CLINICAL SCENARIO Should Patients Undergoing Noncardiac Surgery Receive β-Blockers?
You receive a request for consultation from a general surgeon regarding the perioperative management of a 66-year-old man undergoing hip replacement surgery in 2 days. The patient has a history of type 2 diabetes and hypertension and is a smoker. He has no history of heart disease. The patient's blood pressure is 135/80 mm Hg. Because the patient has multiple risk factors for heart disease, you are considering whether he should be treated perioperatively with β-blockers to reduce the risk of death, nonfatal myocardial infarction, and other vascular complications.
Being aware that a large amount of literature exists on this controversial topic, you decide to conduct a search that will provide you with an accurate and rapid overview of current best evidence. Because the question is about therapy, you are particularly interested in finding a recent systematic review and meta-analysis of randomized clinical trials (RCTs) that deal with this topic. Using the free federated search engine ACCESSSS (http://plus.mcmaster.ca/accessss; see Chapter 5, Finding Current Best Evidence), you enter these search terms: beta blockers, perioperative, and mortality.
Starting with the summaries at the top of your search output, you locate 2 relevant preappraised summaries on the “management of cardiac risk for noncardiac surgery.” Both summaries cite the results of a large systematic review and meta-analysis published in 2008,1 along with references to current US and European clinical practice guidelines. However, you notice that the last updates of these chapters date back 4 to 6 months ago. You therefore look further down in your search output to check preappraised research (see Chapter 5, Finding Current Best Evidence) and rapidly identify a more recently published systematic review and meta-analysis addressing your question and that was highly rated for relevance and newsworthiness by clinicians from 4 specialties.2 You download the full text of the article reporting this meta-analysis.
Systematic Reviews and Meta-Analysis: An Introduction
A systematic review is a summary of research that addresses a focused clinical question in a systematic, reproducible manner. Systematic reviews can provide estimates of therapeutic efficacy, prognosis, and diagnostic test accuracy and can summarize the evidence for questions of “how” and “why” addressed by qualitative research studies. Although we will refer to other sorts of questions, this chapter focuses on systematic reviews that address the effect of therapeutic interventions or harmful exposures on patient-important outcomes.
A systematic review is often accompanied by a meta-analysis (a statistical pooling or aggregation of results from different studies) to provide a single best estimate of effect. The pooling of studies increases precision (ie, narrows the confidence intervals [CIs]), and the single best effect estimate generated facilitates clinical decision making. Therefore, you may see a published systematic review in which the authors ...