Interventions for preventing weight gain after smoking cessation

Opioid antagonists for smoking cessation

BACKGROUND

The reinforcing properties of nicotine may be mediated through release of various neurotransmitters both centrally and systemically. People who smoke report positive effects such as pleasure, arousal, and relaxation as well as relief of negative affect, tension, and anxiety. Opioid (narcotic) antagonists are of particular interest to investigators as potential agents to attenuate the rewarding effects of cigarette smoking.

OBJECTIVES

To evaluate the efficacy of opioid antagonists in promoting long-term smoking cessation. The drugs include naloxone and the longer-acting opioid antagonist naltrexone.

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group Specialised Register for trials of naloxone, naltrexone and other opioid antagonists and conducted an additional search of MEDLINE using 'Narcotic antagonists' and smoking terms in April 2013. We also contacted investigators, when possible, for information on unpublished studies.

SELECTION CRITERIA

We considered randomised controlled trials comparing opioid antagonists to placebo or an alternative therapeutic control for smoking cessation. We included in the meta-analysis only those trials which reported data on abstinence for a minimum of six months. We also reviewed, for descriptive purposes, results from short-term laboratory-based studies of opioid antagonists designed to evaluate psycho-biological mediating variables associated with nicotine dependence.

DATA COLLECTION AND ANALYSIS

We extracted data in duplicate on the study population, the nature of the drug therapy, the outcome measures, method of randomisation, and completeness of follow-up. The main outcome measure was abstinence from smoking after at least six months follow-up in patients smoking at baseline. Abstinence at end of treatment was a secondary outcome. We extracted cotinine- or carbon monoxide-verified abstinence where available. Where appropriate, we performed meta-analysis, pooling risk ratios using a Mantel-Haenszel fixed-effect model.

MAIN RESULTS

Eight trials of naltrexone met inclusion criteria for meta-analysis of long-term cessation. One trial used a factorial design so five trials compared naltrexone versus placebo and four trials compared naltrexone plus nicotine replacement therapy (NRT) versus placebo plus NRT. Results from 250 participants in one long-term trial remain unpublished. No significant difference was detected between naltrexone and placebo (risk ratio (RR) 1.00; 95% confidence interval (CI) 0.66 to 1.51, 445 participants), or between naltrexone and placebo as an adjunct to NRT (RR 0.95; 95% CI 0.70 to 1.30, 768 participants). The estimate was similar when all eight trials were pooled (RR 0.97; 95% CI 0.76 to 1.24, 1213 participants). In a secondary analysis of abstinence at end of treatment, there was also no evidence of any early treatment effect, (RR 1.03; 95% CI 0.88 to 1.22, 1213 participants). No trials of naloxone or buprenorphine reported abstinence outcomes.

AUTHORS' CONCLUSIONS

Based on data from eight trials and over 1200 individuals, there was no evidence of an effect of naltrexone alone or as an adjunct to NRT on long-term smoking abstinence, with a point estimate strongly suggesting no effect and confidence intervals that make a clinically important effect of treatment unlikely. Although further trials might narrow the confidence intervals they are unlikely to be a good use of resources.

Is a combination of varenicline and nicotine patch more effective in helping smokers quit than varenicline alone? A randomised controlled trial

BACKGROUND

Nicotine replacement therapy (NRT) and varenicline are both effective in helping smokers quit. There is growing interest in combining the two treatments to improve treatment outcomes, but no experimental data exist on whether this is efficacious. This double-blind randomised controlled trial was designed to evaluate whether adding nicotine patches to varenicline improves withdrawal relief and short-term abstinence rates.

METHODS

117 participants seeking help to stop smoking were randomly allocated to varenicline plus placebo patch or varenicline plus nicotine patch (15 mg/16 hour). Varenicline use commenced one week prior to the target quit date (TQD), patch use started on the TQD. Ratings of urges to smoke and cigarette withdrawal symptoms were collected weekly over 4 weeks post-TQD. Medication use and smoking status were established at 1, 4 and 12 weeks. Participants lost to follow-up were included as continuing smokers.

RESULTS

92% of participants used both medications during the first week after the TQD. The combination treatment generated no increase in nausea or other adverse effects. It had no overall effect on urges to smoke or on other withdrawal symptoms. The combination treatment did not improve biochemically validated abstinence rates at 1 week and 4 weeks post-TQD (69% vs 59%, p=0.28 and 60% vs 59%, p=0.91, in the nicotine patch and placebo patch arm, respectively), or self reported abstinence rates at 12 weeks (36% vs. 29%, p=0.39, NS).

CONCLUSIONS

The efficacy of varenicline was not enhanced by the addition of nicotine patches, although further trials would be useful to exclude the possibility of type II error.

TRIAL REGISTRATION

Clinicaltrials.gov

REGISTRATION NUMBER

NCT01184664.

Naltrexone reduction of long-term smoking cessation weight gain in women but not men: a randomized controlled trial

BACKGROUND

The opioid antagonist naltrexone has shown promise to reduce weight gain during active treatment, but longer-term studies have not been conducted. The goal was to examine effects of naltrexone on weight gain over long-term follow-up in men and women who quit smoking.

METHODS

Weight was examined at baseline and 6- and 12-month follow-up in the two largest randomized, double-blind, placebo-controlled trials of naltrexone in nicotine dependence. For 6-12 weeks after the quit date, participants were randomly assigned to receive naltrexone or placebo. Behavioral counseling and open-label nicotine patch were also included for the first 4-6 weeks. Of the 700 participants in the combined intent-to-treat sample, there were 159 (77 women) biochemically verified abstinent smokers at 6 months, and 115 (57 women) of them remained abstinent at 12 months. Changes in weight (in kilograms or in percentage) and body mass index from baseline to the follow-ups were assessed for these participants.

RESULTS

Weight gain was significantly lower for women treated with naltrexone compared with placebo (6 months, 3.3 vs. 5.5 kg; 12 months, 5.9 vs. 7.4 kg, respectively). Increases in body mass index and percentage body weight gain were also significantly lower in women treated with naltrexone versus placebo. These effects were not observed in men.

CONCLUSION

The results provide evidence for naltrexone as the first pharmacotherapy to reduce postsmoking cessation weight gain among women.

An updated algorithm for choosing among smoking cessation treatments

Although meta-analyses have documented the efficacy of treatments for smoking cessation, and guidelines have outlined treatment elements, few algorithms for choosing among treatments have been described. The current algorithm updates the author's prior algorithm. The major decisions in the algorithm are (a) use a motivational treatment if the smoker is not currently interested in quitting, (b) assess factors that influence choice of treatment, (c) consider both gradual and abrupt cessation, (d) use combined patch+gum/inhaler/lozenge or varenicline as first line medications, (e) use individual, group, Internet, and phone counseling as first line psychosocial treatments, and (f) continue treatment after a lapse or relapse. Further research is needed to determine whether algorithms improve treatment outcomes.

The acute effects of physical activity on cigarette cravings: systematic review and meta-analysis with individual participant data

AIMS

To conduct an updated systematic review and the first meta-analysis of experimental trials investigating the acute effects of short bouts of physical activity (PA) on strength of desire (SoD) and desire to smoke (DtS) using individual participant data (IPD).

METHODS

A systematic review of literature and IPD meta-analyses included trials assessing the acute effects of shorts bouts of PA on SoD and DtS among temporarily abstaining smokers not using pharmaceutical aids for smoking cessation. Authors of eligible studies were contacted and raw IPD were obtained. Two-stage and one-stage IPD random-effects meta-analyses were conducted. Participants engaging in PA were compared against control participants, using post-intervention SoD and DtS with baseline adjustments.

RESULTS

A two-stage IPD meta-analysis assessing effects of PA on SoD yielded an average standardized mean difference (SMD) between PA and control conditions (across 15 primary studies) of -1.91 [95% confidence interval (CI): -2.59 to -1.22]. A two-stage IPD meta-analysis assessing effects of PA on DtS yielded an average SMD between PA and control conditions (across 17 primary studies) of -2.03 (95% CI: -2.60 to -1.46). Additional meta-analyses, including those using a one-stage model, those including only parallel arm studies and meta-analyses comparing only moderate exercise against a control condition, showed significant craving reduction following PA. Despite a high degree of between-study heterogeneity, effects sizes of all primary studies were in the same direction, with PA showing a greater reduction in cravings compared with controls.

CONCLUSIONS

There is strong evidence that physical activity acutely reduces cigarette craving.

Nicotinic regulation of energy homeostasis

INTRODUCTION

The ability of nicotine, the primary psychoactive substance in tobacco smoke, to regulate appetite and body weight is one of the factors cited by smokers that prevents them from quitting and is the primary reason for smoking initiation in teenage girls. The regulation of feeding and metabolism by nicotine is complex, and recent studies have begun to identify nicotinic acetylcholine receptor (nAChR) subtypes and circuits or cell types involved in this regulation.

DISCUSSION

We will briefly describe the primary anatomical and functional features of the input, output, and central integration structures of the neuroendocrine systems that regulate energy homeostasis. Then, we will describe the nAChR subtypes expressed in these structures in mammals to identify the possible molecular targets for nicotine. Finally, we will review the effects of nicotine and its withdrawal on feeding and energy metabolism and attribute them to potential central and peripheral cellular targets.

YMCA commit to quit: randomized trial outcomes

BACKGROUND

Vigorous-intensity exercise has been shown to aid in smoking cessation, especially among women. In a previous trial, cognitive behavioral therapy (CBT) for smoking cessation plus regular vigorous aerobic exercise enhanced cessation rates, improved exercise capacity, and reduced weight gain compared to CBT plus equal contact time.

PURPOSE

This study examined the effectiveness of this program adapted for and implemented in the YMCAs.

DESIGN

An RCT comparing CBT + Exercise (Exercise) to CBT + Contact Control (Control).

SETTING/PARTICIPANTS

Apparently healthy female smokers were recruited to four local YMCAs.

INTERVENTION

YMCA staff members were trained to lead the manualized CBT smoking-cessation intervention and a standardized YMCA exercise program.

MAIN OUTCOME MEASURES

Seven-day point prevalence and continuous abstinence.

RESULTS

Participants (330 women, mean age=44 years) were randomized to the Exercise (n=166) or Control (n=164) group. Results revealed no differences in 7-day point prevalence (29.5% vs 29.9%) nor continuous abstinence (13.9% vs 14.0%) between the Exercise and Control groups, respectively, at end of treatment or at the 3-, 6-, and 12-month follow-up. An examination of the relationship between exercise dose and quit status at end of treatment revealed that over 12 weeks, the odds of being quit (7-day point prevalence) grew by 4.5% for each additional aerobic exercise session (OR=1.05, 95% CI=1.01, 1.08) and by 7.7% for each additional resistance training session (OR=1.08, 95% CI=1.02, 1.14). Analyses were conducted between August 19, 2010, and December 16, 2011.

CONCLUSIONS

No differences were seen between groups in smoking outcomes. The association between greater exercise participation and higher odds of quitting within the exercise condition suggests that the lack of between-group differences might be a result of poor compliance with the exercise program.

TRIAL REGISTRATION

This study is registered at clinicaltrials.govNCT01615380.

Weight gain in smokers after quitting cigarettes: meta-analysis

OBJECTIVE

To describe weight gain and its variation in smokers who achieve prolonged abstinence for up to 12 months and who quit without treatment or use drugs to assist cessation.

DESIGN

Meta-analysis.

DATA SOURCES

We searched the Central Register of Controlled Trials (CENTRAL) and trials listed in Cochrane reviews of smoking cessation interventions (nicotine replacement therapy, nicotinic partial agonists, antidepressants, and exercise) for randomised trials of first line treatments (nicotine replacement therapy, bupropion, and varenicline) and exercise that reported weight change. We also searched CENTRAL for trials of interventions for weight gain after cessation.

REVIEW METHODS

Trials were included if they recorded weight change from baseline to follow-up in abstinent smokers. We used a random effects inverse variance model to calculate the mean and 95% confidence intervals and the mean of the standard deviation for weight change from baseline to one, two, three, six, and 12 months after quitting. We explored subgroup differences using random effects meta-regression.

RESULTS

62 studies were included. In untreated quitters, mean weight gain was 1.12 kg (95% confidence interval 0.76 to 1.47), 2.26 kg (1.98 to 2.54), 2.85 kg (2.42 to 3.28), 4.23 kg (3.69 to 4.77), and 4.67 kg (3.96 to 5.38) at one, two, three, six, and 12 months after quitting, respectively. Using the means and weighted standard deviations, we calculated that at 12 months after cessation, 16%, 37%, 34%, and 13% of untreated quitters lost weight, and gained less than 5 kg, gained 5-10 kg, and gained more than 10 kg, respectively. Estimates of weight gain were similar for people using different pharmacotherapies to support cessation. Estimates were also similar between people especially concerned about weight gain and those not concerned.

CONCLUSION

Smoking cessation is associated with a mean increase of 4-5 kg in body weight after 12 months of abstinence, and most weight gain occurs within three months of quitting. Variation in weight change is large, with about 16% of quitters losing weight and 13% gaining more than 10 kg.