Network Meta-Analyses: The “White Whale” for Cardiovascular Specialists

Systematic Reviews and Meta-Analyses in Cardiac Surgery: Rules of the Road - Part 2

In the era of evidence-based medicine, systematic reviews and meta-analyses are considered at the top of evidence hierarchy. Despite the almost exponential increase in the number of published meta-analyses over the course of the last decades, only a small minority of them are of high quality, with major flaws involving every aspect of the meta-analytic process. The strength of a meta-analysis is closely linked to the quality of the included studies. Once preliminary phases are completed, it is vital that selected papers undergo a thorough quality assessment, using the most appropriate tools among those available. Analytical approaches must be tailored to the nature of the extracted data and the specific purpose of the meta-analysis. Appraisal of heterogeneity is a key step to inform subgroup or meta-regression analyses. The solidity of the results of the main analysis (especially in meta-analyses of observational studies or studies with high heterogeneity) should be tested by means of pertinent sensitivity analyses. Finally, the investigators should be aware of the possibility of publication bias and make efforts to assess it using qualitative and quantitative methods. The aim of the second part of this expert review is to provide guidance on how to appropriately perform trial level meta-analyses, with particular focus on the quality assessment of the included studies, the choice of the appropriate statistical approach, the methods to deal with heterogeneity (including subgroup, meta-regression, and sensitivity analyses), and the appraisal of publication bias.

Optical coherence tomography evaluation of intermediate-term healing of different stent types: systemic review and meta-analysis

AIMS

The intermediate-term incidence of strut malapposition (SM) and uncovered struts (US), and the degree of neointimal thickness (NIT) according to stent type have not been characterized.

METHODS AND RESULTS

All studies of >50 patients in which optical coherence tomography was performed between 6 and 12 months after stent implantation were included. The incidences of SM and US were the co-primary end points, while NIT was the secondary end point. A total of 458 citations were initially appraised at the abstract level, and 11 full-text studies (280 652 analysed struts, 921 patients) were assessed. The 6-12 months incidences of SM and US were 5.0 and 7.8%, respectively, and the mean NIT was 206 μm. Biolimus-eluting stents (BES) and bioresorbable vascular scaffolds (BVS) had the highest SM rates (2.7 and 3.8%, respectively), while everolimus-eluting stents (EES) and fast-release zotarolimus-eluting stents (ZES) had the lowest SM rates (0.9 and 0.1%, respectively). BES and sirolimus-eluting stents (SES) had the highest US rates (7.7 and 8.8%, respectively), while bare metal stents (BMS) and ZES had the lowest US rates (0.3 and 0.3%, respectively). BMS had the greatest NIT (340 μm), while SES, EES, and BES had the least NIT.

CONCLUSION

Second-generation drug-eluting stents (DES) have better intermediate-term strut apposition and coverage than first-generation DES, BVS, and BMS. EES demonstrate the overall best combination of healing with suppression of neointimal hyperplasia at 6-12 months. Further studies with clinical correlation are warranted to determine the implications of these findings.

Meta-Analysis of the Duration of Dual Antiplatelet Therapy in Patients Treated With Second-Generation Drug-Eluting Stents

The purpose of the study was to evaluate the optimal duration of dual antiplatelet therapy (DAPT) after percutaneous coronary intervention, especially in the era of second-generation drug-eluting stents (DES). The work was conducted from November 2014 to April 2015. All randomized controlled trials comparing short (<12 months) versus long (≥12 months) DAPT in patients treated with second-generation DES were analyzed. Sensitivity analyses were performed for length of DAPT and type of DES. All-cause death was the primary end point, whereas cardiovascular death, myocardial infarction (MI), stent thrombosis (ST), and major bleeding were secondary end points. Results were pooled and compared with random-effect models and meta-regression analysis. Eight randomized controlled trials with 18,810 randomized patients were included. The studies compared 3 versus 12 months of DAPT (2 trials), 6 versus 12 months (3 trials), 6 versus 24 months (1 trial), 12 versus 24 months (1 trial), and 12 versus 30 months (1 trial). Comparing short versus long DAPT, there were no significant differences in all-cause death (odds ratio [OR] 0.87; 95% confidence interval [CI] 0.66 to 1.44), cardiovascular death (OR 0.95; 95% CI 0.65 to 1.37), and ST (OR 1.20; 95% CI 0.79 to 1.83), and no differences were present when considering everolimus-eluting and fast-release zotarolimus-eluting stents separately. Shorter DAPT was inferior to longer DAPT in preventing MI (OR 1.35; 95% CI 1.03 to 1.77). Conversely, major bleeding was reduced by shorter DAPT (OR 0.60; 95% CI 0.42 to 0.96). Baseline features did not influence these results in meta-regression analysis. In conclusion, DAPT for ≤6 months is reasonable for patients treated with everolimus-eluting and fast-release zotarolimus-eluting stents, with the benefit of less major bleeding at the cost of increased MI, with similar survival and ST rates. An individualized patient approach to DAPT duration should take into account the competing risks of bleeding and ischemic complications after present-generation DES.

Comparative safety and efficacy of statins for primary prevention in human immunodeficiency virus-positive patients: a systematic review and meta-analysis

The efficacy and safety of different statins for human immunodeficiency virus (HIV)-positive patients in the primary prevention setting remain to be established. In the present meta-analysis, 18 studies with 736 HIV-positive patients receiving combination antiretroviral therapy (cART) and treated with statins in the primary prevention setting were included (21.0% women, median age 44.1 years old). The primary endpoint was the effect of statin therapy on total cholesterol (TC) levels. Rosuvastatin 10 mg and atorvastatin 10 mg provided the largest reduction in TC levels [mean -1.67, 95% confidence interval (CI) (-1.99, -1.35) mmol/L; and mean -1.44, 95% CI (-1.85, -1.02) mmol/L, respectively]. Atorvastatin 80 mg and simvastatin 20 mg provided the largest reduction in low-density lipoprotein (LDL) [mean -2.10, 95% CI (-3.39, -0.81) mmol/L; and mean -1.57, 95% CI (-2.67, -0.47) mmol/L, respectively]. Pravastatin 10-20 mg [mean 0.24, 95% CI (0.10, 0.38) mmol/L] and atorvastatin 10 mg [mean 0.15, 95% CI (0.007, 0.23) mmol/L] had the largest increase in high-density lipoprotein, whereas atorvastatin 80 mg [mean -0.60, 95% CI (-1.09, -0.11) mmol/L] and simvastatin 20 mg [mean -0.61, 95% CI (-1.14, -0.08) mmol/L] had the largest reduction in triglycerides. The mean discontinuation rate was 0.12 per 100 person-years [95% CI (0.05, 0.20)], and was higher with atorvastatin 10 mg [26.5 per 100 person-years, 95% CI (-13.4, 64.7)]. Meta-regression revealed that nucleoside reverse transcriptase inhibitors-sparing regimens were associated with reduced efficacy for statin's ability to lower TC. Statin therapy significantly lowers plasma TC and LDL levels in HIV-positive patients and is associated with low rates of adverse events. Statins are effective and safe when dose-adjusted for drug-drug interactions with cART.

GetReal in network meta-analysis: a review of the methodology

Pairwise meta-analysis is an established statistical tool for synthesizing evidence from multiple trials, but it is informative only about the relative efficacy of two specific interventions. The usefulness of pairwise meta-analysis is thus limited in real-life medical practice, where many competing interventions may be available for a certain condition and studies informing some of the pairwise comparisons may be lacking. This commonly encountered scenario has led to the development of network meta-analysis (NMA). In the last decade, several applications, methodological developments, and empirical studies in NMA have been published, and the area is thriving as its relevance to public health is increasingly recognized. This article presents a review of the relevant literature on NMA methodology aiming to pinpoint the developments that have appeared in the field. Copyright © 2016 John Wiley & Sons, Ltd.

Efficacy and Safety of Available Protocols for Aspirin Hypersensitivity for Patients Undergoing Percutaneous Coronary Intervention: A Survey and Systematic Review

BACKGROUND

The most suitable approach for patients with aspirin hypersensitivity undergoing percutaneous coronary intervention remains to be assessed.

METHODS AND RESULTS

Pubmed, Google Scholar, and Cochrane were systematically searched for papers describing protocols about aspirin hypersensitivity in the percutaneous coronary intervention setting. Discharge from hospital with aspirin was the primary end point, whereas rates of adverse reactions being a secondary outcome. An online international survey was performed to critically analyze rates of aspirin hypersensitivity and its medical and interventional management. Eleven studies with 283 patients were included. An endovenous desensitization protocol was performed on one of them, with high efficacy rate (98%) and a low adverse reaction rate when compared with oral administration. No significant differences were reported among the oral protocols in terms of efficacy (less versus more fractionated [95.8% {95.4%-96.2%} versus 95.9% {95.2-96.5%}]), whereas higher incidence of rash and angioedema were reported for protocols with <6 doses escalation (2.6% [1.1%-4.1%] versus 2.6% [1.9%-3.2%]). In the survey, we collected answer from 86 physician of the 100 interviewed. Fifty-six percent of them managed aspirin hypersensitivity changing the therapeutic regimen (eg, clopidogrel monotherapy and indobufen). Despite the previous safety data, desensitization protocols were adopted by only 42% of surveyed cardiologist.

CONCLUSIONS

Available protocols for aspirin hypersensitivity are effective and safe, representing a feasible approach for patients needing dual antiplatelet therapy.

A 'reluctant' critical review: 'Manual for evidence-based clinical practice (2015)'

BACKGROUND

The Users' Guides to the Medical Literature Manual has been a major influence on the teaching and practice of health care globally.

METHODS

The 3rd edition of the multi-authored Manual was reviewed using the principles outlined in Evidence-based Medicine (EBM) texts. One 'clinical scenario' was selected for critical appraisal, as were several chapters; objectivity was enhanced by citing references to support opinions. RESULTS (SUMMARY OF THE APPRAISAL): (1) Strengths: Clinical pearls, too numerous to list.

EXAMPLES

(i) evidence is never enough to drive clinical decision making; (ii) do not rush to adopt new interventions; and (iii) question efficacy data based only on surrogate markers. (2) Weaknesses: The Manual shares shortcomings of textbooks discussed by Straus et al.: (i) references may not be current, important ones may be excluded and citations may be selective; (ii) often, opinion-based; and (iii) delays between revisions. (3) Notable omissions: Little or no discussion of: (i) important segments of the population: those <18 years of age, >65 years of age and those with multimorbidity; (ii) surgical disciplines; (iii) Greenhalgh et al.'s essay on EBM; (iv) alternate views on the hierarchy of evidence; and (vi) critical thinking. (4) Additional issues: (i) Omission of important references on dabigatran (clinical scenario: chapter 13.1); (ii) authors' advice (Chapter 13.3) to 'bypass the discussion section of published research'; and (iii) the advocacy of pre-appraised sources of evidence and network meta-analysis without warnings about limitations, are critiqued.

CONCLUSION

The Manual has several clinical pearls but readers should also be aware of shortcomings.

Clinical Outcomes of Revascularization Strategies for Patients With MVD/LMCA Disease: A Systematic Review and Network Meta-Analysis

Hybrid coronary revascularization (HCR), a new minimally invasive procedure for patients requiring revascularization for multivessel coronary lesions, combines coronary artery bypass grafting (CABG) for left anterior descending (LAD) lesions and percutaneous coronary intervention (PCI) for non-LAD coronary lesions. However, available data related to outcomes comparing the 3 revascularization therapies is limited to small studies.We conducted a search in MEDLINE, EMBASE, and the Cochrane Library of Controlled Trials up to December 31, 2014, without language restriction. A total of 16 randomized trials (n=4858 patients) comparing HCR versus PCI or off-pump CABG (OPCAB) were included in this meta-analysis. The primary outcomes were major adverse cardiac and cerebrovascular events (MACCE), all-cause death, myocardial infarction (MI), cerebrovascular events (CVE), and target vessel revascularization (TVR). Odds ratios (OR) and 95% confidence intervals (CI) were calculated using random-effect and fixed-effect models. Ranking probabilities were used to calculate a summary numerical value: the surface under the cumulative ranking (SUCRA) curve.No significant differences were seen between the HCR and PCI in short term (in hospital and 30 days) with regard to MACCE (odds ratio [OR] = 0.51, 95% confidence interval [CI] 0.00-2.35), all-cause death (OR = 2.09, 95% CI 0.34-7.66), MI (OR = 1.02, 95% CI 0.19-2.95), CVE (OR = 4.45, 95% CI 0.39-19.16), and TVR (OR = 6.99, 95% CI 0.17-39.39). However, OPCAB had lower MACCE than HCR (OR = 0.19, 95% CI 0.00-0.95). In midterm (1 year and 3 year), in comparison with HCR, PCI had higher all-cause death (OR = 5.66, 95% CI 0.00-13.88) and CVE (OR = 4.40, 95% CI 0.01-5.68), and lower MI (OR = 0.51, 95% CI 0.00-2.86), TVR (OR = 0.53, 95% CI 0.05-2.26), and thus the MACCE (OR = 0.51, 95% CI 0.00-2.35). Off-pump CABG presented a better outcome than HCR with significant lower MACCE (OR = 0.17, 95% CI 0.01-0.68). Surface under the cumulative ranking probabilities showed that HCR may be the superior strategy for MVD and LMCA disease when regarded to MACCE (SUCRA = 0.84), MI (SUCRA = 0.76) in short term, and regarded to MACCE (SUCRA = 0.99), MI (SUCRA = 0.94), and CVE (SUCRA = 0.92) in midterm.Hybrid coronary revascularization seemed to be a feasible and acceptable option for treatment of LMCA disease and MVD. More powerful evidences are required to precisely evaluate risks and benefits of the 3 therapies for patients who have different clinical characteristics.

Meta-analysis of the usefulness of Mitraclip in patients with functional mitral regurgitation

Midterm outcomes for patients presenting with heart failure and functional mitral regurgitation (MR) treated with Mitraclip remain unclear. Pubmed, Medline, and Google Scholar were systematically searched for studies enrolling patients with severe-moderate MR who underwent Mitraclip implantation. All events after at least 6 months were the primary safety end point (including death, rehospitalization for heart failure, and reinterventions), whereas change in the ejection fraction, left ventricular volumes, arterial pulmonary pressure, and left atrial diameters were considered as secondary end points. Meta-regression analysis was performed to evaluate the effect of baseline clinical and echocardiographic parameters on efficacy outcomes: 875 patients were included in 9 studies; 1.48 clips (1.3 to 1.7) for patients were implanted, and after a median follow-up of 9 months (6 to 12), 409 patients (78% [75% to 83%]) were in class New York Heart Association I/II and 57 (11% [8% to 14%]) still had moderate-to-severe MR. Overall adverse events occurred in 137 (26% [20% to 31%]) of the patients and 78 (15% [1% to 17%]) of them died; 6-minute walk test improved by 100 m (83 to 111), whereas a significant reduction in left ventricular volumes and systolic pulmonary pressure was reported. At meta-regression analysis, an increase in left ventricle systolic volumes positively affected reduction of volumes after Mitraclip, whereas atrial fibrillation reduced the positive effect of the valve implantation on ejection fraction on end-diastolic and -systolic volumes. In conclusion, Mitraclip represents an efficacious strategy for patients with heart failure and severe MR. It offers a significant improvement in functional class and in cardiac remodeling, in patients with severely dilated hearts as well, although its efficacy remains limited in the presence of atrial fibrillation.

Meta-analysis of comparison between self-expandable and balloon-expandable valves for patients having transcatheter aortic valve implantation

Two different devices, 1 self-expanding and 1 balloon-expandable, have been developed for patients who underwent transcatheter aortic valve implantation with contrasting data about efficacy and safety. Pubmed, Medline, and Google Scholar were systematically searched for studies of these different devices, with data derived from randomized controlled trial or registries with multivariate analysis. All-cause death at 30 days and at follow-up were the primary end points, whereas postprocedural moderate or severe aortic regurgitation (AR), stroke, major vascular complications, bleedings, and pacemaker implantation the secondary ones. Six studies with 957 self-expanding and 947 balloon-expandable valves were included: 1 randomized controlled trial and 5 observational studies. At 30 days follow-up, rates of death did not differ between self-expanding and balloon-expandable valves (odds ratio [OR] 0.74, 95% confidence interval [CI] 0.47 to 1.17), whereas balloon expandable reduced rates of moderate or severe AR (OR 0.51, 95% CI 0.27 to 0.99) and of pacemaker implantation (OR 0.28, 95% CI 0.17 to 0.47). After a follow-up of 360 days (300 to 390), rates of all-cause death did not differ between the 2 groups. In conclusion, risks of moderate or severe AR and pacemaker implantation were lower with the balloon-expandable devices without an impact on 30 days and midterm mortality.

A network meta-analysis on randomized trials focusing on the preventive effect of statins on contrast-induced nephropathy

Contrast-induced nephropathy is a common complication of iodinated contrast administration. Statins may reduce the risk of contrast-induced nephropathy, but data remain inconclusive. We summarized the evidence based on statins for the prevention of contrast-induced nephropathy with a network meta-analysis. Randomized trials focusing on statins were searched and pooled with random-effect odds ratios. A total of 14 trials (6,160 patients) were included, focusing on atorvastatin (high/low dose), rosuvastatin (high dose), simvastatin (high/low dose), and placebo or no statin therapy before contrast administration. The risk of contrast-induced nephropathy was reduced by atorvastatin high dose and rosuvastatin high dose, with no difference between these two agents. Results for atorvastatin low dose and simvastatin (high/low dose) in comparison to placebo were inconclusive. Atorvastatin and rosuvastatin administered at high doses and before iodinated contrast administration have a consistent and beneficial preventive effect on contrast-induced nephropathy and may actually halve its incidence.