-
The Cochrane Database of Systematic... May 2013Smoking is the leading preventable cause of illness and premature death worldwide. Some medications have been proven to help people to quit, with three licensed for this... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Smoking is the leading preventable cause of illness and premature death worldwide. Some medications have been proven to help people to quit, with three licensed for this purpose in Europe and the USA: nicotine replacement therapy (NRT), bupropion, and varenicline. Cytisine (a treatment pharmacologically similar to varenicline) is also licensed for use in Russia and some of the former socialist economy countries. Other therapies, including nortriptyline, have also been tested for effectiveness.
OBJECTIVES
How do NRT, bupropion and varenicline compare with placebo and with each other in achieving long-term abstinence (six months or longer)? How do the remaining treatments compare with placebo in achieving long-term abstinence? How do the risks of adverse and serious adverse events (SAEs) compare between the treatments, and are there instances where the harms may outweigh the benefits?
METHODS
The overview is restricted to Cochrane reviews, all of which include randomised trials. Participants are usually adult smokers, but we exclude reviews of smoking cessation for pregnant women and in particular disease groups or specific settings. We cover nicotine replacement therapy (NRT), antidepressants (bupropion and nortriptyline), nicotine receptor partial agonists (varenicline and cytisine), anxiolytics, selective type 1 cannabinoid receptor antagonists (rimonabant), clonidine, lobeline, dianicline, mecamylamine, Nicobrevin, opioid antagonists, nicotine vaccines, and silver acetate. Our outcome for benefit is continuous or prolonged abstinence at least six months from the start of treatment. Our outcome for harms is the incidence of serious adverse events associated with each of the treatments. We searched the Cochrane Database of Systematic Reviews (CDSR) in The Cochrane Library, for any reviews with 'smoking' in the title, abstract or keyword fields. The last search was conducted in November 2012. We assessed methodological quality using a revised version of the AMSTAR scale. For NRT, bupropion and varenicline we conducted network meta-analyses, comparing each with the others and with placebo for benefit, and varenicline and bupropion for risks of serious adverse events.
MAIN RESULTS
We identified 12 treatment-specific reviews. The analyses covered 267 studies, involving 101,804 participants. Both NRT and bupropion were superior to placebo (odds ratios (OR) 1.84; 95% credible interval (CredI) 1.71 to 1.99, and 1.82; 95% CredI 1.60 to 2.06 respectively). Varenicline increased the odds of quitting compared with placebo (OR 2.88; 95% CredI 2.40 to 3.47). Head-to-head comparisons between bupropion and NRT showed equal efficacy (OR 0.99; 95% CredI 0.86 to 1.13). Varenicline was superior to single forms of NRT (OR 1.57; 95% CredI 1.29 to 1.91), and to bupropion (OR 1.59; 95% CredI 1.29 to 1.96). Varenicline was more effective than nicotine patch (OR 1.51; 95% CredI 1.22 to 1.87), than nicotine gum (OR 1.72; 95% CredI 1.38 to 2.13), and than 'other' NRT (inhaler, spray, tablets, lozenges; OR 1.42; 95% CredI 1.12 to 1.79), but was not more effective than combination NRT (OR 1.06; 95% CredI 0.75 to 1.48). Combination NRT also outperformed single formulations. The four categories of NRT performed similarly against each other, apart from 'other' NRT, which was marginally more effective than NRT gum (OR 1.21; 95% CredI 1.01 to 1.46). Cytisine (a nicotine receptor partial agonist) returned positive findings (risk ratio (RR) 3.98; 95% CI 2.01 to 7.87), without significant adverse events or SAEs. Across the 82 included and excluded bupropion trials, our estimate of six seizures in the bupropion arms versus none in the placebo arms was lower than the expected rate (1:1000), at about 1:1500. SAE meta-analysis of the bupropion studies demonstrated no excess of neuropsychiatric (RR 0.88; 95% CI 0.31 to 2.50) or cardiovascular events (RR 0.77; 95% CI 0.37 to 1.59). SAE meta-analysis of 14 varenicline trials found no difference between the varenicline and placebo arms (RR 1.06; 95% CI 0.72 to 1.55), and subgroup analyses detected no significant excess of neuropsychiatric events (RR 0.53; 95% CI 0.17 to 1.67), or of cardiac events (RR 1.26; 95% CI 0.62 to 2.56). Nortriptyline increased the chances of quitting (RR 2.03; 95% CI 1.48 to 2.78). Neither nortriptyline nor bupropion were shown to enhance the effect of NRT compared with NRT alone. Clonidine increased the chances of quitting (RR 1.63; 95% CI 1.22 to 2.18), but this was offset by a dose-dependent rise in adverse events. Mecamylamine in combination with NRT may increase the chances of quitting, but the current evidence is inconclusive. Other treatments failed to demonstrate a benefit compared with placebo. Nicotine vaccines are not yet licensed for use as an aid to smoking cessation or relapse prevention. Nicobrevin's UK license is now revoked, and the manufacturers of rimonabant, taranabant and dianicline are no longer supporting the development or testing of these treatments.
AUTHORS' CONCLUSIONS
NRT, bupropion, varenicline and cytisine have been shown to improve the chances of quitting. Combination NRT and varenicline are equally effective as quitting aids. Nortriptyline also improves the chances of quitting. On current evidence, none of the treatments appear to have an incidence of adverse events that would mitigate their use. Further research is warranted into the safety of varenicline and into cytisine's potential as an effective and affordable treatment, but not into the efficacy and safety of NRT.
Topics: Adult; Alkaloids; Antidepressive Agents, Second-Generation; Azocines; Benzazepines; Bupropion; Humans; Nicotinic Agonists; Nortriptyline; Quinolizines; Quinoxalines; Randomized Controlled Trials as Topic; Review Literature as Topic; Smoking; Smoking Cessation; Tobacco Use Cessation Devices; Varenicline
PubMed: 23728690
DOI: 10.1002/14651858.CD009329.pub2 -
Nicotine & Tobacco Research : Official... Jan 2016Conduct a systematic review and meta-analysis on the effectiveness and safety of varenicline in smokeless tobacco (SLT) cessation. (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
Conduct a systematic review and meta-analysis on the effectiveness and safety of varenicline in smokeless tobacco (SLT) cessation.
METHODS
PubMed, EMBASE, clinicaltrials.gov, and the Cochrane Registry were searched up to February 1, 2014, for randomized clinical trials (RCTs) comparing varenicline to placebo. Random effects Mantel-Haenszel summary relative risks (RRs), risk difference (RD), and 95% CIs were used for analysis and reporting of outcomes. Primary and secondary outcomes were the 7-day point prevalence of SLT abstinence at the end of 12 and 26 weeks, respectively. Adverse events reported include nausea, sleep disturbance, and mood disorders.
RESULTS
Three published RCTs involving 744 SLT users with a mean age of 39.7 years, of which greater than 88% were males, were randomized to varenicline (n = 370) and placebo (n = 374). Subjects in the varenicline arm had a significantly higher 7-day point prevalence of SLT abstinence at 12 weeks (48% vs. 33%; RR = 1.45, 95% CI = 1.22-1.72, p < .0001, I2 = 0%; RD = 13%, 95% CI = 4%-23%, p = .008) but not at 26 weeks (49% vs. 39%; RR = 1.38, 95% CI = 0.93-2.03, p = .11, I2 = 51%). There were no statistically significant differences in the incidences of adverse events between the 2 arms but interpretation is limited by high heterogeneity.
CONCLUSION
This pooled analysis suggests that varenicline is effective in achieving a 7-day point prevalence of SLT abstinence at 12 weeks but showed that this effect was not sustained at 26 weeks.
Topics: Humans; Nicotinic Agonists; Product Surveillance, Postmarketing; Suicide; Tobacco Use Cessation; Varenicline
PubMed: 25646351
DOI: 10.1093/ntr/ntv010 -
Nicotine & Tobacco Research : Official... Jul 2019Smoking in pregnancy is a substantial public health issue, but, apart from nicotine replacement therapy (NRT), pharmacological therapies are not generally used to... (Meta-Analysis)
Meta-Analysis
INTRODUCTION
Smoking in pregnancy is a substantial public health issue, but, apart from nicotine replacement therapy (NRT), pharmacological therapies are not generally used to promote cessation. Bupropion and varenicline are effective cessation methods in nonpregnant smokers and this systematic review investigates their safety in pregnancy.
METHODS
We searched MEDLINE, EMBASE, CINAHL, and PsychINFO databases for studies of any design reporting pregnancy outcomes after bupropion or varenicline exposure. We included studies of bupropion used for smoking cessation, depression, or where the indication was unspecified. Depending on study design, quality was assessed using the Newcastle-Ottawa Scale or Cochrane Risk of Bias Tool. Most findings are reported narratively but meta-analyses were used to produce pooled estimates for the proportion of live births with congenital malformations and of the mean birthweight and gestational age at delivery following bupropion exposure.
RESULTS
In total, 18 studies were included: 2 randomized controlled trials, 11 cohorts, 2 case- control studies, and 3 case reports. Study quality was variable. Gestational safety outcomes were reported in 14 bupropion and 4 varenicline studies. Meaningful meta-analysis was only possible for bupropion exposure, for which the pooled estimated proportion of congenital malformations amongst live-born infants was 1.0% (95% CI = 0.0%-3.0%, I2 = 80.9%, 4 studies) and the mean birthweight and mean gestational age at delivery was 3305.9 g (95% CI = 3173.2-3438.7 g, I2 = 77.6%, 5 studies) and 39.2 weeks (95% CI = 38.8-39.6 weeks, I2 = 69.9%, 5 studies), respectively.
CONCLUSIONS
There was no strong evidence that either major positive or negative outcomes were associated with gestational use of bupropion or varenicline. PROSPERO registration number CRD42017067064.
IMPLICATIONS
We believe this to be the first systematic review investigating the safety of bupropion and varenicline in pregnancy. Meta-analysis of outcomes following bupropion exposure in pregnancy suggests that there are no major positive or negative impacts on the rate of congenital abnormalities, birthweight, or premature birth. Overall, we found no evidence that either of these treatments might be harmful in pregnancy, and no strong evidence to suggest safety, but available evidence is of poor quality.
Topics: Bupropion; Case-Control Studies; Female; Humans; Nicotinic Agonists; Pregnancy; Pregnancy Complications; Pregnancy Outcome; Smoking; Smoking Cessation; Smoking Cessation Agents; Varenicline
PubMed: 29579233
DOI: 10.1093/ntr/nty055 -
Addiction Biology Aug 2023To evaluate the effectiveness, safety and tolerability of antidepressants in helping smokers quit tobacco dependence, five databases were searched for randomized... (Meta-Analysis)
Meta-Analysis Review
To evaluate the effectiveness, safety and tolerability of antidepressants in helping smokers quit tobacco dependence, five databases were searched for randomized controlled trials (RCT ) on different antidepressant interventions involving smoking cessation in populations (September 2022). The STATA 15.1 software was used to perform network meta-analysis. The Cochrane bias risk tool was used to assess the risk of bias, and CINeMA was used to evaluate the evidence credibility for the effect of different interventions on smoking cessation. In all, 107 RCTs involving 42 744 patients were included. Seven studies were rated as having a low risk of bias. All trials reported 18 interventions and 153 pairwise comparisons were generated. The network meta-analysis showed that compared with placebo, varenicline + bupropion (OR = 3.53, 95% CI [2.34, 5.34]), selegiline + nicotine replacement therapy (NRT) (OR = 3.78, 95% CI [1.20, 11.92]), nortriptyline + NRT (OR = 2.33, 95% CI [1.21, 4.47), nortriptyline (OR = 1.58, 95% CI [1.11,2.26]), naltrexone + bupropion (OR = 3.84, 95% CI [1.39, 10.61]), bupropion + NRT (OR = 2.29, 95% CI [1.87, 2.81]) and bupropion (OR = 1.70, 95% CI [1.53, 1.89]) showed benefits with respect to smoking cessation. In addition, bupropion + NRT showed better effects than bupropion (OR = 1.35, 95% CI [1.12, 1.64]) and NRT (OR = 1.38, 95% CI [1.13, 1.69]) alone. The final cumulative ranking curve showed that varenicline + bupropion was the most likely to be the best intervention. There was moderate- to very-low-certainty evidence that most interventions showed benefits for smoking cessation compared with placebo, including monotherapy and combination therapies. Varenicline + bupropion had a higher probability of being the best intervention for smoking cessation.
Topics: Humans; Smoking Cessation; Bupropion; Varenicline; Nortriptyline; Network Meta-Analysis; Smoking; Tobacco Use Cessation Devices; Antidepressive Agents; Alcoholism
PubMed: 37500482
DOI: 10.1111/adb.13303 -
The Cochrane Database of Systematic... Apr 2021Electronic cigarettes (ECs) are handheld electronic vaping devices which produce an aerosol formed by heating an e-liquid. Some people who smoke use ECs to stop or... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Electronic cigarettes (ECs) are handheld electronic vaping devices which produce an aerosol formed by heating an e-liquid. Some people who smoke use ECs to stop or reduce smoking, but some organizations, advocacy groups and policymakers have discouraged this, citing lack of evidence of efficacy and safety. People who smoke, healthcare providers and regulators want to know if ECs can help people quit and if they are safe to use for this purpose. This is an update of a review first published in 2014.
OBJECTIVES
To examine the effectiveness, tolerability, and safety of using electronic cigarettes (ECs) to help people who smoke achieve long-term smoking abstinence.
SEARCH METHODS
We searched the Cochrane Tobacco Addiction Group's Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and PsycINFO to 1 February 2021, together with reference-checking and contact with study authors.
SELECTION CRITERIA
We included randomized controlled trials (RCTs) and randomized cross-over trials in which people who smoke were randomized to an EC or control condition. We also included uncontrolled intervention studies in which all participants received an EC intervention. To be included, studies had to report abstinence from cigarettes at six months or longer and/or data on adverse events (AEs) or other markers of safety at one week or longer.
DATA COLLECTION AND ANALYSIS
We followed standard Cochrane methods for screening and data extraction. Our primary outcome measures were abstinence from smoking after at least six months follow-up, adverse events (AEs), and serious adverse events (SAEs). Secondary outcomes included changes in carbon monoxide, blood pressure, heart rate, blood oxygen saturation, lung function, and levels of known carcinogens/toxicants. We used a fixed-effect Mantel-Haenszel model to calculate the risk ratio (RR) with a 95% confidence interval (CI) for dichotomous outcomes. For continuous outcomes, we calculated mean differences. Where appropriate, we pooled data from these studies in meta-analyses.
MAIN RESULTS
We included 56 completed studies, representing 12,804 participants, of which 29 were RCTs. Six of the 56 included studies were new to this review update. Of the included studies, we rated five (all contributing to our main comparisons) at low risk of bias overall, 41 at high risk overall (including the 25 non-randomized studies), and the remainder at unclear risk. There was moderate-certainty evidence, limited by imprecision, that quit rates were higher in people randomized to nicotine EC than in those randomized to nicotine replacement therapy (NRT) (risk ratio (RR) 1.69, 95% confidence interval (CI) 1.25 to 2.27; I = 0%; 3 studies, 1498 participants). In absolute terms, this might translate to an additional four successful quitters per 100 (95% CI 2 to 8). There was low-certainty evidence (limited by very serious imprecision) that the rate of occurrence of AEs was similar) (RR 0.98, 95% CI 0.80 to 1.19; I = 0%; 2 studies, 485 participants). SAEs occurred rarely, with no evidence that their frequency differed between nicotine EC and NRT, but very serious imprecision led to low certainty in this finding (RR 1.37, 95% CI 0.77 to 2.41: I = n/a; 2 studies, 727 participants). There was moderate-certainty evidence, again limited by imprecision, that quit rates were higher in people randomized to nicotine EC than to non-nicotine EC (RR 1.70, 95% CI 1.03 to 2.81; I = 0%; 4 studies, 1057 participants). In absolute terms, this might again lead to an additional four successful quitters per 100 (95% CI 0 to 11). These trials mainly used older EC with relatively low nicotine delivery. There was moderate-certainty evidence of no difference in the rate of AEs between these groups (RR 1.01, 95% CI 0.91 to 1.11; I = 0%; 3 studies, 601 participants). There was insufficient evidence to determine whether rates of SAEs differed between groups, due to very serious imprecision (RR 0.60, 95% CI 0.15 to 2.44; I = n/a; 4 studies, 494 participants). Compared to behavioral support only/no support, quit rates were higher for participants randomized to nicotine EC (RR 2.70, 95% CI 1.39 to 5.26; I = 0%; 5 studies, 2561 participants). In absolute terms this represents an increase of seven per 100 (95% CI 2 to 17). However, this finding was of very low certainty, due to issues with imprecision and risk of bias. There was no evidence that the rate of SAEs differed, but some evidence that non-serious AEs were more common in people randomized to nicotine EC (AEs: RR 1.22, 95% CI 1.12 to 1.32; I = 41%, low certainty; 4 studies, 765 participants; SAEs: RR 1.17, 95% CI 0.33 to 4.09; I = 5%; 6 studies, 1011 participants, very low certainty). Data from non-randomized studies were consistent with RCT data. The most commonly reported AEs were throat/mouth irritation, headache, cough, and nausea, which tended to dissipate with continued use. Very few studies reported data on other outcomes or comparisons and hence evidence for these is limited, with confidence intervals often encompassing clinically significant harm and benefit.
AUTHORS' CONCLUSIONS
There is moderate-certainty evidence that ECs with nicotine increase quit rates compared to ECs without nicotine and compared to NRT. Evidence comparing nicotine EC with usual care/no treatment also suggests benefit, but is less certain. More studies are needed to confirm the size of effect, particularly when using modern EC products. Confidence intervals were for the most part wide for data on AEs, SAEs and other safety markers, though evidence indicated no difference in AEs between nicotine and non-nicotine ECs. Overall incidence of SAEs was low across all study arms. We did not detect any clear evidence of harm from nicotine EC, but longest follow-up was two years and the overall number of studies was small. The evidence is limited mainly by imprecision due to the small number of RCTs, often with low event rates. Further RCTs are underway. To ensure the review continues to provide up-to-date information, this review is now a living systematic review. We run searches monthly, with the review updated when relevant new evidence becomes available. Please refer to the Cochrane Database of Systematic Reviews for the review's current status.
Topics: Bias; Carbon Monoxide; Cohort Studies; Electronic Nicotine Delivery Systems; Humans; Middle Aged; Nicotine; Nicotinic Agonists; Outcome Assessment, Health Care; Publication Bias; Randomized Controlled Trials as Topic; Smoking; Smoking Cessation; Smoking Prevention; Tobacco Use Cessation Devices; Vaping
PubMed: 33913154
DOI: 10.1002/14651858.CD010216.pub5 -
BMC Ophthalmology Jul 2023Dry eye disease (DED) is caused by a persistently unstable tear film leading to ocular discomfort and is treated mainly with tear supplementation. There is emerging... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Dry eye disease (DED) is caused by a persistently unstable tear film leading to ocular discomfort and is treated mainly with tear supplementation. There is emerging evidence that nicotinic acetylcholine receptor (nAChR) agonists (e.g., varenicline and simpinicline) nasal sprays are effective for DED. Our systematic review and meta-analysis assessed the efficacy and safety of varenicline nasal spray (VNS) for DED treatment.
METHODS
The Medline, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched. Only randomized controlled trials (RCTs) that evaluated the efficacy of VNS versus placebo were included. The efficacy endpoint was the mean change in the anesthetized Schirmer test score (STS), a measure of basal tear production, from baseline. The safety endpoints were serious adverse events (SAEs) and adverse events (AEs). The standardized mean difference (SMD) was used for continuous outcomes, while the risk ratio (RR) was used to demonstrate dichotomous variables. The certainty of the evidence was rated utilizing the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. The risk of bias assessment was conducted using the Revised Cochrane risk of bias tool for randomized trials.
RESULTS
Three RCTs (n = 1063) met the eligibility criteria. All RCTs had a low risk of bias. The meta-analysis found a statistically significant increase in the mean STS change from baseline on day 28. The pooled analysis found no significant difference between VNS and placebo in the frequency of SAEs and ocular AEs. However, VNS had a significant effect on developing nasal cavity-related AEs.
CONCLUSION
VNS caused a highly significant improvement regarding the efficacy endpoint but caused an increased frequency of some nasal cavity-related AEs (i.e., cough and throat irritation). However, it caused neither SAEs nor ocular AEs. Included studies had a low risk of bias.
Topics: Humans; Nasal Sprays; Varenicline; Dry Eye Syndromes
PubMed: 37452334
DOI: 10.1186/s12886-023-03069-y -
BMJ (Clinical Research Ed.) Mar 2015To determine the risk of neuropsychiatric adverse events associated with use of varenicline compared with placebo in randomised controlled trials. (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
To determine the risk of neuropsychiatric adverse events associated with use of varenicline compared with placebo in randomised controlled trials.
DESIGN
Systematic review and meta-analysis comparing study effects using two summary estimates in fixed effects models, risk differences, and Peto odds ratios.
DATA SOURCES
Medline, Embase, PsycINFO, the Cochrane Central Register of Controlled Trials (CENTRAL), and clinicaltrials.gov.
ELIGIBILITY CRITERIA FOR SELECTING STUDIES
Randomised controlled trials with a placebo comparison group that reported on neuropsychiatric adverse events (depression, suicidal ideation, suicide attempt, suicide, insomnia, sleep disorders, abnormal dreams, somnolence, fatigue, anxiety) and death. Studies that did not involve human participants, did not use the maximum recommended dose of varenicline (1 mg twice daily), and were cross over trials were excluded.
RESULTS
In the 39 randomised controlled trials (10,761 participants), there was no evidence of an increased risk of suicide or attempted suicide (odds ratio 1.67, 95% confidence interval 0.33 to 8.57), suicidal ideation (0.58, 0.28 to 1.20), depression (0.96, 0.75 to 1.22), irritability (0.98, 0.81 to 1.17), aggression (0.91, 0.52 to 1.59), or death (1.05, 0.47 to 2.38) in the varenicline users compared with placebo users. Varenicline was associated with an increased risk of sleep disorders (1.63, 1.29 to 2.07), insomnia (1.56, 1.36 to 1.78), abnormal dreams (2.38, 2.05 to 2.77), and fatigue (1.28, 1.06 to 1.55) but a reduced risk of anxiety (0.75, 0.61 to 0.93). Similar findings were observed when risk differences were reported. There was no evidence for a variation in depression and suicidal ideation by age group, sex, ethnicity, smoking status, presence or absence of psychiatric illness, and type of study sponsor (that is, pharmaceutical industry or other).
CONCLUSIONS
This meta-analysis found no evidence of an increased risk of suicide or attempted suicide, suicidal ideation, depression, or death with varenicline. These findings provide some reassurance for users and prescribers regarding the neuropsychiatric safety of varenicline. There was evidence that varenicline was associated with a higher risk of sleep problems such as insomnia and abnormal dreams. These side effects, however, are already well recognised.
SYSTEMATIC REVIEW REGISTRATION
PROSPERO 2014:CRD42014009224.
Topics: Aggression; Benzazepines; Depression; Humans; Mental Disorders; Quinoxalines; Risk Factors; Sleep Wake Disorders; Suicide; Suicide, Attempted; Tobacco Use Cessation Devices; Varenicline
PubMed: 25767129
DOI: 10.1136/bmj.h1109 -
The Cochrane Database of Systematic... Sep 2019The 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...
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; I = 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; I = 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, I = 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; I = 78%; 11 studies, 8636 participants). However, a significant subgroup analysis (P < 0.001, I = 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.
Topics: Bupropion; Humans; Nicotine; Nicotinic Agonists; Randomized Controlled Trials as Topic; Smoking Cessation; Smoking Reduction; Substance Withdrawal Syndrome; Tobacco Use Cessation Devices
PubMed: 31565800
DOI: 10.1002/14651858.CD013183.pub2 -
Addiction (Abingdon, England) Sep 2016To determine the effectiveness and safety of varenicline in treating tobacco dependence in patients with severe mental illness. (Meta-Analysis)
Meta-Analysis Review
AIMS
To determine the effectiveness and safety of varenicline in treating tobacco dependence in patients with severe mental illness.
DESIGN
A systematic review and meta-analysis of randomised controlled trials that compared varenicline with a placebo or an alternative intervention for smoking cessation or reduction.
SETTING
Both in- and out-patient settings in any country.
PARTICIPANTS
Adult patients aged 18 years and over with any type of severe mental illness. The systematic review included eight studies comprising 398 participants.
MEASURES
Primary outcome measures were (1) smoking cessation, (2) smoking reduction measured by changes in the number of cigarettes smoked per day and (3) number of psychiatric adverse events, which were collected at the end of treatment.
FINDINGS
The random-effect pooled estimates from the five studies that reported smoking-related outcomes found that varenicline is statistically superior to placebo in smoking cessation [risk ratios 4.33; 95% confidence interval (CI) = 1.96-9.56], and smoking reduction was higher in varenicline groups (mean reduced daily cigarettes was 6.39; 95% CI = 2.22-10.56). There is no significant difference regarding neuropsychiatric and other adverse events.
CONCLUSIONS
Varenicline appears to be significantly more effective than placebo in assisting with smoking cessation and reduction in people with severe mental illness. There appears to be no clear evidence that varenicline was associated with an increased risk of neuropsychiatric or other adverse events compared with placebo.
Topics: Comorbidity; Humans; Mental Disorders; Nicotinic Agonists; Smoking; Smoking Cessation; Tobacco Smoking; Varenicline
PubMed: 27043328
DOI: 10.1111/add.13415 -
Psychopharmacology Jan 2020People with schizophrenia frequently have cognitive dysfunction, which does not respond to pharmacological interventions. Varenicline has been identified as a potential... (Meta-Analysis)
Meta-Analysis
BACKGROUND
People with schizophrenia frequently have cognitive dysfunction, which does not respond to pharmacological interventions. Varenicline has been identified as a potential treatment option for nicotinic receptor dysfunction with a potential to treat cognitive impairment in schizophrenia.
METHODS
We conducted a systematic review of Pubmed, Embase, Psycinfo, CINAHL and the Cochrane Schizophrenia Trial Registry for randomised controlled trials of varenicline in people with schizophrenia for cognitive dysfunction. We excluded trials among people with dementia. We then undertook a meta-analysis with the primary outcome of difference in change of cognitive measures between varenicline and placebo as well as secondary outcomes of difference in rates of adverse events. We conducted a sensitivity analysis on smoking status and study duration.
RESULTS
We included four papers in the meta-analysis (n = 339). Varenicline was not superior to placebo for overall cognition (SMD = -0.022, 95% CI -0.154-0.110; Z = -0.333; p = 0.739), attention (SMD = -0.047, 95% CI -0.199-0.104; Z = -0.613; p = 0.540), executive function (SMD = -0.060, 95% CI -0.469-0.348; Z =- 0.290; p = 0.772) or processing speed (SMD = 0.038, 95% CI -0.232-0.308; Z = 0.279; p = 0.780). There was no difference in psychotic symptoms, but varenicline was associated with higher rates of nausea. Sensitivity analyses for smoking status and study duration did not alter the results.
CONCLUSION
Within the present literature, varenicline does not appear to be a useful target compound for improving cognitive impairment in schizophrenia. Based on these results, a trial would need over 2500 participants to be powered to show statistically significant findings.
Topics: Cognitive Dysfunction; Humans; Nicotinic Agonists; Schizophrenia; Varenicline
PubMed: 31792645
DOI: 10.1007/s00213-019-05396-9