Network meta-analysis: simultaneous meta-analysis of common antiplatelet regimens after transient ischaemic attack or stroke

Drug-Drug Interactions and Synergy: From Pharmacological Models to Clinical Application

This review explores the concept of synergy in pharmacology, emphasizing its importance in optimizing treatment outcomes through the combination of drugs with different mechanisms of action. Synergy, defined as an effect greater than the expected additive effect elicited by individual agents according to specific predictive models, offers a promising approach to enhance therapeutic efficacy while minimizing adverse events. The historical evolution of synergy research, from ancient civilizations to modern pharmacology, highlights the ongoing quest to understand and harness synergistic interactions. Key concepts, such as concentration-response curves, additive effects, and predictive models, are discussed in detail, emphasizing the need for accurate assessment methods throughout translational drug development. Although various mathematical models exist for synergy analysis, selecting the appropriate model and software tools remains a challenge, necessitating careful consideration of experimental design and data interpretation. Furthermore, this review addresses practical considerations in synergy assessment, including preclinical and clinical approaches, mechanism of action, and statistical analysis. Optimizing synergy requires attention to concentration/dose ratios, target site localization, and timing of drug administration, ensuring that the benefits of combination therapy detected bench-side are translatable into clinical practice. Overall, the review advocates for a systematic approach to synergy assessment, incorporating robust statistical analysis, effective and simplified predictive models, and collaborative efforts across pivotal sectors, such as academic institutions, pharmaceutical companies, and regulatory agencies. By overcoming critical challenges and maximizing therapeutic potential, effective synergy assessment in drug development holds promise for advancing patient care. SIGNIFICANCE STATEMENT: Combining drugs with different mechanisms of action for synergistic interactions optimizes treatment efficacy and safety. Accurate interpretation of synergy requires the identification of the expected additive effect. Despite innovative models to predict the additive effect, consensus in drug-drug interactions research is lacking, hindering the bench-to-bedside development of combination therapies. Collaboration among science, industry, and regulation is crucial for advancing combination therapy development, ensuring rigorous application of predictive models in clinical settings.

Clinical outcomes of different revascularization approaches for patients with multi-vessel coronary artery disease: A network meta-analysis

BACKGROUND

As surgical techniques continue to evolve, the optimal approach for revascularizing multi-vessel coronary artery disease (CAD) remains a matter of ongoing debate. Accordingly, our objective was to compare and contrast various surgical techniques utilized in the management of multi-vessel CAD.

METHODS

A systematic literature review was performed using PubMed, Embase, and Cochrane central register of controlled trials from inception to May 2022. Random-effects network meta-analysis was performed for the primary outcome; target vessel revascularization (TVR), and secondary outcomes; mortality, major adverse cardiac and cerebrovascular events, postoperative myocardial infarction, new-onset atrial fibrillation, stroke, new-onset dialysis, in patients undergoing percutaneous coronary intervention (PCI) with a stent, off-pump coronary bypass graft, on-pump coronary artery bypass graft (ONCABG), hybrid coronary revascularization, minimally-invasive coronary artery bypass, or robot-assisted coronary artery bypass (RCAB) surgeries.

RESULTS

A total of 8841 patients were included from 23 studies. The analysis showed that ONCABG had the highest freedom from TVR, with a mean (SD) absolute risk of 0.027 (0.029); although ONCABG was found to be superior to all other methods, it was only significantly better than first-generation stent PCI. While RCAB did not demonstrate significant superiority over other treatments, it showed a greater probability of preventing postoperative complications. Notably, no significant heterogeneity was calculated for any of the reported outcomes.

CONCLUSIONS

ONCABG shows a better rank probability compared to all other techniques for preventing TVR, while RCAB offers greater freedom from most postoperative complications. However, given the absence of randomized controlled trials, these results should be interpreted with caution.

Safety outcomes of anti-platelet therapy post coronary artery bypass graft surgery: A systematic review and network meta-analysis of randomized control trials

BACKGROUND

Antiplatelet therapy is used to decrease the risk of graft failure post coronary artery bypass graft surgery. We aimed to compare dual antiplatelet therapy (DAPT) with monotherapy along with a comparison of Aspirin, Ticagrelor, Aspirin+Ticagrelor (A+T) and Aspirin+Clopidogrel (A+C) to determine the major and minor bleeding risk, risk of postoperative myocardial infarction (MI), stroke, and all-cause mortality (ACM).

METHODS

Randomized Controlled Trials comparing the four groups were included. Odds ratio (OR) and Absolute Risk (AR) were employed to assess the mean and standard deviation (SD) with 95% confidence intervals (CI). The Bayesian random-effects model was used for statistical analysis. Risk difference and Cochran Q tests were used to calculate rank probability (RP) and heterogeneity, respectively.

RESULTS

We included 10 trials, consisting of 21 arms and 3926 patients. For the risk of major and minor bleed, A + T and Ticagrelor showed the lowest mean value of 0.040 (0.043) and 0.067 (0.073), respectively, and the highest RP of being the safest group. While a direct comparison between DAPT and monotherapy resulted in an OR of 0.57 [0.34, 0.95] for the risk of minor bleed. A + T was found to have the highest RP and the lowest mean value in terms of ACM, MI, and stroke.

CONCLUSION

No significant difference was found between monotherapy or dual-antiplatelet therapy for the major bleeding risk safety outcome, however DAPT was found to have a significantly higher rate of minor bleeding complications post-CABG. DAPT should be considered as the antiplatelet modality of choice post-CABG.

Diagnostic accuracy of tests for tuberculous pericarditis: A network meta-analysis

Tuberculous pericarditis (TBP) is a relatively uncommon but potentially fatal extrapulmonary manifestation of tuberculosis. Despite its severity, there is no universally accepted gold standard diagnostic test for TBP currently. The objective of this study is to compare the diagnostic accuracy of the most commonly used tests in terms of specificity, sensitivity, negative predictive value (NPV), and positive predictive value (PPV), and provide a summary of their diagnostic accuracies. A comprehensive literature review was performed using Scopus, MEDLINE, and Cochrane central register of controlled trials, encompassing studies published from start to April 2022. Studies that compared Interferon Gamma Release Assay (IGRA), Xpert MTB/RIF, Adenosine Deaminase levels (ADA), and Smear Microscopy (SM) were included in the analysis. Bayesian random-effects model was used for statistical analysis and mean and standard deviation (SD) with 95% confidence intervals were calculated using the absolute risk (AR) and odds ratio (OR). Rank probability and heterogeneity were determined using risk difference and Cochran Q test, respectively. Sensitivity and specificity were evaluated using true negative, true positive, false positive, and false negative rates. Area under the receiver operating characteristic (AUROC) was calculated for mean and standard error. A total of seven studies comprising 16 arms and 618 patients were included in the analysis. IGRA exhibited the highest mean (SD) sensitivity of 0.934 (0.049), with a high rank probability of 87.5% for being the best diagnostic test, and the AUROC was found to be 94.8 (0.36). On the other hand, SM demonstrated the highest mean (SD) specificity of 0.999 (0.011), with a rank probability of 99.5%, but a leave-one-out analysis excluding SM studies revealed that Xpert MTB/RIF ranked highest for specificity, with a mean (SD) of 0.962 (0.064). The diagnostic tests compared in our study exhibited similar high NPV, while ADA was found to have the lowest PPV among the evaluated methods. Further research, including comparative studies, should be conducted using a standardized cutoff value for both ADA levels and IGRA to mitigate the risk of threshold effect and minimize bias and heterogeneity in data analysis.

A network meta-analysis for efficacies and toxicities of different concurrent chemoradiotherapy regimens in the treatment of locally advanced non-small cell lung cancer

Background

Concurrent chemoradiotherapy (CCRT) has become the cornerstone of treatment for patients with locally advanced non-small cell lung cancer (LA-NSCLC). The aim of this study was to compare the efficacies and toxicities of different CCRT regimens in the treatment of LA-NSCLC by adopting a network meta-analysis (NMA).

Methods

An exhaustive search of PubMed, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL) was conducted to identify relevant studies from inception to October 1, 2020. Direct and indirect evidence was combined to calculate the odds radios (ORs) and 95% confidence intervals (CIs), as well as to plot the surface under the cumulative ranking (SUCRA) curves. Cluster analyses were adopted to compare the efficacies and toxicities of different CCRT regimens according to the similarity of 2 variables. Publication bias was detected by comparison-adjusted funnel plots.

Results

Twenty-two studies were enrolled in this NMA, including 18 regimens: CCRT (cisplatin + etoposide), CCRT (carboplatin + paclitaxel), CCRT (pemetrexed + carboplatin), CCRT (pemetrexed + cisplatin), CCRT (docetaxel + cisplatin), CCRT (S-1 + cisplatin), CCRT (mitomycin + vindesine + cisplatin), CCRT (cisplatin + vinorelbine), CCRT (cisplatin), CCRT (etoposide + cisplatin + amifostine), RT, CCRT (5-FU), CCRT (paclitaxel + cisplatin), CCRT (irinotecan + carboplatin), CCRT (nedaplatin), CCRT (carboplatin + etoposide), CCRT (paclitaxel), and CCRT (carboplatin). The results indicated that the regimens with CCRT (cisplatin + etoposide), CCRT (carboplatin + paclitaxel), CCRT (pemetrexed + cisplatin), CCRT (S-1 + cisplatin), and CCRT (cisplatin + vinorelbine) had relatively better efficacies compared with other regimens. As for toxicities of different CCRT regimens, the CCRT (carboplatin + paclitaxel), CCRT (pemetrexed + cisplatin), and CCRT (docetaxel + cisplatin) were relatively lower.

Conclusions

Our study demonstrated that CCRT (pemetrexed + cisplatin) and CCRT (carboplatin + paclitaxel) might be the best options for the treatment of LA-NSCLC, and CCRT (pemetrexed + cisplatin) had the highest 3-year overall survival (OS) rate.

Termination of seizures in the paediatric age group, best benzodiazepine and route of administration: A network meta-analysis

This network meta-analysis aims to compare various benzodiazepines and their route of administration using the data published exclusively in randomized controlled trials (RCTs). Two thousand two hundred sixty-three children presenting with an episode of seizure to ER or to a paramedic where they were administered a benzodiazepine as the first-line treatment were included. All the outcomes were measured for their mean with 95% CI and rank probability. The primary outcome was the number of successful seizure cessation. Secondary outcomes were the time interval between drug administration and seizure cessation, the time interval between patient arrival and seizure cessation and the number of episodes of seizure recurrence after drug administration. For the number of successful cessations, intramuscular midazolam showed the highest mean and best rank probability with a value of .881 (.065) and 57.9%, respectively. For the time of cessation, both intravenous lorazepam (IVL) and intravenous diazepam showed a mean of 3.30 (1.30) with IVL having the highest rank probability of 32%. For total time for cessation, intranasal midazolam showed the best mean and rank probability with a value of 4.3 (1.1) and 55%, respectively. Buccal midazolam showed the lowest mean with a value of .106 (.084) for rate of recurrence. Although there was no significant difference between the treatments, but based on the rank probability, IVL shows more promising results for patients who already have an established intravenous line, and for patients presenting in the ER without an intravenous line, the first line of treatment should be INM as it shows the highest rank probability in total time with second-highest successful cessation rate.

Risk of hepatocellular carcinoma in antiviral treatment-naïve chronic hepatitis B patients treated with entecavir or tenofovir disoproxil fumarate: a network meta-analysis

BACKGROUND

Long-term antiviral treatments are associated with a significantly lower hepatocellular carcinoma (HCC) incidence in chronic hepatitis B (CHB) patients by reducing HBV DNA concentrations. However, it is still controversial whether antiviral strategies affect HCC development in antiviral treatment-naïve CHB patients. This study aimed to estimate the incidence of HCC in antiviral treatment-naïve CHB patients who were treated with Entecavir (ETV) and Tenofovir Disoproxil Fumarate (TDF) and compare the efficacy of two treatment regimens in HCC reduction.

METHODS

The PubMed, Embase, China National Knowledge Infrastructure, and Wanfang databases were systematically searched until June 24, 2021. The pooled incidence and 95% confidence interval of HCC were calculated by the Freeman-Tukey double arcsine transformation method. The efficacies of ETV and TDF treatments in HCC reduction were compared through a network meta-analysis.

RESULTS

A total of 27 studies were identified as eligible for this systematic review. The incidence densities in the ETV and TDF treatment groups were 2.78 (95% CI: 2.21-3.40) and 2.59 (95% CI: 1.51-3.96) per 100 persons-year among patients with preexisting cirrhosis and 0.49 (95% CI: 0.32-0.68) and 0.30 (95% CI: 0.06-0.70) per 100 persons-year among patients without preexisting cirrhosis. As the proportion of CHB patients with preexisting cirrhosis increased, the incidence density of HCC also increased gradually. Compared with other Nucleos(t)ide analogs (NAs) treatments, ETV and TDF treatments significantly lowered the risk of HCC, with hazard ratios (HRs) of 0.60 (95% CI: 0.40-0.90) and 0.56 (95% CI: 0.35-0.89), respectively. However, there was no difference in the incidence density of HCC between ETV and TDF treatments (HR = 0.92, 95% CI: 0.71-1.20) regardless of preexisting cirrhosis.

CONCLUSION

ETV and TDF treatments were associated with significantly lower risks of HCC than other NAs treatments. However, no difference was observed between ETV and TDF treatments in the risk of HCC development regardless of preexisting cirrhosis among treatment-naïve CHB patients.

Antiplatelet drugs for secondary prevention in patients with ischemic stroke or transient ischemic attack: a systematic review and network meta-analysis

BACKGROUND

Antiplatelet drugs may prevent recurrent ischemic events after ischemic stroke but their relative effectiveness and harms still need to be clarified. Within this network meta-analysis we aimed to summarize the current evidence for using antiplatelet drugs for secondary stroke prevention.

METHODS

We searched MEDLINE, EMBASE and CENTRAL up to September 2020. Randomized controlled trials (RCTs) assessing antiplatelet drugs for secondary stroke prevention were included. We did pairwise meta-analyses and network meta-analyses using random-effects models. Primary outcomes were all strokes (ischemic or hemorrhagic) and all-cause mortality.

RESULTS

The review included 57 RCTs, 50 (n = 165,533 participants) provided data for the meta-analyses. Compared to placebo/no treatment, moderate to high-confidence evidence indicated that cilostazol, clopidogrel, dipyridamole + aspirin, ticagrelor, ticlopidine, and aspirin ≤ 150 mg/day significantly reduced the risk of all strokes (odds ratios, ORs and absolute risk difference, ARD): cilostazol 0.51 (95 % confidence interval, CI, 0.37 to 0.71; 3.6 % fewer), clopidogrel 0.63 (95 % CI, 0.49 to 0.79; 2.7 % fewer), dipyridamole + aspirin 0.65 (95 % CI, 0.55 to 0.78; 2.5 % fewer), ticagrelor 0.68 (95 % CI, 0.50 to 0.93; 2.3 % fewer), ticlopidine 0.74 (95 % CI 0.59 to 0.93; 1.9 % fewer), aspirin ≤ 150 mg/day 0.79 (95 % CI, 0.66 to 0.95; 1.5 % fewer). Aspirin > 150 mg/day and the combinations clopidogrel/aspirin, ticagrelor/aspirin, also decrease all strokes but increase the risk of hemorrhagic events. Only aspirin > 150 mg/day significantly reduced all-cause mortality (OR 0.86, 95 % CI 0.76 to 0.97; ARD 0.9 %, 95 %CI 1.5-0.2 % fewer, moderate confidence). Compared to aspirin ≤ 150 mg/day, clopidogrel significantly reduced the risk of all strokes, cardiovascular events, and intracranial hemorrhage outcomes. Cilostazol also appeared to provide advantages but data are limited to the Asian population.

CONCLUSIONS

Considering the benefits and harms ratio, cilostazol, clopidogrel, dipyridamole + aspirin, ticagrelor, ticlopidine, and aspirin ≤ 150 mg/day appear to be the best choices as antiplatelet drugs for secondary prevention of patients with ischemic stroke or TIA.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020159896 .

Impact of multiple cardiovascular medications on mortality after an incidence of ischemic stroke or transient ischemic attack

BACKGROUND

To manage the risk factors and to improve clinical outcomes, patients with stroke commonly receive multiple cardiovascular medications. However, there is a lack of evidence on the optimum combination of medication therapy in the primary care setting after ischemic stroke. Therefore, this study aimed to investigate the effect of multiple cardiovascular medications on long-term survival after an incident stroke event (ischemic stroke or transient ischemic attack (TIA)).

METHODS

This study consisted of 52,619 patients aged 45 and above with an incident stroke event between 2007 and 2016 in The Health Improvement Network database. We estimated the risk of all-cause mortality in patients with multiple cardiovascular medications versus monotherapy using a marginal structural model.

RESULTS

During an average follow-up of 3.6 years, there were 9230 deaths (7635 in multiple cardiovascular medication groups and 1595 in the monotherapy group). Compared with patients prescribed monotherapy only, the HRs of mortality were 0.82 (95% CI 0.75-0.89) for two medications, 0.65 (0.59-0.70) for three medications, 0.61 (0.56-0.67) for four medications, 0.60 (0.54-0.66) for five medications and 0.66 (0.59-0.74) for ≥ six medications. Patients with any four classes of antiplatelet agents (APAs), lipid-regulating medications (LRMs), angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs), beta-blockers, diuretics and calcium channel blockers (CCBs) had the lowest risk of mortality (HR 0.51, 95% CI 0.46-0.57) versus any one class. The combination containing APAs, LRMs, ACEIs/ARBs and CCBs was associated with a 61% (95% CI 53-68%) lower risk of mortality compared with APAs alone.

CONCLUSION

Our results suggested that combination therapy of four or five cardiovascular medications may be optimal to improve long-term survival after incident ischemic stroke or TIA. APAs, LRMs, ACEIs/ARBs and CCBs were the optimal constituents of combination therapy in the present study.

The impact of covariance priors on arm-based Bayesian network meta-analyses with binary outcomes

Bayesian analyses with the arm-based (AB) network meta-analysis (NMA) model require researchers to specify a prior distribution for the covariance matrix of the treatment-specific event rates in a transformed scale, for example, the treatment-specific log-odds when a logit transformation is used. The commonly used conjugate prior for the covariance matrix, the inverse-Wishart (IW) distribution, has several limitations. For example, although the IW distribution is often described as noninformative or weakly informative, it may in fact provide strong information when some variance components are small (eg, when the standard deviation of study-specific log-odds of a treatment is smaller than 1/2), as is common in NMAs with binary outcomes. In addition, the IW prior generally leads to underestimation of correlations between treatment-specific log-odds, which are critical for borrowing strength across treatment arms to estimate treatment effects efficiently and to reduce potential bias. Alternatively, several separation strategies (ie, separate priors on variances and correlations) can be considered. To study the IW prior's impact on NMA results and compare it with separation strategies, we did simulation studies under different missing-treatment mechanisms. A separation strategy with appropriate priors for the correlation matrix and variances performs better than the IW prior, and should be recommended as the default vague prior in the AB NMA approach. Finally, we reanalyzed three case studies and illustrated the importance, when performing AB-NMA, of sensitivity analyses with different prior specifications on variances.

Empirical evaluation of SUCRA-based treatment ranks in network meta-analysis: quantifying robustness using Cohen's kappa

OBJECTIVE

To provide a framework for quantifying the robustness of treatment ranks based on Surface Under the Cumulative RAnking curve (SUCRA) in network meta-analysis (NMA) and investigating potential factors associated with lack of robustness.

METHODS

We propose the use of Cohen's kappa to quantify the agreement between SUCRA-based treatment ranks estimated through NMA of a complete data set and a subset of it. We illustrate our approach using five published NMA data sets, where robustness was assessed by removing studies one at a time.

RESULTS

Overall, SUCRA-based treatment ranks were robust to individual studies in the five data sets we considered. We observed more incidences of disagreement between ranks in the networks with larger numbers of treatments. Most treatments moved only one or two ranks up or down. The lowest quadratic weighted kappa estimate observed across all networks was in the network with the smallest number of treatments (4), where weighted kappa=40%. In the network with the largest number of treatments (12), the lowest observed quadratic weighted kappa=89%, reflecting a small shift in this network's treatment ranks overall. Preliminary observations suggest that a study's size, the number of studies making a treatment comparison, and the agreement of a study's estimated treatment effect(s) with those estimated by other studies making the same comparison(s) may explain the overall robustness of treatment ranks to studies.

CONCLUSIONS

Investigating robustness or sensitivity in an NMA may reveal outlying rank changes that are clinically or policy-relevant. Cohen's kappa is a useful measure that permits investigation into study characteristics that may explain varying sensitivity to individual studies. However, this study presents a framework as a proof of concept and further investigation is required to identify potential factors associated with the robustness of treatment ranks using more extensive empirical evaluations.

Antiplatelet Therapy After Noncardioembolic Stroke

Background and Purpose- We assessed the efficacy and safety of antiplatelet agents after noncardioembolic stroke or transient ischemic attack and examined how these vary according to patients' demographic and clinical characteristics. Methods- We did a network meta-analysis (NMA) of data from 6 randomized trials of the effects of commonly prescribed antiplatelet agents in the long-term (≥3 months) secondary prevention of noncardioembolic stroke or transient ischemic attack. Individual patient data from 43 112 patients were pooled and reanalyzed. Main outcomes were serious vascular events (nonfatal stroke, nonfatal myocardial infarction, or vascular death), major bleeding, and net clinical benefit (serious vascular event or major bleeding). Subgroup analyses were done according to age, sex, ethnicity, hypertension, qualifying diagnosis, type of vessel involved (large versus small vessel disease), and time from qualifying event to randomization. Results- Aspirin/dipyridamole combination (RR_NMA-adj, 0.83; 95% CI, 0.74-0.94) significantly reduced the risk of vascular events compared with aspirin, as did clopidogrel (RR_NMA-adj, 0.88; 95% CI, 0.78-0.98), and aspirin/clopidogrel combination (RR_NMA-adj, 0.83; 95% CI, 0.71-0.96). Clopidogrel caused significantly less major bleeding and intracranial hemorrhage than aspirin, aspirin/dipyridamole combination, and aspirin/clopidogrel combination. Aspirin/clopidogrel combination caused significantly more major bleeding than aspirin, aspirin/dipyridamole combination, and clopidogrel. Net clinical benefit was similar for clopidogrel and aspirin/dipyridamole combination (RR_NMA-adj, 0.99; 95% CI, 0.93-1.05). Subgroup analyses showed no heterogeneity of treatment effectiveness across prespecified subgroups. The excess risk of major bleeding associated with aspirin/clopidogrel combination compared with clopidogrel alone was higher in patients aged <65 years than it was in patients ≥65 years (RR_NMA-adj, 3.9 versus 1.7). Conclusions- Results favor clopidogrel and aspirin/dipyridamole combination for long-term secondary prevention after noncardioembolic stroke or transient ischemic attack, regardless of patient characteristics. Aspirin/clopidogrel combination was associated with a significantly higher risk of major bleeding compared with other antiplatelet regimens.

Efficacy of different antidiabetic drugs based on metformin in the treatment of type 2 diabetes mellitus: A network meta-analysis involving eight eligible randomized-controlled trials

Diabetes mellitus is one of the most prevalent metabolic diseases globally and it is increasing in prevalence. It is one of the most expensive diseases with respect to total health care costs per patient as a result of its chronic nature and its severe complications. To provide a more effective treatment of type 2 diabetes mellitus (T2DM), this study aims to compare different efficacies of six kinds of hypoglycemic drugs based on metformin, including glimepiride, pioglitazone, exenatide, glibenclamide, rosiglitazone, and vildagliptin, in T2DM by a network meta-analysis that were verified by randomized-controlled trials (RCTs). Eight eligible RCT in consistency with the aforementioned six hypoglycemic drugs for T2DM were included. The results of network meta-analysis demonstrated that the exenatide + metformin and vildagliptin + metformin regimens presented with better efficacy. Patients with T2DM with unsatisfactory blood glucose control based on diet control, proper exercise, and metformin treatment were included. The original regimen and dose of medication were unchanged, followed by the addition of glimepiride, pioglitazone, exenatide, glibenclamide, rosiglitazone, and vildagliptin. The results of RCTs showed that all these six kinds of drugs reduced the HbA1c level. Compared with other regimens, exenatide + metformin reduced fasting plasma glucose (FPG), fasting plasma insulin (FPI), total cholesterol (TC), and homeostasis model assessment insulin resistance index (HOMA-IR) levels, but increased the high-density lipoprotein (HDL) level; vildagliptin + metformin decreased FPI and low-density lipoprotein (LDL) levels; glibenclamide + metformin decreased the FPG level, but promoted HDL; and glimepiride + metformin decreased the TC level and rosiglitazone + metformin reduced the LDL level. Our findings indicated that exenatide + metformin and vildagliptin + metformin have better efficacy in T2DM since they can improve insulin sensitivity.

Cancer Event Rate and Mortality with Thienopyridines: A Systematic Review and Meta-Analysis

INTRODUCTION

Thienopyridines are a class of antiplatelet drugs widely used in cardiovascular disease prevention and treatment. A recent concern has come to light regarding the safety of thienopyridines because of the possible risk of malignancy. We therefore performed a systematic review and meta-analysis to evaluate the association between thienopyridine exposure and malignancy.

METHODS

We searched the MEDLINE and EMBASE databases in March 2016 for studies that evaluated incident cancer and cancer mortality with and without exposure to thienopyridines. Relevant studies were identified, and data were extracted and analysed using random-effects meta-analysis.

RESULTS

A total of nine studies (six randomised controlled trials and three cohort studies) that included 282,084 participants were included. The cancer event rate with clopidogrel and prasugrel was 3.25% and 1.58% respectively. When compared with standard aspirin or placebo, thienopyridines are not significantly associated with cancer mortality and event rate (odds ratio [OR] 1.12, 95% confidence interval [CI] 0.80-1.56, n = 3; and OR 0.92, 95% CI 0.52-1.64, n = 2, respectively. Further analyses examining clopidogrel showed no significant association with cancer event rate or malignancy-related death. When comparing prasugrel with clopidogrel, no significant association was noted for cancer event rate (OR 1.10, 95% CI 0.89-1.37, n = 2]. Subanalyses according to cancer location showed that thienopyridines are not significantly associated with malignancy mortality and/or incidence.

CONCLUSIONS

Our results suggest that there is currently insufficient evidence to suggest that thienopyridine exposure is associated with an increased risk of cancer event rate or mortality.

Performing Arm-Based Network Meta-Analysis in R with the pcnetmeta Package

Network meta-analysis is a powerful approach for synthesizing direct and indirect evidence about multiple treatment comparisons from a collection of independent studies. At present, the most widely used method in network meta-analysis is contrast-based, in which a baseline treatment needs to be specified in each study, and the analysis focuses on modeling relative treatment effects (typically log odds ratios). However, population-averaged treatment-specific parameters, such as absolute risks, cannot be estimated by this method without an external data source or a separate model for a reference treatment. Recently, an arm-based network meta-analysis method has been proposed, and the R package pcnetmeta provides user-friendly functions for its implementation. This package estimates both absolute and relative effects, and can handle binary, continuous, and count outcomes.

Efficacy and toxicity of different concurrent chemoradiotherapy regimens in the treatment of advanced cervical cancer: A network meta-analysis

OBJECTIVE

The aim of this study was to compare the efficacy and toxicity of different concurrent chemoradiotherapy (CCRT) regimens in the treatment of advanced cervical cancer (CC) by adopting a network meta-analysis.

METHODS

We searched PubMed and Cochrane Library from the inception of these databases to September 2016, and all cohort studies (CSs) related to different CCRT regimens in the treatment of CC were included. A network analysis was adopted to compare the combination of direct and indirect evidence, to analyze the odds ratio (OR), and to draw a surface under the cumulative ranking curve of the efficacy and toxicity of different CCRT regimens for CC. Cluster analyses were used to group each category based on similar treatment regimens.

RESULTS

Nineteen CSs were enrolled in this network meta-analysis, including 12 CCRT regimens (radiotherapy [RT], CCRT [cisplatin], CCRT [vinorelbine], CCRT [paclitaxel], CCRT [hydroxyurea], CCRT [cisplatin + FU], CCRT [cisplatin + gemcitabine], CCRT [cisplatin + docetaxel], CCRT [cisplatin + paclitaxel], CCRT [cisplatin + amifostine], CCRT [cisplatin + FU + hydroxyurea], and CCRT [cisplatin + vincristine + bleomycin]). The results of the network meta-analysis showed that regarding efficacy, the overall response rate of CCRT (cisplatin + docetaxel) was higher than RT, and the 5-year overall survival (OS) rate of CCRT (cisplatin + FU + hydroxyurea) was relatively higher than CCRT (hydroxyurea). As for toxicity, CCRT (cisplatin) had a lower incidence of leukopenia than CCRT (hydroxyurea), CCRT (cisplatin + FU) and CCRT (cisplatin + paclitaxel), and the incidences of diarrhea and vomiting in CCRT (cisplatin) were lower than those in CCRT (cisplatin + gemcitabine). Additionally, the cluster analysis showed that CCRT (cisplatin) had relatively lower incidences of both hematotoxicity and gastrointestinal toxicity, and CCRT (paclitaxel) had lower gastrointestinal toxicity than other regimens.

CONCLUSION

Our study demonstrated that CCRT (cisplatin + docetaxel) might be the best choice of CCRT regimens in the treatment of CC, and the 5-year OS rate of CCRT (cisplatin + FU + hydroxyurea) might be the highest among these different regimens. CCRT (cisplatin) might have the lowest toxicity among all the CCRT regimens.

The Impact of Excluding Trials from Network Meta-Analyses - An Empirical Study

Network meta-analysis (NMA) expands the scope of a conventional pairwise meta-analysis to simultaneously compare multiple treatments, which has an inherent appeal for clinicians, patients, and policy decision makers. Two recent reports have shown that the impact of excluding a treatment on NMAs can be substantial. However, no one has assessed the impact of excluding a trial from NMAs, which is important because many NMAs selectively include trials in the analysis. This article empirically examines the impact of trial exclusion using both the arm-based (AB) and contrast-based (CB) approaches, by reanalyzing 20 published NMAs involving 725 randomized controlled trials and 449,325 patients. For the population-averaged absolute risk estimates using the AB approach, the average fold changes across all networks ranged from 1.004 (with standard deviation 0.004) to 1.072 (with standard deviation 0.184); while the maximal fold changes ranged from 1.032 to 2.349. In 12 out of 20 NMAs, a 1.20-fold or larger change is observed in at least one of the population-averaged absolute risk estimates. In addition, while excluding a trial can substantially change the estimated relative effects (e.g., log odds ratios), there is no systematic difference in terms of changes between the two approaches. Changes in treatment rankings are observed in 7 networks and changes in inconsistency are observed in 3 networks. We do not observe correlations between changes in treatment effects, treatment rankings and inconsistency. Finally, we recommend rigorous inclusion and exclusion criteria, logical study selection process, and reasonable network geometry to ensure robustness and generalizability of the results of NMAs.

The efficacy and safety of H1-antihistamine versus Montelukast for allergic rhinitis: A systematic review and meta-analysis

PURPOSE

In order to verify the differences of effectiveness and safety between SAHs and Montelukast, and to find out potential uncared-for problems, we performed a systematic review and Meta-analysis to proceed a qualitative describe and quantitative assessment.

METHODS

We searched the databases of Pubmed, the Cochrane Library, Nature and Science as well as Wanfang data and CNKI from 2000 to March 2016, using key words "Montelukast SAH" or "H1-antihistamine Montelukast", or "Loratadine Montelukast", or "Desloratadine Montelukast", or "Levocetirizine Montelukast", or "Cetirizen Montelukast", or "Fexofenadine Montelukast". And also we included studies through relevant citations in related literature. Meta-analysis and bias of risk were performed. We analyzed Heterogeneity and publish bias as well.

RESULT

Montelukast seems more effective in nighttime symptoms compare with SAHs (P=0.008, MD=-0.04, 95%CI: -0.08, -0.01). No significant difference was found between Montelukast and SAHs in CSS (P=0.10, MD=0.03, 95%CI: -0.01, 0.07). Montelukast and SAHs combined therapy was more effective than Montelukast DNSS (P=0.0006, MD=0.15, 95%CI: 0.07, 0.24) but not in CSS (P=0.04, MD=0.08, 95%CI: 0.00, 0.15; Bonferroni correction α=0.017).

CONCLUSION

Montelukast has a significant influence in improving patients' nasal symptoms quality of live but is not as effective as SAHs, and may have a slight advantage over SAHs in relieving nighttime symptoms significantly. Combined therapy is more effective in improving patients' day time symptom than Montelukast. Probably, patients might have a lower asthenia incidence rate when using Montelukas.

Sensitivity to Excluding Treatments in Network Meta-analysis

Network meta-analysis of randomized controlled trials is increasingly used to combine both direct evidence comparing treatments within trials and indirect evidence comparing treatments across different trials. When the outcome is binary, the commonly used contrast-based network meta-analysis methods focus on relative treatment effects such as odds ratios comparing two treatments. As shown in a recent report, when using contrast-based network meta-analysis, the impact of excluding a treatment in the network can be substantial, suggesting a methodological limitation. In addition, relative treatment effects are sometimes not sufficient for patients to make decisions. For example, it can be challenging for patients to trade off efficacy and safety for two drugs if they only know the relative effects, not the absolute effects. A recently proposed arm-based network meta-analysis, based on a missing-data framework, provides an alternative approach. It focuses on estimating population-averaged treatment-specific absolute effects. This article examines the influence of treatment exclusion empirically using 14 published network meta-analyses, for both arm- and contrast-based approaches. The difference between these two approaches is substantial, and it is almost entirely due to single-arm trials. When a treatment is removed from a contrast-based network meta-analysis, it is necessary to exclude other treatments in two-arm studies that investigated the excluded treatment; such exclusions are not necessary in arm-based network meta-analysis, leading to substantial gain in performance.

Antiplatelet regimens in the long-term secondary prevention of transient ischaemic attack and ischaemic stroke: an updated network meta-analysis

OBJECTIVE

To examine the comparative efficacy and safety of different antiplatelet regimens in patients with prior non-cardioembolic ischaemic stroke or transient ischaemic attack.

DESIGN

Systematic review and network meta-analysis.

DATA SOURCES

As on 31 March 2015, all randomised controlled trials that investigated the effects of antiplatelet agents in the long-term (≥ 3 months) secondary prevention of non-cardioembolic transient ischaemic attack or ischaemic stroke were searched and identified.

OUTCOME MEASURES

The primary outcome measure of efficacy was serious vascular events (non-fatal stroke, non-fatal myocardial infarction and vascular death). The outcome measure of safety was any bleeding.

RESULTS

A total of 36 randomised controlled trials (82,144 patients) were included. Network meta-analysis showed that cilostazol was significantly more effective than clopidogrel (OR 0.77, 95% credible interval 0.60-0.98) and low-dose (75-162 mg daily) aspirin (0.69, 0.55-0.86) in the prevention of serious vascular events. Aspirin (50 mg daily) plus dipyridamole (400 mg daily) and clopidogrel reduced the risk of serious vascular events compared with low-dose aspirin; however, the difference was not statistically significant. Furthermore, low-dose aspirin was as effective as higher daily doses. Cilostazol was associated with a significantly lower bleeding risk than most of the other regimens. Moreover, aspirin plus clopidogrel was associated with significantly more haemorrhagic events than other regimens. Direct comparisons showed similar results as the network meta-analysis.

CONCLUSIONS

Cilostazol was significantly more effective than aspirin and clopidogrel alone in the long-term prevention of serious vascular events in patients with prior non-cardioembolic ischaemic stroke or transient ischaemic attack. Cilostazol was associated with a significantly lower bleeding risk than low-dose aspirin (75-162 mg daily) and aspirin (50 mg daily) plus dipyridamole (400 mg daily). Low-dose aspirin was as effective as higher daily doses. However, further large, randomised, controlled, head-to-head trials are needed, especially in non-Asian ethnic groups.

Long-Term Antiplatelet Mono- and Dual Therapies After Ischemic Stroke or Transient Ischemic Attack: Network Meta-Analysis

BACKGROUND

The latest guidelines do not make clear recommendations on the selection of antiplatelet therapies for long-term secondary prevention of stroke. We aimed to integrate the available evidence to create hierarchies of the comparative efficacy and safety of long-term antiplatelet therapies after ischemic stroke or transient ischemic attack.

METHODS AND RESULTS

We performed a network meta-analysis of randomized controlled trials to compare 11 antiplatelet therapies in patients with ischemic stroke or transient ischemic attack. In December 2014, we searched Medline, Embase, and the Cochrane Library database for trials. The search identified 24 randomized controlled trials including a total of 85 667 patients with antiplatelet treatments for at least 1 year. Cilostazol significantly reduced stroke recurrence in comparison with aspirin (odds ratio 0.66, 95% credible interval 0.44 to 0.92) and dipyridamole (odds ratio 0.57, 95% credible interval 0.34 to 0.95), respectively. Cilostazol also significantly reduced intracranial hemorrhage compared with aspirin, clopidogrel, terutroban, ticlopidine, aspirin plus clopidogrel, and aspirin plus dipyridamole. Aspirin plus clopidogrel could not significantly reduce stroke recurrence compared with monotherapies but caused significantly more major bleeding than all monotherapies except terutroban. The pooled estimates did not change materially in the sensitivity analyses of the primary efficacy outcome.

CONCLUSIONS

Long-term monotherapy was a better choice than long-term dual therapy, and cilostazol had the best risk-benefit profile for long-term secondary prevention after stroke or transient ischemic attack. More randomized controlled trials in non-East Asian patients are needed to determine whether long-term use of cilostazol is the best option for the prevention of recurrent stroke.

Accounting for correlation in network meta-analysis with multi-arm trials

Multi-arm trials (trials with more than two arms) are particularly valuable forms of evidence for network meta-analysis (NMA). Trial results are available either as arm-level summaries, where effect measures are reported for each arm, or as contrast-level summaries, where the differences in effect between arms compare with the control arm chosen for the trial. We show that likelihood-based inference in both contrast-level and arm-level formats is identical if there are only two-arm trials, but that if there are multi-arm trials, results from the contrast-level format will be incorrect unless correlations are accounted for in the likelihood. We review Bayesian and frequentist software for NMA with multi-arm trials that can account for this correlation and give an illustrative example of the difference in estimates that can be introduced if the correlations are not incorporated. We discuss methods of imputing correlations when they cannot be derived from the reported results and urge trialists to report the standard error for the control arm even if only contrast-level summaries are reported. Copyright © 2012 John Wiley & Sons, Ltd.

Efficacy and Safety of HER2-Targeted Agents for Breast Cancer with HER2-Overexpression: A Network Meta-Analysis

BACKGROUND

Clinical trials of human epidermal growth factor receptor 2 (HER2)-targeted agents added to standard treatment have been efficacious for HER2-positive (HER2+) advanced breast cancer. To our knowledge, no meta-analysis has evaluated HER2-targeted therapy including trastuzumab emtansine (T-DM1) and pertuzumab for HER2-positive breast caner and ranked the targeted treatments. We performed a network meta-analysis of both direct and indirect comparisons to evaluate the effect of adding HER2-targeted agents to standard treatment and examined side effects.

METHODS

We performed a Bayesian-framework network meta-analysis of randomized controlled trials to compare 6 HER2-targeted treatment regimens and 1 naïve standard treatment (NST, without any-targeted drugs) in targeted treatment of HER2+ breast cancer in adults. These treatment regimens were T-DM1, LC (lapatinib), HC (trastuzumab), PEC (pertuzumab), LHC (lapatinib and trastuzumab), and PEHC (pertuzumab and trastuzumab). The main outcomes were overall survival and response rates. We also examined side effects of rash, LVEF (left ventricular ejection fraction), fatigue, and gastrointestinal disorders, and performed subgroup analysis for the different treatment regimens in metastatic or advanced breast cancer.

RESULTS

We identified 25 articles of 21 trials, with data for 11,276 participants. T-DM1 and PEHC were more efficient drug regimens with regard to overall survival as compared with LHC, LC, HC and PEC. The incidence of treatment-related rash occurs more frequently in the patients who received LC treatment regimen than PEHC and T-DM1 and HC. In subgroup analysis, T-DM1 was associated with increased overall survival as compared with LC and HC. PEHC was associated with increased overall response as compared with LC, HC, and NST.

CONCLUSIONS

Overall, the regimen of T-DM1 as well as pertuzumab in combination with trastuzumab and docetaxel is efficacious with fewer side effects as compared with other regimens, especially for advanced HER2+ breast cancer.

IMPACT

This study suggests that both T-DM1 and PEHC therapy are potentially and equally useful treatments for HER2+ breast cancer.

Pharmacological interventions for acceleration of the onset time of rocuronium: a meta-analysis

BACKGROUND

Rocuronium is an acceptable alternative when succinylcholine is contraindicated for facilitating the endotracheal intubation. However, the onset time of rocuronium for good intubation condition is still slower than that condition of succinylcholine. This study systematically investigated the most efficacious pharmacological interventions for accelerating the onset time of rocuronium.

METHODS

Medline, Embase, Cochrane Library databases, www.clinicaltrials.gov, and hand searching from the reference lists of identified papers were searched for randomized controlled trials comparing drug interventions with placebo or another drug to shorten the onset time of rocuronium. Statistical analyses were performed using RevMan5.2 and ADDIS 1.16.5 softwares. Mean differences (MDs) with their 95% confidence intervals (95% CIs) were used to analyze the effects of drug interventions on the onset time of rocuronium.

RESULTS

43 randomized controlled trials with 2,465 patients were analyzed. The average onset time of rocuronium was 102.4±24.9 s. Priming with rocuronium [Mean difference (MD) -21.0 s, 95% confidence interval (95% CI) (-27.6 to -14.3 s)], pretreatment with ephedrine [-22.3 s (-29.1 to -15.5 s)], pretreatment with magnesium sulphate [-28.2 s (-50.9 to -5.6 s)] were all effective in reducing the onset time of rocuronium. Statistical testing of indirect comparisons showed that rocuronium priming, pretreatment with ephedrine, and pretreatment with magnesium sulphate had the similar efficacy.

CONCLUSION

Rocuronium priming, pretreatment with ephedrine, and pretreatment with magnesium sulphate were all effective in accelerating the onset time of rocuronium, and furthermore their efficacies were similar. Considering the convenience and efficacy, priming with rocuronium is recommended for accelerating the onset time of rocuronium. However, more strict clinical trials are still needed to reach a more solid conclusion due to the large heterogeneities exist among different studies.

Dual antiplatelet therapy after noncardioembolic ischemic stroke or transient ischemic attack: pros and cons

Dual antiplatelet therapy simultaneously blocks different platelet activation pathways and might thus be more potent at inhibiting platelet activation and more effective at reducing major ischemic vascular events compared to antiplatelet monotherapy. Aspirin plus clopidogrel dual therapy is now the standard therapy for patients with acute coronary syndrome and for those undergoing percutaneous coronary intervention. However, dual antiplatelet therapy carries an increased risk of bleeding. Patients with ischemic stroke or transient ischemic attack (TIA) are generally older and likely to have a fragile cerebrovascular bed, which further increases the risk of systemic major bleeding events and intracranial hemorrhage. Clinical trials and meta-analyses suggest that in comparison to antiplatelet monotherapy, dual antiplatelet therapy initiated early after noncardioembolic ischemic stroke or TIA further reduces the rate of recurrent stroke and major vascular events without significantly increasing the rate of major bleeding events. In contrast, studies of long-term therapy in patients with noncardioembolic ischemic stroke or TIA have yielded inconsistent data regarding the benefit of dual antiplatelet therapy over monotherapy. However, the harm associated with major bleeding events, including intracranial hemorrhage, which is generally more disabling and more fatal than ischemic stroke, is likely to increase with dual antiplatelet therapy. Physicians should carefully assess the benefits and risks of dual antiplatelet therapy versus antiplatelet monotherapy when managing patients with ischemic stroke or TIA.

Combined oral contraceptives: venous thrombosis

BACKGROUND

Combined oral contraceptive (COC) use has been associated with venous thrombosis (VT) (i.e., deep venous thrombosis and pulmonary embolism). The VT risk has been evaluated for many estrogen doses and progestagen types contained in COC but no comprehensive comparison involving commonly used COC is available.

OBJECTIVES

To provide a comprehensive overview of the risk of venous thrombosis in women using different combined oral contraceptives.

SEARCH METHODS

Electronic databases (Pubmed, Embase, Web of Science, Cochrane, CINAHL, Academic Search Premier and ScienceDirect) were searched in 22 April 2013 for eligible studies, without language restrictions.

SELECTION CRITERIA

We selected studies including healthy women taking COC with VT as outcome.

DATA COLLECTION AND ANALYSIS

The primary outcome of interest was a fatal or non-fatal first event of venous thrombosis with the main focus on deep venous thrombosis or pulmonary embolism. Publications with at least 10 events in total were eligible. The network meta-analysis was performed using an extension of frequentist random effects models for mixed multiple treatment comparisons. Unadjusted relative risks with 95% confidence intervals were reported.Two independent reviewers extracted data from selected studies.

MAIN RESULTS

3110 publications were retrieved through a search strategy; 25 publications reporting on 26 studies were included. Incidence of venous thrombosis in non-users from two included cohorts was 0.19 and 0.37 per 1 000 person years, in line with previously reported incidences of 0,16 per 1 000 person years. Use of combined oral contraceptives increased the risk of venous thrombosis compared with non-use (relative risk 3.5, 95% confidence interval 2.9 to 4.3). The relative risk of venous thrombosis for combined oral contraceptives with 30-35 μg ethinylestradiol and gestodene, desogestrel, cyproterone acetate, or drospirenone were similar and about 50-80% higher than for combined oral contraceptives with levonorgestrel. A dose related effect of ethinylestradiol was observed for gestodene, desogestrel, and levonorgestrel, with higher doses being associated with higher thrombosis risk.

AUTHORS' CONCLUSIONS

All combined oral contraceptives investigated in this analysis were associated with an increased risk of venous thrombosis. The effect size depended both on the progestogen used and the dose of ethinylestradiol. Risk of venous thrombosis for combined oral contraceptives with 30-35 μg ethinylestradiol and gestodene, desogestrel, cyproterone acetate and drospirenone were similar, and about 50-80% higher than with levonorgestrel. The combined oral contraceptive with the lowest possible dose of ethinylestradiol and good compliance should be prescribed-that is, 30 μg ethinylestradiol with levonorgestrel.

Secondary prevention of ischaemic stroke

In spite of a documented reduction in incidence in high-income countries over the last decades, stroke is still a leading cause of death and disability worldwide. With the ageing of the population stroke-related economic burden is expected to increase, because of residual disability and its complications, such as cognitive impairment, high risk of falls and fractures, depression and epilepsy. Furthermore, because of the substantial rate of early and long-term vascular recurrences after the first event, secondary prevention after cerebral ischaemia is a crucial issue. This is even more important after minor stroke and transient ischaemic attack (TIA), in order to reduce the risk of potentially more severe and disabling events. To accomplish this aim, acute long-term medical and surgical treatments as well as lifestyle modifications are strongly recommended. However, apart from the well-established indications to thrombolysis, studies in acute phase after a first stroke or TIA are scarce and evidence is lacking. More trials are available for long-term secondary prevention with different classes of drugs, including antithrombotic medications for ischaemic events of arterial and cardiac origin, especially related to atrial fibrillation (antiplatelets and anticoagulants, respectively), lipid lowering agents (mainly statins), blood pressure lowering drugs, surgical and endovascular revascularization procedures.

Comparative efficacy and tolerability of anti-epileptic drugs for refractory focal epilepsy: systematic review and network meta-analysis reveals the need for long term comparator trials

AIMS

To evaluate the comparative efficacy (50% reduction in seizure frequency) and tolerability (premature withdrawal due to adverse events) of anti-epileptic drugs (AEDs) for refractory epilepsy.

METHODS

We searched Cochrane Central Register of Controlled Trials (Cochrane Library 2009, issue 2) including Epilepsy Group's specialized register, MEDLINE (1950 to March 2009), EMBASE (1980 to March 2009), and Current Contents Connect (1998 to March 2009) to conduct a systematic review of published studies, developed a treatment network and undertook a network meta-analysis.

RESULTS

Forty-three eligible trials with 6346 patients and 12 interventions, including placebo, contributed to the analysis. Only three direct drug comparator trials were identified, the remaining 40 trials being placebo-controlled. Conventional random-effects meta-analysis indicated all drugs were superior in efficacy to placebo (overall odds ratio (OR] 3.78, 95% CI 3.14, 4.55) but did not permit firm distinction between drugs on the basis of the efficacy or tolerability. A Bayesian network meta-analysis prioritized oxcarbazepine, topiramate and pregabalin on the basis of short term efficacy. However, sodium valproate, levetiracetam, gabapentin and vigabatrin were prioritized on the basis of short-term efficacy and tolerability, with the caveat that vigabatrin is recognized as being associated with serious visual disturbance with chronic use.

CONCLUSION

Of the wide range of AEDs licensed for the treatment of refractory epilepsy, sodium valproate, levetiracetam and gabapentin demonstrated the best balance of efficacy and tolerability. Until regulators mandate greater use of active comparator trials with longer term follow-up, network meta-analysis provides the only available means to quantify these clinically important parameters.

Comparative efficacy and acceptability of antidepressants in Parkinson's disease: a network meta-analysis

Background

Depression is a common non-motor symptom in patients with Parkinson's disease (PD). There are many kinds of antidepressants being used, such as tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), and Dopamine agonists which are suggested as alternative antidepressants for the treatment of depression in PD. Which one should we choose first? Literatures have shown inconsistent results.

Methods

We conducted a network meta-analysis of randomized controlled trials to compare the efficacy and acceptability of therapeutic methods for the treatment of depression in Parkinson's disease.

Results

We used the odds ratios (OR) as effect size firstly and the results indicated no statistical significance between each compared intervention. Then we used the logarithm of the individual odds ratios as effect size. With efficacy of TCAs as the standard of comparison, the degree of incoherence (a measure of how closely the entire network fits together) was small (ω =  4.824827e-05). The logor were: SSRIs −0.69 (95% CI −1.28– −0.10); Pramipexole −0.73 (−1.71– −0.26); Pergolide −1.97 (−3.67– 0.27); SNRIs −0.86 (−1.86– 0.15); Placebo −1.24 (−1.99– −0.50). With Placebo as the standard of comparison, the logor were: TCAs 1.24 (0.50– 1.99); SSRIs 0.55 (−0.03– 1.13); Pramipexole 0.51 (−0.12– 1.15); Pergolide −0.73 (−2.25– 0.80); SNRIs 0.38 (−0.42– 1.19); TCAs, pramipexole, pergolide and SNRIs showed better profile of acceptability, leading to significant fewer discontinuations than that of SSRIs.

Conclusions

There is insufficient evidence to support antidepressant efficacy for SSRIs, pramipexole, pergolide and SNRIs. TCAs might be the best choice when starting antidepressant treatment in patients of Parkinson's disease because it has the most favorable balance between benefits and acceptability, followed by pramipexole and SNRIs, SSRIs might be the last choice.

The effects of excluding treatments from network meta-analyses: survey

OBJECTIVE

To examine whether the exclusion of individual treatment comparators, including placebo/no treatment, affects the results of network meta-analysis.

DESIGN

Survey of networks with individual trial data.

DATA SOURCES

PubMed and communication with authors of network meta-analyses.

STUDY SELECTION AND METHODS

We included networks that had five or more treatments, contained at least two closed loops, had at least twice as many studies as treatments, and had trial level data available. Investigators abstracted information about study design, participants, outcomes, network geometry, and the exclusion of eligible treatments.

RESULTS

Among 18 eligible networks involving 757 randomised controlled trials with 750 possible treatment comparisons, 11 had upfront decided not to consider all treatment comparators and only 10 included placebo/no treatment nodes. In 7/18 networks, there was at least one node whose removal caused a more than 1.10-fold average relative change in the estimated treatments effects, and switches in the top three treatments were observed in 9/18 networks. Removal of placebo/no treatment caused large relative changes of the treatment effects (average change 1.16-3.10-fold) for four of the 10 networks that had originally included placebo/no treatment nodes. Exclusion of current uncommonly used drugs resulted in substantial changes of the treatment effects (average 1.21-fold) in one of three networks on systemic treatments for advanced malignancies.

CONCLUSION

Excluding treatments in network meta-analyses sometimes can have important effects on their results and can diminish the usefulness of the research to clinicians if important comparisons are missing.

The efficacy and safety of aspirin plus dipyridamole versus aspirin in secondary prevention following TIA or stroke: a meta-analysis of randomized controlled trials

OBJECTIVE

Stroke is becoming a common disease worldwide, and has an increased rate of recurrence yearly after a transient ischemic attack (TIA) or stroke. Aspirin, dipyridamole, clopidogrel and aspirin plus dipyridamole combination therapy have been recommended for the secondary prevention of stroke in Americans.

DESIGN

We performed meta-analyses to assess the effectiveness and safety of combination therapy with aspirin and dipyridamole (A+D) versus aspirin (A) alone in secondary prevention after transient ischemic attack (TIA) or stroke of presumed arterial origin within one week and six months.

DATA SOURCES

Medline, Embase, and the Cochrane Library.

SELECTION OF STUDIES

Eligible studies were completed randomized controlled trials investigating the effect of aspirin plus dipyridamole versus aspirin in patients with previous TIA or stroke.

RESULTS

Five trials involving the use of aspirin and dipyridamole were included, 4318 allocated to A+D and 4304 to A alone. Meta-analysis of trials showed a significant protective effect of reducing or preventing recurrence of stroke (P=0.01), and ischemic event (P=0.003). The statistics showed no significant difference in vascular event, death from all cause and myocardial infarction (P>0.05). There were similarities with all bleeding events, major bleeding and intracranial hemorrhage was significant (P>0.05) between two groups.

CONCLUSIONS

Aspirin plus dipyridamole combination therapy was beneficial in reducing the recurrence of stroke, and did not increase the bleeding event. Hence, aspirin plus dipyridamole combination therapy is effective and safe for the secondary prevention of stroke.

Evaluation of inconsistency in networks of interventions

BACKGROUND

The assumption of consistency, defined as agreement between direct and indirect sources of evidence, underlies the increasingly popular method of network meta-analysis. No evidence exists so far regarding the extent of inconsistency in full networks of interventions or the factors that control its statistical detection.

METHODS

In this paper we assess the prevalence of inconsistency from data of 40 published networks of interventions involving 303 loops of evidence. Inconsistency is evaluated in each loop by contrasting direct and indirect estimates and by employing an omnibus test of consistency for the entire network. We explore whether different effect measures for dichotomous outcomes are associated with differences in inconsistency, and evaluate whether different ways to estimate heterogeneity affect the magnitude and detection of inconsistency.

RESULTS

Inconsistency was detected in from 2% to 9% of the tested loops, depending on the effect measure and heterogeneity estimation method. Loops that included comparisons informed by a single study were more likely to show inconsistency. About one-eighth of the networks were found to be inconsistent. The proportions of inconsistent loops do not materially change when different effect measures are used. Important heterogeneity or the overestimation of heterogeneity was associated with a small decrease in the prevalence of statistical inconsistency.

CONCLUSIONS

The study suggests that changing the effect measure might improve statistical consistency, and that an analysis of sensitivity to the assumptions and an estimator of heterogeneity might be needed before reaching a conclusion about the absence of statistical inconsistency, particularly in networks with few studies.

Indirect and mixed-treatment comparison, network, or multiple-treatments meta-analysis: many names, many benefits, many concerns for the next generation evidence synthesis tool

The ever increasing number of alternative treatment options and the plethora of clinical trials have put systematic reviews and meta-analysis under a new perspective by emphasizing the need to make inferences about competing treatments for the same condition. The statistical component in reviews that compare multiple interventions, network meta-analysis, is the next generation evidence synthesis toolkit which, when properly applied, can serve decision-making better than the established pairwise meta-analysis. The criticism and enthusiasm for network meta-analysis echo those that greeted the advent of simple meta-analysis. The main criticism is associated with the difficulty in evaluating the assumption underlying the statistical synthesis of direct and indirect evidence. In the present article, the assumption of the network meta-analysis are presented using various formulations, the statistical and nonstatistical methodological considerations are elucidated, and the progress achieved in this field is summarized. Throughout, focus is put on highlighting the analogy between the concerns and difficulties that the scientific community had some time ago when advancing from individual trials to their quantitative synthesis via meta-analysis and those currently expressed about the transition from head-to-head meta-analyses to network meta-analysis. Copyright © 2012 John Wiley & Sons, Ltd.

Recommendations for management of patients with carotid stenosis

Stroke is a one of the leading causes of morbidity and mortality in the world. Carotid atherosclerosis is recognized as an important factor in stroke pathophysiology and represents a key target in stroke prevention; multiple treatment modalities have been developed to battle this disease. Multiple randomized trials have shown the efficacy of carotid endarterectomy in secondary stroke prevention. Carotid stenting, a newer treatment option, presents a less invasive alternative to the surgical intervention on carotid arteries. Advances in medical therapy have also enabled further risk reduction in the overall incidence of stroke. Despite numerous trials and decades of clinical research, the optimal management of symptomatic and asymptomatic carotid disease remains controversial. We will attempt to highlight some of the pivotal trials already completed, discuss the current controversies and complexities in the treatment decision-making, and postulate on what likely lies ahead. This paper will highlight the complexities of decision-making optimal treatment recommendations for patients with symptomatic and asymptomatic carotid stenosis.

Second generation endometrial ablation techniques for heavy menstrual bleeding: network meta-analysis

OBJECTIVE

To determine the relative effectiveness of second generation ablation techniques in the treatment of heavy menstrual bleeding.

DESIGN

Network meta-analysis on the primary outcome measures of amenorrhoea, heavy bleeding, and patients' dissatisfaction with treatment.

DATA SOURCES

Nineteen randomised controlled trials (involving 3287 women) were identified through electronic searches of the Cochrane Library, Medline, Embase and PsycINFO databases from inception to April 2011. The reference lists of known relevant articles were searched for further articles. Two reviewers independently selected articles without language restrictions.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials involving second generation endometrial destruction techniques for women with heavy menstrual bleeding unresponsive to medical treatment.

RESULTS

Of the three most commonly used techniques, network meta-analysis showed that bipolar radiofrequency and microwave ablation resulted in higher rates of amenorrhoea than thermal balloon ablation at around 12 months (odds ratio 2.51, 95% confidence interval 1.53 to 4.12, P<0.001; and 1.66, 1.01 to 2.71, P=0.05, respectively), but there was no evidence of a convincing difference between the three techniques in the number of women dissatisfied with treatment or still experiencing heavy bleeding. Compared with bipolar radio frequency and microwave devices, an increased number of women still experienced heavy bleeding after free fluid ablation (2.19, 1.07 to 4.50, P=0.03; and 2.91, 1.23 to 6.88, P=0.02, respectively). Compared with radio frequency ablation, free fluid ablation was associated with reduced rates of amenorrhoea (0.36, 0.19 to 0.67, P=0.004) and increased rates of dissatisfaction (4.79, 1.07 to 21.5, P=0.04). Of the less commonly used devices, endometrial laser intrauterine thermotherapy was associated with increased rates of amenorrhoea compared with all the other devices, while cryoablation led to a reduced rate compared with bipolar radio frequency and microwave.

CONCLUSIONS

Bipolar radio frequency and microwave ablative devices are more effective than thermal balloon and free fluid ablation in the treatment of heavy menstrual bleeding with second generation endometrial ablation devices.

Antithrombotics for secondary prevention of noncardioembolic ischaemic stroke

Antiplatelet therapy is more effective than anticoagulation for the prevention of noncardioembolic ischaemic stroke. The choice of antiplatelet regimen, however, remains contentious. Recent controversies regarding aspirin resistance and the optimal dosing of aspirin, as well as recognition of the variable bioactivation of clopidogrel, have added further confusion to the debate. The American Heart Association (AHA) and American Stroke Association (ASA) recently released their third joint guideline in the past 5 years on secondary stroke prevention. The European Stroke Organisation has published three guidelines on this issue since 2000. These frequent updates have been necessary because of rapidly accumulating data from clinical trials. Careful consideration of the sometimes confusing trial results reveals that the 2011 AHA-ASA guidelines are correct in no longer specifying a 'preferred' antiplatelet regimen from among the choices recently studied. This recommendation does not, however, mean that all antiplatelet regimens should be considered equal. This Review discusses the various antiplatelet regimens, and the trials that led to the rapid evolution of the guidelines for secondary prevention of ischaemic stroke.

A network meta-analysis on the efficacy of serotonin type 3 receptor antagonists used in adults during the first 24 hours for postoperative nausea and vomiting prophylaxis

BACKGROUND

The serotonin type 3 receptor antagonists (5-HT(3) antagonists) ondansetron, granisetron, tropisetron, and dolasetron are potential prophylactic agents for patients with mild to moderate risk of postoperative nausea and vomiting (PONV). A few trials have been conducted to compare the efficacy among 2 to 3 of these 4 agents. However, the comparative efficacy of all four 5-HT(3) antagonists has not yet been quantitatively investigated.

OBJECTIVE

The goal of this study was to investigate whether the 5-HT(3) antagonists--ondansetron, granisetron, tropisetron, and dolasetron-differ in efficacy when used for the prevention of PONV.

METHODS

PubMed and the Cochrane Library were searched for randomized controlled, double-blind studies measuring efficacy in terms of PONV prophylaxis. A Bayesian meta-analysis was conducted using published studies of 5-HT(3) antagonists for PONV prophylaxis. The odds of patients with no PONV and postoperative vomiting (POV) within each study arm 24 hours after surgery were the primary indices of drug efficacy. Data were extracted and analyzed via indirect comparisons using random effects Bayesian models in WinBUGS version 1.4.3.

RESULTS

A total of 85 studies were identified, representing 15,269 patients. The results indicate that granisetron was significantly better than ondansetron (odds ratio [OR] = 1.53 [95% credible interval (CI), 1.15-2.00]) and dolasetron (OR = 1.67 [95% CI, 1.12-2.38]) in preventing PONV. Four antiemetic drugs had comparable efficacy in terms of preventing POV: granisetron showed similar efficacy compared with ondansetron (OR = 1.49 [95% CI, 0.90-2.43]), tropisetron (OR = 1.69 [95% CI, 0.92-3.13]), and dolasetron (OR = 1.32 [95% CI, 0.71-2.38]). Ondansetron exhibited comparable efficacy compared with tropisetron (OR = 1.14 [95% CI, 0.66-1.96]) and dolasetron (OR = 0.88 [95% CI, 0.51-1.47]). Tropisetron and dolasetron were also similar in efficacy (OR = 0.78 [95% CI, 0.40-1.45]). All 5-HT(3) antagonists were statistically significantly better at preventing PONV or POV than placebo.

CONCLUSIONS

With respect to PONV prophylaxis, granisetron was significantly better than ondansetron and dolasetron; ondansetron, tropisetron, and dolasetron exhibited similar efficacy. With respect to POV prophylaxis, ondansetron, granisetron, tropisetron, and dolasetron seemed to have comparable efficacy.

The network meta-analytic-predictive approach to non-inferiority trials

In non-inferiority clinical trials, a test treatment is compared to an active-control rather than to placebo. Such designs are considered when placebo is unethical or not feasible. The critical question is whether the test treatment would have been superior to placebo, had placebo been used in the non-inferiority trial. This question can only be addressed indirectly, based on information from relevant historical trials with data on active-control and placebo. The network meta-analytic-predictive approach to non-inferiority trials is based on a network meta-analysis of the data from the historical trials and the non-inferiority trial, and the prediction of the putative test vs. placebo effect in the non-inferiority trial. The approach extends previous work by incorporating between-trial variability for all relevant parameters and focusing on the parameters in the non-inferiority trial rather than on population means. Two prominent examples with binary outcomes are used to illustrate the approach.

Issues in performing a network meta-analysis

The example of the analysis of a collection of trials in diabetes consisting of a sparsely connected network of 10 treatments is used to make some points about approaches to analysis. In particular various graphical and tabular presentations, both of the network and of the results are provided and the connection to the literature of incomplete blocks is made. It is clear from this example that is inappropriate to treat the main effect of trial as random and the implications of this for analysis are discussed. It is also argued that the generalisation from a classic random-effect meta-analysis to one applied to a network usually involves strong assumptions about the variance components involved. Despite this, it is concluded that such an analysis can be a useful way of exploring a set of trials.