Cochrane Reviews have recently started including the quantity I 2 to help readers assess the consistency of the results of studies in meta-analyses. What does this new quantity mean, and why is assessment of heterogeneity so important to clinical practice? 

Systematic reviews and meta-analyses can provide convincing and reliable evidence relevant to many aspects of medicine and health care.1 Their value is especially clear when the results of the studies they include show clinically important effects of similar magnitude. However, the conclusions are less clear when the included studies have differing results. In an attempt to establish whether studies are consistent, reports of meta-analyses commonly present a statistical test of heterogeneity. The test seeks to determine whether there are genuine differences underlying the results of the studies (heterogeneity), or whether the variation in findings is compatible with chance alone (homogeneity). However, the test is susceptible to the number of trials included in the meta-analysis. We have developed a new quantity, I 2, which we believe gives a better measure of the consistency between trials in a meta-analysis.

Assessment of the consistency of effects across studies is an essential part of meta-analysis. Unless we know how consistent the results of studies are, we cannot determine the generalisability of the findings of the meta-analysis. Indeed, several hierarchical systems for grading evidence state that the results of studies must be consistent or homogeneous to obtain the highest grading.2–4

Tests for heterogeneity are commonly used to decide on methods for combining studies and for concluding consistency or inconsistency of findings.5 6 But what does the test achieve in practice, and how should the resulting P values be interpreted?

A test for heterogeneity examines the null hypothesis that all studies are evaluating the same effect. The usual test statistic …

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Measuring inconsistency in meta-analyses

Systematic review and meta-analysis

Systematic reviews and meta-analyses are essential to summarize evidence relating to efficacy and safety of health care interventions accurately and reliably. The clarity and transparency of these reports, however, is not optimal. Poor reporting of systematic reviews diminishes their value to clinicians, policy makers, and other users.

Since the development of the QUOROM (QUality Of Reporting Of Meta-analysis) Statement—a reporting guideline published in 1999—there have been several conceptual, methodological, and practical advances regarding the conduct and reporting of systematic reviews and meta-analyses. Also, reviews of published systematic reviews have found that key information about these studies is often poorly reported. Realizing these issues, an international group that included experienced authors and methodologists developed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) as an evolution of the original QUOROM guideline for systematic reviews and meta-analyses of evaluations of health care interventions.

The PRISMA Statement consists of a 27-item checklist and a four-phase flow diagram. The checklist includes items deemed essential for transparent reporting of a systematic review. In this Explanation and Elaboration document, we explain the meaning and rationale for each checklist item. For each item, we include an example of good reporting and, where possible, references to relevant empirical studies and methodological literature. The PRISMA Statement, this document, and the associated Web site (http://www.prisma-statement.org/) should be helpful resources to improve reporting of systematic reviews and meta-analyses.

/pdf/the-prisma-statement-for-reporting-systematic-reviews-and-3j53e5oe33.pdf

The PRISMA Statement for Reporting Systematic Reviews and Meta-Analyses of Studies That Evaluate Health Care Interventions: Explanation and Elaboration

"The Seventh Report of the Joint National Committee on Prevention, Detection,
Evaluation, and Treatment of High Blood Pressure" provides a new guideline
for hypertension prevention and management. The following are the key messages(1) In persons older than 50 years, systolic blood pressure (BP) of
more than 140 mm Hg is a much more important cardiovascular disease
(CVD) risk factor than diastolic BP; (2) The risk of CVD, beginning at 115/75
mm Hg, doubles with each increment of 20/10 mm Hg; individuals who are normotensive
at 55 years of age have a 90% lifetime risk for developing hypertension; (3)
Individuals with a systolic BP of 120 to 139 mm Hg or a diastolic BP of 80
to 89 mm Hg should be considered as prehypertensive and require health-promoting
lifestyle modifications to prevent CVD; (4) Thiazide-type diuretics should
be used in drug treatment for most patients with uncomplicated hypertension,
either alone or combined with drugs from other classes. Certain high-risk
conditions are compelling indications for the initial use of other antihypertensive
drug classes (angiotensin-converting enzyme inhibitors, angiotensin-receptor
blockers, β-blockers, calcium channel blockers); (5) Most patients with
hypertension will require 2 or more antihypertensive medications to achieve
goal BP (<140/90 mm Hg, or <130/80 mm Hg for patients with diabetes
or chronic kidney disease); (6) If BP is more than 20/10 mm Hg above goal
BP, consideration should be given to initiating therapy with 2 agents, 1 of
which usually should be a thiazide-type diuretic; and (7) The most effective
therapy prescribed by the most careful clinician will control hypertension
only if patients are motivated. Motivation improves when patients have positive
experiences with and trust in the clinician. Empathy builds trust and is a
potent motivator. Finally, in presenting these guidelines, the committee recognizes
that the responsible physician's judgment remains paramount.

https://jamanetwork.com/journals/jama/articlepdf/196589/JSC30096.pdf

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report.

The Cochrane Handbook for Systematic Reviews of Interventions is the official document that describes in detail the process of preparing and maintaining Cochrane systematic reviews on the effects of healthcare interventions.

/pdf/cochrane-handbook-for-systematic-reviews-of-interventions-1xbdy6uvru.pdf

Cochrane Handbook for Systematic Reviews of Interventions

Background: Bleeding during acute coronary syndromes (ACS) is associated with worse prognosis. TRITON - TIMI 38 was designed for all patients to have cardiac catheterization, providing an opportunity to evaluate the effects of arterial access site and management on the rates of hemorrhage. Methods: TRITON - TIMI 38 included 13608 patients with ACS; 99% underwent PCI at the time of randomisation. We compared the incidence of non-CABG TIMI major and minor bleeding between three groups: radial artery access (RAA), and femoral artery access with (FAA-CD) and without the use of an arterial closure device (FAA-NC). Results: FAA was used in 12273 (92%) of patients undergoing angiography. FAA-CD was used in 3842 (31%) of FAA. RAA was used in 1120 patients (8%). Compared to FAA, patients with RAA had less prior CAD (MI, PCI or CABG) less frequently received drug-eluting stents and glycoprotein IIb/IIIa inhibitors (GPI). Femoral closure devices were used more often in patients > 90 kg, with a GPI and less frequently in patients chronic kidney disease or prior atherosclerosis (MI, stroke, PAD). TIMI non-CABG major bleeding was non-significantly less frequent with RAA. RAA was associated with a lower rate of TIMI major or minor non-CABG instrumented bleeding (Table, HR 3.09; P=0.004) and blood transfusion (Table; HR 2.05; P=0.002). The rates of spontaneous bleeding were not affected by the site of the arterial access. (Table). FAA-CD had similar bleeding and transfusion rates to FAA-NC. (Table). The previously reported higher rates of bleeding and transfusion with prasugrel were limited to FAA. Conclusions: In this large group of patients undergoing PCI for ACS, RAA, but not femoral closure devices, were associated with significantly lower rates of instrumented bleeding and transfusion and attenuated the bleeding differences between prasugrel or clopidogrel. A strategy of RAA in the presence of intensive antiplatelet therapy warrants further study to reduce bleeding complications.

Abstract 985: The Influence of the Arterial Access Site and its Management on Bleeding Events in Acute Coronary Syndromes in TRITON - TIMI 38

The ideal approach to the management of cardiac rhythm disorders depends on the following: 

1.

Proper identification of the arrhythmia.




2.

An understanding of the natural history of the arrhythmia in a particular patient.




3.

An understanding of the multiple factors that may precipitate and maintain a cardiac rhythm disturbance in a particular patient.




4.

An understanding of the pharmacology of the numerous antiarrhythmic drugs available.




5

An appropriate clinical assessment of the risk to the patient due to the cardiac arrhythmia versus the side effects that might ensue upon initiation of treatment with an antiarrhythmic drug.

Pharmacological Therapy of Cardiac Arrhythmias: Antiarrhythmic Agents, Beta Adrenoceptor Blocking Agents, and Digitalis Glycosides

Long-term follow-up in patients with medically refractory atrial fibrillation treated with propafenone and sotalol

Acute myocardial infarction is often accompanied by some degree of heart failure. In general, anterior infarction is associated with more severe pulmonary congestion than is inferior infarction. Inferoposterior infarction is occasionally associated with the syndrome of right ventricular infarction, i.e., hypotension with or without bradycardia, clear lung fields, and elevated right heart filling pressures. It is common for patients to have no symptoms of heart failure when an S4 gallop rhythm is present (usually reflecting elevated left ventricular end-diastolic pressure) , and about half the patients with significant pulmonary congestion evident on chest x-ray have no abnormal physical findings.

Elliott M. Antman

Papers

Abstract 985: The Influence of the Arterial Access Site and its Management on Bleeding Events in Acute Coronary Syndromes in TRITON - TIMI 38

Pharmacological Therapy of Cardiac Arrhythmias: Antiarrhythmic Agents, Beta Adrenoceptor Blocking Agents, and Digitalis Glycosides

Long-term follow-up in patients with medically refractory atrial fibrillation treated with propafenone and sotalol

Complications of Acute Myocardial Infarction

Increased risk of adverse outcomes with proximal culprit artery lesions in acute myocardial infarction