and cotinine consistently showed smaller reductions than CPD. Whilst the effect for NRT was significant, small numbers of people in either treatment or control group successfully sustained a reduction of 50% or more. Use of NRT also significantly increased the odds of quitting (OR 1.90, 95% CI 1.46 to 2.47). One trial of bupropion failed to detect an effect on reduction or cessation. Four trials of different types of advice and instructions on reducing CPD did not provide clear evidence.

AUTHORS' CONCLUSIONS

There is insufficient evidence about long-term benefit to give firm support the use of interventions intended to help smokers reduce but not quit tobacco use. Some people who do not wish to quit can be helped to cut down the number of cigarettes smoked and reduce their carbon monoxide levels by using nicotine gum or nicotine inhaler. Because the long-term health benefit of a reduction in smoking rate is unclear this application of NRT is more appropriately used as a precursor to quitting.