Non-vitamin K antagonist oral anticoagulants (NOACs) after transcatheter aortic valve replacement (TAVR): a network meta-analysis.

Balancing the risk of thromboembolism and bleeding after transcatheter aortic valve replacement (TAVR) remains clinically challenging. Questions regarding the efficacy and safety of non-vitamin K oral anticoagulants (NOACs) after TAVR still need to be definitively answered. To evaluate the efficacy and safety of NOACs after TAVR in individuals with and without indication for anticoagulation. We searched CENTRAL, MEDLINE, Embase, Web of Science, ClinicalTrials.gov, and WHO ICTRP on 7 October 2023 together with reference checking and citation searching to identify additional studies. We searched for randomised controlled trials (RCTs) that compared NOACs versus antiplatelet therapy or vitamin K antagonists (VKAs) after TAVR in adults with or without an indication for anticoagulation. We used standard Cochrane methods and conducted random-effects pair-wise analyses and network meta-analyses (NMAs). Our primary outcomes were all-cause mortality, cardiovascular mortality, stroke, and major bleeding. We used GRADE to assess the certainty of evidence. We included four RCTs with 4808 participants in the NMA. Of these, one compared rivaroxaban versus antiplatelet therapy in people without an indication for anticoagulation after TAVR; one compared apixaban versus antiplatelet therapy in people without an indication for anticoagulation or versus VKA in people with an indication for anticoagulation after TAVR; one compared edoxaban versus VKA in people with an indication for anticoagulation after TAVR; and one compared edoxaban with antiplatelet therapy in people without an indication for anticoagulation after TAVR. The mean age of trial participants was 81 years. Follow-up duration ranged from 6 to 18 months. Overall, we judged the risk of bias in the included trials to be low in all domains except for blinding, which was assessed as high in all four studies. No studies evaluated dabigatran. In people without an indication for anticoagulation, rivaroxaban and apixaban may increase all-cause mortality after TAVR as compared to antiplatelet therapy (rivaroxaban: risk ratio (RR) 1.67, 95% confidence interval (CI) 1.13 to 2.46; studies = 1, participants = 1644; moderate-certainty evidence; apixaban: RR 1.71, 95% CI 0.97 to 3.02; studies = 1, participants = 1049; low-certainty evidence), while edoxaban may result in little or no difference (RR 1.59, 95% CI 0.27 to 9.36; studies = 1, participants = 229; low-certainty evidence). Low-certainty evidence suggests little or no difference between rivaroxaban, apixaban, or edoxaban and antiplatelet therapy in cardiovascular mortality (rivaroxaban: RR 1.28, 95% CI 0.78 to 2.10; studies = 1, participants = 1644; apixaban: RR 1.30, 95% CI 0.64 to 2.65; studies = 1, participants = 1049; edoxaban: RR 7.44, 95% CI 0.39 to 142.38; studies = 1, participants = 229) and between rivaroxaban or edoxaban and antiplatelets in stroke (rivaroxaban: RR 1.19, 95% CI 0.71 to 2.00; studies = 1, participants = 1644; edoxaban: RR 1.06, 95% CI 0.15 to 7.42; studies = 1, participants = 229). While rivaroxaban versus antiplatelets probably increases major bleeding after TAVR (RR 1.98, 95% CI 1.07 to 3.65; studies = 1, participants = 1644; moderate-certainty evidence), there may be little or no difference between apixaban and antiplatelet therapy (RR 1.07, 95% CI 0.70 to 1.64; studies = 1, participants = 1049; low-certainty evidence). It is unclear if edoxaban has an effect on major bleeding, although the point estimate suggests increased bleeding (versus antiplatelets: RR 2.13, 95% CI 0.54 to 8.30; studies = 1, participants = 229; low-certainty evidence). In people with an indication for anticoagulation, low-certainty evidence suggests apixaban or edoxaban may result in little to no difference in our predefined primary efficacy outcomes after TAVR when compared to VKA (all-cause mortality: apixaban: RR 1.02, 95% CI 0.59 to 1.77; studies = 1, participants = 451; edoxaban: RR 0.91, 95% CI 0.69 to 1.20; studies = 1, participants = 1426; cardiovascular mortality: apixaban: RR 1.43, 95% CI 0.76 to 2.70; studies = 1, participants = 451; edoxaban: RR 1.07, 95% CI 0.72 to 1.57; studies = 1, participants = 1426; stroke: apixaban: RR 1.28, 95% CI 0.35 to 4.70; studies = 1, participants = 451; edoxaban: RR 0.83, 95% CI 0.51 to 1.34; studies = 1, participants = 1426). While apixaban may result in a similar rate of bleeding as VKA in this population, edoxaban probably increases major bleeding after TAVR in people with an indication for anticoagulation (apixaban: RR 0.90, 95% CI 0.53 to 1.54; studies = 1, participants = 451; low-certainty evidence; edoxaban: RR 1.44, 95% CI 1.08 to 1.93; studies = 1, participants = 1426; moderate-certainty evidence). In people without an indication for oral anticoagulation, rivaroxaban and apixaban may increase all-cause mortality when compared to antiplatelet therapy, while edoxaban may result in little or no difference. There might be little or no difference between rivaroxaban, apixaban, or edoxaban and antiplatelet therapy in cardiovascular mortality, and between rivaroxaban or edoxaban and antiplatelets in stroke. While rivaroxaban probably increases major bleeding following TAVR, there might be little or no difference between apixaban and antiplatelet therapy, and the effect of edoxaban on major bleeding remains unclear. In people with an indication for anticoagulation, apixaban and edoxaban may be as effective as VKA in preventing all-cause mortality, cardiovascular death, and stroke. Apixaban may lead to a similar rate of major bleeding as VKA in this population. However, edoxaban probably increases major bleeding following TAVR when compared to VKA. Our NMA did not show superiority of one NOAC over another for any of the primary outcomes. Head-to-head trials directly comparing NOACs against each other are required to increase the certainty of the evidence.

Al Said S ，Kaier K ，Nury E ，Alsaid D ，Gibson CM ，Bax J ，Westermann D ，Meerpohl JJ ... -  《Cochrane Database of Systematic Reviews》

Non-vitamin-K-antagonist oral anticoagulants (NOACs) after acute myocardial infarction: a network meta-analysis.

Balancing the risk of bleeding and thrombosis after acute myocardial infarction (AMI) is challenging, and the optimal antithrombotic therapy remains uncertain. The potential of non-vitamin K antagonist oral anticoagulants (NOACs) to prevent ischaemic cardiovascular events is promising, but the evidence remains limited. To evaluate the efficacy and safety of non-vitamin-K-antagonist oral anticoagulants (NOACs) in addition to background antiplatelet therapy, compared with placebo, antiplatelet therapy, or both, after acute myocardial infarction (AMI) in people without an indication for anticoagulation (i.e. atrial fibrillation or venous thromboembolism). We searched CENTRAL, MEDLINE, Embase, the Conference Proceedings Citation Index - Science, and two clinical trial registers in September 2022 with no language restrictions. We checked the reference lists of included studies for any additional trials. We searched for randomised controlled trials (RCTs) that evaluated NOACs plus antiplatelet therapy versus placebo, antiplatelet therapy, or both, in people without an indication for anticoagulation after an AMI. Two review authors independently checked the results of searches to identify relevant studies, assessed each included study, and extracted study data. We conducted random-effects pairwise analyses using Review Manager Web, and network meta-analysis using the R package 'netmeta'. We ranked competing treatments by P scores, which are derived from the P values of all pairwise comparisons and allow ranking of treatments on a continuous 0-to-1 scale. We identified seven eligible RCTs, including an ongoing trial that we could not include in the analysis. Of the six RCTs involving 33,039 participants, three RCTs compared rivaroxaban with placebo, two RCTs compared apixaban with placebo, and one RCT compared dabigatran with placebo. All participants in the six RCTs received concomitant antiplatelet therapy. The available evidence suggests that rivaroxaban compared with placebo reduces the rate of all-cause mortality (risk ratio (RR) 0.82, 95% confidence interval (CI) 0.69 to 0.98; number needed to treat for an additional beneficial outcome (NNTB) 250; 3 studies, 21,870 participants; high certainty) and probably reduces cardiovascular mortality (RR 0.83, 95% CI 0.69 to 1.01; NNTB 250; 3 studies, 21,870 participants; moderate certainty). There is probably little or no difference between apixaban and placebo in all-cause mortality (RR 1.09, 95% CI 0.88 to 1.35; number needed to treat for an additional harmful outcome (NNTH) 334; 2 studies, 8638 participants; moderate certainty) and cardiovascular mortality (RR 0.99, 95% CI 0.77 to 1.27; number needed to treat not applicable; 2 studies, 8638 participants; moderate certainty). Dabigatran may reduce the rate of all-cause mortality compared with placebo (RR 0.57, 95% CI 0.31 to 1.06; NNTB 63; 1 study, 1861 participants; low certainty). Dabigatran compared with placebo may have little or no effect on cardiovascular mortality, although the point estimate suggests benefit (RR 0.72, 95% CI 0.34 to 1.52; NNTB 143; 1 study, 1861 participants; low certainty). Two of the investigated NOACs were associated with an increased risk of major bleeding compared to placebo: apixaban (RR 2.41, 95% CI 1.44 to 4.06; NNTH 143; 2 studies, 8544 participants; high certainty) and rivaroxaban (RR 3.31, 95% CI 1.12 to 9.77; NNTH 125; 3 studies, 21,870 participants; high certainty). There may be little or no difference between dabigatran and placebo in the risk of major bleeding (RR 1.74, 95% CI 0.22 to 14.12; NNTH 500; 1 study, 1861 participants; low certainty). The results of the network meta-analysis were inconclusive between the different NOACs at all individual doses for all primary outcomes. However, low-certainty evidence suggests that apixaban (combined dose) may be less effective than rivaroxaban and dabigatran for preventing all-cause mortality after AMI in people without an indication for anticoagulation. Compared with placebo, rivaroxaban reduces all-cause mortality and probably reduces cardiovascular mortality after AMI in people without an indication for anticoagulation. Dabigatran may reduce the rate of all-cause mortality and may have little or no effect on cardiovascular mortality. There is probably no meaningful difference in the rate of all-cause mortality and cardiovascular mortality between apixaban and placebo. Moreover, we found no meaningful benefit in efficacy outcomes for specific therapy doses of any investigated NOACs following AMI in people without an indication for anticoagulation. Evidence from the included studies suggests that rivaroxaban and apixaban increase the risk of major bleeding compared with placebo. There may be little or no difference between dabigatran and placebo in the risk of major bleeding. Network meta-analysis did not show any superiority of one NOAC over another for our prespecified primary outcomes. Although the evidence suggests that NOACs reduce mortality, the effect size or impact is small; moreover, NOACs may increase major bleeding. Head-to-head trials, comparing NOACs against each other, are required to provide more solid evidence.

Al Said S ，Kaier K ，Sumaya W ，Alsaid D ，Duerschmied D ，Storey RF ，Gibson CM ，Westermann D ，Alabed S ... -  《Cochrane Database of Systematic Reviews》

Direct factor Xa inhibitors versus low molecular weight heparins or vitamin K antagonists for prevention of venous thromboembolism in elective primary hip or knee replacement or hip fracture repair.

People undergoing major orthopaedic surgery are at increased risk of postoperative thromboembolic events. Low molecular weight heparins (LMWHs) are recommended for thromboprophylaxis in this population. New oral anticoagulants, including direct factor Xa inhibitors, are recommended as alternatives. They may have more advantages than disadvantages compared to LMWHs and vitamin K antagonists (VKAs, another type of anticoagulant). To assess the benefits and harms of prophylactic anticoagulation with direct factor Xa inhibitors compared with low molecular weight heparins and vitamin K antagonists in people undergoing major orthopaedic surgery for elective total hip or knee replacement or hip fracture surgery. We searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, two other databases, and two trial registers to 11 November 2023. We conducted reference checks to identify additional studies. We included randomised controlled trials (RCTs) comparing the effects of direct factor Xa inhibitors to LMWHs or VKAs in people undergoing major orthopaedic surgery. We used standard Cochrane methods. Our primary outcomes were all-cause mortality, major venous thromboembolism (VTE), symptomatic VTE, major bleeding, and serious hepatic and non-hepatic adverse events. We evaluated the risk of bias in the included studies using Cochrane's risk of bias 1 tool. We calculated estimates of treatment effects using risk ratios (RR) with 95% confidence intervals (CIs), and used GRADE criteria to assess the certainty of the evidence. We included 53 RCTs (44,371 participants). Participants' average age was 64 years (range: 18 to 93 years). Only one RCT compared a VKA with direct factor Xa inhibitors. All 53 RCTs compared direct factor Xa inhibitors with LMWHs. Twenty-three studies included participants undergoing total hip replacement; 21 studies, total knee replacement; and three studies included people having hip fracture surgery. The studies' average duration was approximately 42 days (range: two to 720 days). Compared to LMWHs, direct factor Xa inhibitors may have little to no effect on all-cause mortality, but the evidence is very uncertain (RR 0.83, 95% CI 0.52 to 1.31; I2 = 0%; 28 studies, 29,698 participants; very low-certainty evidence). Direct factor Xa inhibitors may make little to no difference to major venous thromboembolic events compared to LMWHs, but the evidence is very uncertain (RR 0.51, 95% CI 0.37 to 0.71; absolute risk difference: 12 fewer major VTE events per 1000 participants, 95% CI 16 fewer to 7 fewer; I2 = 48%; 28 studies, 24,574 participants; very low-certainty evidence). Compared to LMWHs, direct factor Xa inhibitors may reduce symptomatic VTE (RR 0.64, 95% CI 0.50 to 0.83; I2 = 0%; 33 studies, 31,670 participants; low-certainty evidence). The absolute benefit of substituting factor Xa inhibitors for LMWHs may be between two and five fewer symptomatic VTE episodes per 1000 patients. In the meta-analysis with all studies pooled, direct factor Xa inhibitors appeared to make little or no difference to major bleeding compared to LMWHs, but the evidence was very uncertain (RR 1.05, 95% CI 0.86 to 1.30; I2 = 15%; 36 studies, 39,778 participants; very low certainty-evidence). • In a subgroup analysis limited to studies comparing rivaroxaban to LMWHs, people given rivaroxaban may have had more major bleeding events (RR 1.94, 95% CI 1.26 to 2.98; I2 = 0%; 17 studies, 17,630 participants; low-certainty evidence). The absolute risk of substituting rivaroxaban for LMWH may be between one and seven more major bleeding events per 1000 patients. • In a subgroup analysis limited to studies comparing direct factor Xa inhibitors other than rivaroxaban to LMWHs, people given these other direct factor Xa inhibitors may have had fewer major bleeding events, but the evidence was very uncertain (RR 0.80, 95% CI 0.63 to 1.02; absolute risk difference: 3 fewer major bleeding events per 1000 participants, 95% CI 5 fewer to 0 fewer; I2 = 0%; 19 studies, 22,148 participants; very low-certainty evidence). Direct factor Xa inhibitors may make little to no difference in serious hepatic adverse events compared to LMWHs, but the evidence is very uncertain (RR 3.01, 95% CI 0.12 to 73.93; 2 studies, 3169 participants; very low-certainty evidence). Only two studies reported this outcome, with one death in the intervention group due to hepatitis reported in one study, and no events reported in the other study. People given direct factor Xa inhibitors may have a lower risk of serious non-hepatic adverse events than those given LMWHs (RR 0.89, 95% CI 0.81 to 0.97; I2 = 18%; 15 studies, 26,246 participants; low-certainty evidence). The absolute benefit of substituting factor Xa inhibitors for LMWH may be between three and 14 fewer serious non-hepatic adverse events per 1000 patients. Only one study compared a direct factor Xa inhibitor with a VKA. It reported outcome data with imprecise results due to the small number of events. It showed no difference in the effects of the study drugs. Oral direct factor Xa inhibitors may have little to no effect on all-cause mortality, but the evidence is very uncertain. Oral direct factor Xa inhibitors may slightly reduce symptomatic VTE events when compared with LMWH. They may make little or no difference to major VTE events, but the evidence is very uncertain. In the evaluation of major bleeding, the evidence suggests rivaroxaban results in a slight increase in major bleeding events compared to LMWHs. The remaining oral direct factor Xa inhibitors may have little to no effect on major bleeding, but the evidence is very uncertain. Oral direct factor Xa inhibitors may reduce serious non-hepatic adverse events slightly compared to LMWHs. They may have little to no effect on serious hepatic adverse events, but the evidence is very uncertain. Due to the high rates of missing participants and selective outcome reporting, the effect estimates may be biased.

Salazar CA ，Basilio Flores JE ，Malaga G ，Malasquez GN ，Bernardo R ... -  《Cochrane Database of Systematic Reviews》

Interrupted versus uninterrupted anticoagulation for cardiac rhythm management device insertion.

Guideline-recommended strategies to interrupt chronic anticoagulation with warfarin or direct oral anticoagulants (DOAC) during the perioperative period of cardiac implantable electronic device (CIED) surgery differ worldwide. There is uncertainty concerning the benefits and harms of interrupted and uninterrupted anticoagulation in patients undergoing CIED surgery. To assess the benefits and harms of interrupted anticoagulation (IAC) with either warfarin or DOAC in the perioperative period of CIED surgery versus uninterrupted anticoagulation (UAC), with or without heparin bridging, during an equivalent time frame, for CIED surgery. CENTRAL, MEDLINE, Embase, Web of Science, and two trials registers were searched on 26 November 2021 together with reference checking, citation searching and contact with study authors to identify additional studies. We plan to update this review imminently. We included randomized controlled trials (RCTs) evaluating IAC vs. UAC in adults with a diagnosed cardiac rhythm disorder, who underwent elective CIED surgery and received at least one month of warfarin or DOAC anticoagulation. Comparisons of interest were: (1) continued warfarin vs. interrupted warfarin anticoagulation, with or without heparin bridging; and (2) continued DOAC (apixaban, betrixaban, dabigatran, edoxaban, or rivaroxaban) vs. interrupted DOAC, with or without heparin bridging. Primary outcomes were composite thromboembolic events (transient ischemic attack, ischemic stroke, deep vein thrombosis, pulmonary embolism, peripheral embolism, or valve thrombosis) and device-pocket hematoma. Secondary outcomes included individual components of composite thromboembolic events, composite bleeding events, all-cause mortality, adverse events, quality of life and days of hospitalization. Two authors independently selected studies, extracted data, and assessed the risk of bias. We assessed the certainty of evidence using GRADE. The inverse variance random-effects model was used for meta-analyses, and the DerSimonian and Laird method was used for calculating the between-study variance Tau2. Dichotomous outcomes were calculated as risk ratios (RRs) and we used mean differences (MDs) for continuous outcomes, with respective 95% confidence intervals (95% CIs). We identified 10 eligible studies (2221 participants), of which one is ongoing. Of these 10 studies, six compared IAC vs. UAC with warfarin (1267 participants) and four compared IAC vs. UAC with DOAC (954 participants). Follow-up duration ranged between 0.5 to three months. The mean age of participants ranged from 68 to 76 years. Definitions of thromboembolic events, device-pocket hematoma, and bleeding events varied across studies. IAC vs. UAC with warfarin IAC with warfarin may result in little to no difference in composite thromboembolic events (RR 0.85, 95% CI 0.18 to 4.11; 5 RCTs, n = 1266; low-certainty evidence). The evidence is very uncertain about the effect of IAC on device-pocket hematoma (RR 1.87, 95% CI 0.83 to 4.22; 5 RCTs, n = 1266; very low-certainty evidence), ischemic stroke (RR 0.70, 95% CI 0.11 to 4.40; 5 RCTs, n = 1266; very low-certainty evidence) and composite bleeding events (RR 1.92, 95% CI 0.84 to 4.43; 5 RCTs, very low-certainty evidence). IAC with warfarin likely results in little to no difference in deep vein thrombosis or pulmonary embolism (0 events in both groups; 2 RCTs, n = 782; moderate-certainty evidence). IAC may result in a slight reduction of all-cause mortality (RR 0.35, 95% CI 0.04 to 2.93; 3 RCTs, n = 953; low-certainty evidence). IAC vs. UAC with DOAC IAC with DOAC may result in little to no difference in composite thromboembolic events (RR 0.98, 95% CI 0.06 to 15.63; 3 RCTs, n = 843; low-certainty evidence) and ischemic stroke (RR 0.98, 95% CI 0.06 to 15.63, 2 RCTs, n = 763; low-certainty evidence). The evidence is very uncertain about the effect of IAC with DOAC on device-pocket hematoma (RR 1.07, 95% CI 0.55 to 2.11; 4 RCTs, n = 954; very low-certainty evidence) and composite bleeding events (RR 1.07, 95% CI 0.55 to 2.06; 4 RCTs, n = 954; very low-certainty evidence). IAC may result in little to no difference in ischemic stroke (RR 0.98, 95% CI 0.06 to 15.63, 2 RCTs, low-certainty evidence). IAC likely results in little to no difference in deep vein thrombosis or pulmonary embolism (0 events in both groups; 2 RCTs, n = 763; moderate-certainty evidence). IAC may result in a slight reduction of all-cause mortality (RR 0.49, 95% CI 0.04 to 5.39; 2 RCTs, n = 763; low-certainty evidence). Interrupted anticoagulation in people undergoing elective CIED surgery had similar outcomes to uninterrupted anticoagulation with either warfarin or DOAC medications. Certainty of evidence was judged to be low to very low for most of the assessed outcomes. Further RCTs are particularly needed to help identify whether IAC significantly impacts the risks of thromboembolic events and device-pocket hematoma.

Chen B ，Phan M ，Pasupuleti V ，Roman YM ，Hernandez AV ... -  《Cochrane Database of Systematic Reviews》

Electronic cigarettes for smoking cessation.

Electronic cigarettes (ECs) are handheld electronic vaping devices that produce an aerosol by heating an e-liquid. People who smoke, healthcare providers, and regulators want to know if ECs can help people quit smoking, and if they are safe to use for this purpose. This is a review update conducted as part of a living systematic review. To examine the safety, tolerability, and effectiveness of using EC to help people who smoke tobacco achieve long-term smoking abstinence, in comparison to non-nicotine EC, other smoking cessation treatments, and no treatment. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and PsycINFO to 1 February 2024 and the Cochrane Tobacco Addiction Group's Specialized Register to 1 February 2023, reference-checked, and contacted study authors. We included trials randomizing people who smoke to an EC or control condition. We included uncontrolled intervention studies in which all participants received an EC intervention. Studies had to report an eligible outcome. We followed standard Cochrane methods for screening and data extraction. We used the risk of bias tool (RoB 1) and GRADE to assess the certainty of evidence. Critical outcomes were abstinence from smoking after at least six months, adverse events (AEs), and serious adverse events (SAEs). Important outcomes were biomarkers, toxicants/carcinogens, and longer-term EC use. We used a fixed-effect Mantel-Haenszel model to calculate risk ratios (RRs) with a 95% confidence interval (CI) for dichotomous outcomes. For continuous outcomes, we calculated mean differences. Where appropriate, we pooled data in pairwise and network meta-analyses (NMA). We included 90 completed studies (two new to this update), representing 29,044 participants, of which 49 were randomized controlled trials (RCTs). Of the included studies, we rated 10 (all but one contributing to our main comparisons) at low risk of bias overall, 61 at high risk overall (including all non-randomized studies), and the remainder at unclear risk. Nicotine EC results in increased quit rates compared to nicotine replacement therapy (NRT) (high-certainty evidence) (RR 1.59, 95% CI 1.30 to 1.93; I2 = 0%; 7 studies, 2544 participants). In absolute terms, this might translate to an additional four quitters per 100 (95% CI 2 to 6 more). The rate of occurrence of AEs is probably similar between groups (moderate-certainty evidence (limited by imprecision)) (RR 1.03, 95% CI 0.91 to 1.17; I2 = 0%; 5 studies, 2052 participants). SAEs were rare, and there is insufficient evidence to determine whether rates differ between groups due to very serious imprecision (RR 1.20, 95% CI 0.90 to 1.60; I2 = 32%; 6 studies, 2761 participants; low-certainty evidence). Nicotine EC probably results in increased quit rates compared to non-nicotine EC (moderate-certainty evidence, limited by imprecision) (RR 1.46, 95% CI 1.09 to 1.96; I2 = 4%; 6 studies, 1613 participants). In absolute terms, this might lead to an additional three quitters per 100 (95% CI 1 to 7 more). There is probably little to no difference in the rate of AEs between these groups (moderate-certainty evidence) (RR 1.01, 95% CI 0.91 to 1.11; I2 = 0%; 5 studies, 840 participants). There is insufficient evidence to determine whether rates of SAEs differ between groups, due to very serious imprecision (RR 1.00, 95% CI 0.56 to 1.79; I2 = 0%; 9 studies, 1412 participants; low-certainty evidence). Compared to behavioural support only/no support, quit rates may be higher for participants randomized to nicotine EC (low-certainty evidence due to issues with risk of bias) (RR 1.96, 95% CI 1.66 to 2.32; I2 = 0%; 11 studies, 6819 participants). In absolute terms, this represents an additional four quitters per 100 (95% CI 3 to 5 more). There was some evidence that (non-serious) AEs may be more common in people randomized to nicotine EC (RR 1.18, 95% CI 1.10 to 1.27; I2 = 6%; low-certainty evidence; 6 studies, 2351 participants) and, again, insufficient evidence to determine whether rates of SAEs differed between groups (RR 0.93, 95% CI 0.68 to 1.28; I2 = 0%; 12 studies, 4561 participants; very low-certainty evidence). Results from the NMA were consistent with those from pairwise meta-analyses for all critical outcomes. There was inconsistency in the AE network, which was explained by a single outlying study contributing the only direct evidence for one of the nodes. 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 EC use. Very few studies reported data on other outcomes or comparisons; hence, evidence for these is limited, with CIs often encompassing both clinically significant harm and benefit. There is high-certainty evidence that ECs with nicotine increase quit rates compared to NRT and moderate-certainty evidence that they increase quit rates compared to ECs without nicotine. Evidence comparing nicotine EC with usual care or no treatment also suggests benefit, but is less certain due to risk of bias inherent in the study design. Confidence intervals were, for the most part, wide for data on AEs, SAEs, and other safety markers, with no evidence for a difference in AEs between nicotine and non-nicotine ECs nor between nicotine ECs and NRT, but low-certainty evidence for increased AEs compared with behavioural support/no support. Overall incidence of SAEs was low across all study arms. We did not detect evidence of serious harm from nicotine EC, but longer, larger studies are needed to fully evaluate EC safety. Our included studies tested regulated nicotine-containing EC; illicit products and/or products containing other active substances (e.g. tetrahydrocannabinol (THC)) may have different harm profiles. The main limitation of the evidence base remains 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 to decision-makers, this is 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.

Lindson N ，Butler AR ，McRobbie H ，Bullen C ，Hajek P ，Wu AD ，Begh R ，Theodoulou A ，Notley C ，Rigotti NA ，Turner T ，Livingstone-Banks J ，Morris T ，Hartmann-Boyce J ... -  《Cochrane Database of Systematic Reviews》