Fragility index of network meta-analysis with application to smoking cessation data.
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ABSTRACT: Background and objectives
The network meta-analysis (NMA) is frequently used to synthesize evidence for multiple treatment comparisons, but its complexity may affect the robustness (or fragility) of the results. The fragility index (FI) is recently proposed to assess the fragility of the results from clinical studies and from pairwise meta-analyses. We extend the FI to NMAs with binary outcomes.Methods
We define the FI for each treatment comparison in NMAs. It quantifies the minimal number of events necessary to be modified for altering the comparison's statistical significance. We introduce an algorithm to derive the FI and visualizations of the process. A worked example of smoking cessation data is used to illustrate the proposed methods.Results
Some treatment comparisons had small FIs; their significance (or nonsignificance) could be altered by modifying a few events' status. They were related to various factors, such as P-values, event counts, and sample sizes, in the original NMA. After modifying event status, treatment ranking measures were also changed to different extents.Conclusion
Many NMAs include insufficiently compared treatments, small event counts, or small sample sizes; their results are potentially fragile. The FI offers a useful tool to evaluate treatment comparisons' robustness and reliability.
SUBMITTER: Xing A
PROVIDER: S-EPMC7669670 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:IntroductionConverging clinical and biological evidence suggest sex is an important factor when selecting a pharmacological intervention for smoking cessation. The current investigation used network meta-analyses to estimate sex differences in the comparative efficacy of transdermal nicotine (TN), varenicline, and sustained release (SR) bupropion for smoking cessation.MethodsSystematically searched previously published reviews and databases (Medline, PsycINFO, Embase) of randomized, double-blind, placebo-controlled trials of bupropion-SR, TN, and varenicline for cigarette smoking cessation in primary care/general community samples were included.ResultsThirty-two studies met all criteria and 28 (88%) were included in the final analyses, representing 14 389 smokers (51% female). Results of the full sample (women and men combined) mirrored those from a Cochrane Tobacco Addiction Group network meta-analysis of smoking cessation pharmacotherapy, showing VAR>TN=BUP. All medications improved quit rates over placebo for both women and men. Relative to placebo, varenicline efficacy was similar for women and men. Significant sex differences were evident when comparing varenicline versus TN and varenicline versus bupropion. For women, varenicline was more efficacious than TN (RR = 1.41; 95% CI = 1.12,1.76) and bupropion (RR = 1.38; 95% CI = 1.08,1.77). For men, outcomes for those treated with TN and bupropion were similar to those treated with varenicline. There were no differences in efficacy when comparing bupropion versus TN.ConclusionsThe advantage of varenicline over bupropion SR and TN is greater for women than men. Clinicians should strongly consider varenicline as the first option treatment for women. Among men, the advantage of varenicline over TN or bupropion is less clear.ImplicationsThis study provides information for the sex-informed treatment of nicotine addiction among cigarette smokers. Relative to placebo, women and men achieved similar outcomes when treated with varenicline; however the advantages of varenicline over transdermal patch and bupropion were greater for women compared to men.
| S-EPMC5939704 | biostudies-literature
Project description:Traditional mediation analysis assumes that a study population is homogeneous and the mediation effect is constant over time, which may not hold in some applications. Motivated by smoking cessation data, we propose a latent class dynamic mediation model that explicitly accounts for the fact that the study population may consist of different subgroups and the mediation effect may vary over time. We use a proportional odds model to accommodate the subject heterogeneities and identify latent subgroups. Conditional on the subgroups, we employ a Bayesian hierarchical nonparametric time-varying coefficient model to capture the time-varying mediation process, while allowing each subgroup to have its individual dynamic mediation process. A simulation study shows that the proposed method has good performance in estimating the mediation effect. We illustrate the proposed methodology by applying it to analyze smoking cessation data.
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Project description:BACKGROUND: Smoking remains the leading preventable cause of premature deaths. Several pharmacological interventions now exist to aid smokers in cessation. These include Nicotine Replacement Therapy [NRT], bupropion, and varenicline. We aimed to assess their relative efficacy in smoking cessation by conducting a systematic review and meta-analysis. METHODS: We searched 10 electronic medical databases (inception to Sept. 2006) and bibliographies of published reviews. We selected randomized controlled trials [RCTs] evaluating interventions for smoking cessation at 1 year, through chemical confirmation. Our primary endpoint was smoking cessation at 1 year. Secondary endpoints included short-term smoking cessation (approximately 3 months) and adverse events. We conducted random-effects meta-analysis and meta-regression. We compared treatment effects across interventions using head-to-head trials and when these did not exist, we calculated indirect comparisons. RESULTS: We identified 70 trials of NRT versus control at 1 year, Odds Ratio [OR] 1.71, 95% Confidence Interval [CI], 1.55-1.88, P =< 0.0001). This was consistent when examining all placebo-controlled trials (49 RCTs, OR 1.78, 95% CI, 1.60-1.99), NRT gum (OR 1.60, 95% CI, 1.37-1.86) or patch (OR 1.63, 95% CI, 1.41-1.89). NRT also reduced smoking at 3 months (OR 1.98, 95% CI, 1.77-2.21). Bupropion trials were superior to controls at 1 year (12 RCTs, OR1.56, 95% CI, 1.10-2.21, P = 0.01) and at 3 months (OR 2.13, 95% CI, 1.72-2.64). Two RCTs evaluated the superiority of bupropion versus NRT at 1 year (OR 1.14, 95% CI, 0.20-6.42). Varenicline was superior to placebo at 1 year (4 RCTs, OR 2.96, 95% CI, 2.12-4.12, P =< 0.0001) and also at approximately 3 months (OR 3.75, 95% CI, 2.65-5.30). Three RCTs evaluated the effectiveness of varenicline versus bupropion at 1 year (OR 1.58, 95% CI, 1.22-2.05) and at approximately 3 months (OR 1.61, 95% CI, 1.16-2.21). Using indirect comparisons, varenicline was superior to NRT when compared to placebo controls (OR 1.66, 95% CI 1.17-2.36, P = 0.004) or to all controls at 1 year (OR 1.73, 95% CI 1.22-2.45, P = 0.001). This was also the case for 3-month data. Adverse events were not systematically different across studies. CONCLUSION: NRT, bupropion and varenicline all provide therapeutic effects in assisting with smoking cessation. Direct and indirect comparisons identify a hierarchy of effectiveness.
| S-EPMC1764891 | biostudies-other
Project description:IntroductionThis systematic review of randomized controlled trials (RCTs) evaluated the efficacy and safety of electronic cigarettes (e-cigarettes, ENDS) in helping people who smoke to achieve abstinence compared with electronic non-nicotine delivery systems (ENNDS, no nicotine) or any smoking cessation comparator treatment or combination of treatments at 24-26 weeks and at 52 weeks.MethodsSystematic review techniques involved searches of three databases in February 2020 with update searches run on 14 May 2021, two-person independent screening, two-person independent assessment of bias, formal extraction of data with verification by a second person, a feasibility assessment to decide if meta-analysis was appropriate, and network meta-analysis (NMA) of data at 24-26 weeks. Data at 52 weeks were narratively summarized.ResultsTen RCTs met the inclusion criteria, eight for efficacy and ten for safety. Eight of the nine RCTs were assessed as at high risk of bias. The sample sizes of the RCTs were 30-2012. Using nicotine replacement therapy (NRT) as the reference treatment, the incidences of smoking cessation at 24-26 weeks were comparable between ENDS and NRT groups (RR=1.17; 95% CrI: 0.66-1.86). Three sensitivity analyses were carried out indicating the main findings for 24-26 weeks were robust to assumptions. The findings at 52 weeks were inconclusive.ConclusionsThis systematic review and NMA indicates that there is no clear evidence of a difference in effect between nicotine containing e-cigarettes and NRT on incidences of smoking cessation at 24-26 weeks, and substantial uncertainty remains.
| S-EPMC8607936 | biostudies-literature
Project description:BackgroundMany placebo-controlled trials have demonstrated the efficacy of individual pharmacotherapies approved for smoking cessation. However, few direct or indirect comparisons of such interventions have been conducted. We performed a meta-analysis to compare the treatment effects of 7 approved pharmacologic interventions for smoking cessation.MethodsWe searched the US Centers for Disease Control and Prevention's Tobacco Information and Prevention database as well as MEDLINE, EMBASE and the Cochrane Library for published reports of placebo-controlled, double-blind randomized controlled trials of pharmacotherapies for smoking cessation. We included studies that reported biochemically validated measures of abstinence at 6 and 12 months. We used a hierarchical Bayesian random-effects model to summarize the results for each intervention.ResultsWe identified 70 published reports of 69 trials involving a total of 32 908 patients. Six of the 7 pharmacotherapies studied were found to be more efficacious than placebo: varenicline (odds ratio [OR] 2.41, 95% credible interval [CrI] 1.91-3.12), nicotine nasal spray (OR 2.37, 95% CrI 1.12-5.13), bupropion (OR 2.07, 95% CrI 1.73-2.55), transdermal nicotine (OR 2.07, 95% CrI 1.69-2.62), nicotine tablet (OR 2.06, 95% CrI 1.12-5.13) and nicotine gum (OR 1.71, 95% CrI 1.35-2.21). Similar results were obtained regardless of which measure of abstinence was used. Although the point estimate favoured nicotine inhaler over placebo (OR 2.17), these results were not conclusive because the credible interval included unity (95% CrI 0.95-5.43). When all 7 interventions were included in the same model, all were more efficacious than placebo. In our analysis of data from the varenicline trials that included bupropion control arms, we found that varenicline was superior to bupropion (OR 2.18, 95% CrI 1.09-4.08).InterpretationVarenicline, bupropion and the 5 nicotine replacement therapies were all more efficacious than placebo at promoting smoking abstinence at 6 and 12 months.
| S-EPMC2443223 | biostudies-literature
Project description:ObjectivesThis meta-analysis sought to evaluate the efficacy of opioid antagonists in promoting long-term smoking cessation. Post-treatment abstinence was examined as a secondary outcome and effects on withdrawal symptoms, craving and reduced consumption were also explored.DesignThe search strategy for this meta-analysis included clinical trials (published and unpublished data) in the Cochrane Tobacco Addiction Group Specialized Register and MEDLINE.ParticipantsAdult smokers.InterventionsWe included randomised trials comparing opioid antagonists to placebo or an alternative therapy for smoking cessation and reported data on abstinence for a minimum of 6 months.Primary and secondary outcome measuresOutcomes included smoking abstinence at long-term follow-up (primary); abstinence at end of treatment (secondary); and effects on withdrawal, craving and smoking consumption (exploratory).Results8 trials with a total of 1213 participants were included. Half the trials examined the benefit of adding naltrexone versus placebo to nicotine replacement therapy (NRT). There was no significant difference between naltrexone and placebo alone (relative risk (RR) 1.00; 95% CI 0.66 to 1.51) or as an adjunct to NRT (RR 0.95; 95% CI 0.70 to 1.30), with an overall pooled estimate of RR 0.97; 95% CI 0.76 to 1.24. Findings for naltrexone effects on withdrawal, craving and reduced smoking were equivocal.ConclusionsThe findings indicate no beneficial effect of naltrexone alone or as an adjunct to NRT on short-term or long-term smoking abstinence. While further trials may narrow the confidence limits, they are unlikely to appreciably alter the conclusion.
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Project description:IntroductionWomen have lower rates of quitting than men with both bupropion and nicotine replacement. It is unknown whether varenicline demonstrates differential efficacy for men and women. The purpose of this study was to conduct the first comprehensive meta-analysis of clinical trial data examining sex differences in the efficacy of varenicline for smoking cessation.MethodsSearching MEDLINE, EMBASE, and PsychINFO, 17 of 43 clinical trials of varenicline for smoking cessation published through December 31, 2014 were low-bias randomized double-blind placebo-controlled trials. Data (n = 6710 smokers, 34% female, n = 16 studies, 96% of available data) was analyzed with Metafor program in R. Outcome endpoints were 7-day point-prevalence (PP) and continuous-abstinence (CA) at week 12 (end of treatment), week 24 (6-month follow-up), and week 52 (12-month follow-up).ResultsUsing placebo, women were less likely than men to quit (PP-12, CA-24; P < .05 for sex). Using varenicline, similar rates of abstinence for men and women were demonstrated for all six outcomes (eg, PP-12 abstinence rates were 53% in both women and men). Varenicline versus placebo outcomes demonstrated that varenicline was more effective for women for short and intermediate outcomes (PP-12, CA-12, CA-24; P < .05 sex × medication interaction). For end-of-treatment PP, varenicline was 46% more effective for women. For continuous abstinence, varenicline was 34% (CA-12) and 31% (CA-24) more effective for women.ConclusionsUnlike other smoking cessation medications, varenicline demonstrated greater efficacy among women smokers for short and immediate-term outcomes and equal efficacy for 1-year outcomes. Varenicline may be particularly useful for reducing the sex disparity typically seen in rates of smoking cessation.ImplicationsVarenicline is currently the most effective FDA-approved smoking cessation medication and this is the first demonstration that women compared with men have a preferred therapeutic response for a smoking cessation medication when considering short-term outcomes. Importantly, this is also the first demonstration that women have similar rates of quitting to men when considering longer-term, 1-year outcomes.
| S-EPMC5942618 | biostudies-literature
Project description:ObjectivesTo evaluate the effects of more intensive smoking cessation interventions compared to less intensive interventions on smoking cessation in people with type 1 or type 2 diabetes.DesignA systematic review and meta-analysis of randomised trials of smoking cessation interventions was conducted. Electronic searches were carried out on the following databases: MEDLINE, EMBASE, CINAHL and PsycINFO to September 2013. Searches were supplemented by review of trial registries and references from identified trials. Citations and full-text articles were screened by two reviewers. A random-effect Mantel-Haenszel model was used to pool data.SettingPrimary, secondary and tertiary care.ParticipantsAdults with type 1 or type 2 diabetes.InterventionsSmoking cessation interventions or medication (more intensive interventions) compared to usual care, counselling or optional medication (less intensive interventions).Outcome measuresBiochemically verified smoking cessation was the primary outcome. Secondary outcomes were adverse events and effects on glycaemic control. We also carried out a pooled analysis of self-reported smoking cessation outcomes.ResultsWe screened 1783 citations and reviewed seven articles reporting eight trials in 872 participants. All trials were of 6 months duration. Three trials included pharmacotherapy for smoking cessation. The risk ratio of biochemically verified smoking cessation was 1.32 (95% CI 0.23 to 7.43) for the more intensive interventions compared to less intensive interventions with significant heterogeneity (I(2)=76%). Only one trial reported measures of glycaemic control.ConclusionsThere is an absence of evidence of efficacy for more intensive smoking cessation interventions in people with diabetes. The more intensive strategies tested in trials to date include interventions used in the general population, adding in diabetes-specific education about increased risk. Future research should focus on multicomponent smoking cessation interventions carried out over a period of at least 1 year, and also assess impact on glycaemic control.
| S-EPMC3948637 | biostudies-literature
Project description:ObjectiveTo investigate change in mental health after smoking cessation compared with continuing to smoke.DesignSystematic review and meta-analysis of observational studies.Data sourcesWeb of Science, Cochrane Central Register of Controlled Trials, Medline, Embase, and PsycINFO for relevant studies from inception to April 2012. Reference lists of included studies were hand searched, and authors were contacted when insufficient data were reported.Eligibility criteria for selecting studiesLongitudinal studies of adults that assessed mental health before smoking cessation and at least six weeks after cessation or baseline in healthy and clinical populations.Results26 studies that assessed mental health with questionnaires designed to measure anxiety, depression, mixed anxiety and depression, psychological quality of life, positive affect, and stress were included. Follow-up mental health scores were measured between seven weeks and nine years after baseline. Anxiety, depression, mixed anxiety and depression, and stress significantly decreased between baseline and follow-up in quitters compared with continuing smokers: the standardised mean differences (95% confidence intervals) were anxiety -0.37 (95% confidence interval -0.70 to -0.03); depression -0.25 (-0.37 to -0.12); mixed anxiety and depression -0.31 (-0.47 to -0.14); stress -0.27 (-0.40 to -0.13). Both psychological quality of life and positive affect significantly increased between baseline and follow-up in quitters compared with continuing smokers 0.22 (0.09 to 0.36) and 0.40 (0.09 to 0.71), respectively). There was no evidence that the effect size differed between the general population and populations with physical or psychiatric disorders.ConclusionsSmoking cessation is associated with reduced depression, anxiety, and stress and improved positive mood and quality of life compared with continuing to smoke. The effect size seems as large for those with psychiatric disorders as those without. The effect sizes are equal or larger than those of antidepressant treatment for mood and anxiety disorders.
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Project description:Background:Smoking has been associated with colorectal cancer (CRC) incidence and mortality in previous studies and might also be associated with prognosis after CRC diagnosis. However, current evidence on smoking in association with CRC prognosis is limited. Patients and methods:For this individual patient data meta-analysis, sociodemographic and smoking behavior information of 12?414 incident CRC patients (median age at diagnosis: 64.3?years), recruited within 14 prospective cohort studies among previously cancer-free adults, was collected at baseline and harmonized across studies. Vital status and causes of death were collected for a mean follow-up time of 5.1?years following cancer diagnosis. Associations of smoking behavior with overall and CRC-specific survival were evaluated using Cox regression and standard meta-analysis methodology. Results:A total of 5229 participants died, 3194 from CRC. Cox regression revealed significant associations between former [hazard ratio (HR)?=?1.12; 95 % confidence interval (CI)?=?1.04-1.20] and current smoking (HR?=?1.29; 95% CI?=?1.04-1.60) and poorer overall survival compared with never smoking. Compared with current smoking, smoking cessation was associated with improved overall (HR<10?years?=?0.78; 95% CI?=?0.69-0.88; HR?10?years?=?0.78; 95% CI?=?0.63-0.97) and CRC-specific survival (HR?10?years?=?0.76; 95% CI?=?0.67-0.85). Conclusion:In this large meta-analysis including primary data of incident CRC patients from 14 prospective cohort studies on the association between smoking and CRC prognosis, former and current smoking were associated with poorer CRC prognosis compared with never smoking. Smoking cessation was associated with improved survival when compared with current smokers. Future studies should further quantify the benefits of nonsmoking, both for cancer prevention and for improving survival among CRC patients, in particular also in terms of treatment response.
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