Review
Evidence-Based and Personalized Medicine. It’s [AND] not [OR]

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Good clinical practice is an amalgamation of personalized medicine with evidence-based medicine in the best interests of patient. Hence, our title uses Boolean operators to indicate that it is [AND] not [OR]. This is the syntax of formal searching for systematic reviews, ensuring that all the evidence is found. Comprehensive evidence-based guidance can thus be formulated. Many residents and fellows around the world, and their chiefs, are now exposed to consensus documents, white papers, levels of appropriateness, and guidelines and are in many jurisdictions expected to comply with them. However, they are the summation of many forms of evidence, each of which has its place, and we consider them in turn in this article.

Section snippets

The Pyramid of Evidence Versus the Best Available Evidence

The EBM movement introduced doctors to the pyramid of evidence which ranked the value of evidence from highest to lowest (Fig 2). In present day surgical practice this ranking may be used in the levels of evidence for clinical practice guidelines [3], but it is a subject of debate and change. Although helpful in categorizing types of studies, it has become clear that it is too simplistic to rank evidence by methodologic sophistication. There are times when accurate observation is most or all

Case Reports

Humans have evolved as a successful species by observation and experimentation with the world around us. Having discovered which berries are nourishing and which are poisonous, how to hunt and kill an animal, how to catch a fish, how to make a controlled fire and to cook with it, man’s instinct is to stick with what he knows works. In medicine we love case reports as can readily be gathered from the tally of published items in The Annals of Thoracic Surgery volume 100 (Fig 3).

A case report is

Case Series

These are observational studies that report on a subject group without a comparison population. In surgery they are typically a single surgeon or an institutional report summarizing a sequence of operations of a particular type. Case series remain one of the most common forms of evidence in journals of clinical surgery (Fig 3). They are low cost and easy to conduct. They may be helpful in refining new techniques or in defining treatment protocols. The limitations are that there was an unknown

Registries

For a recently introduced or evolving treatment there is commonly a call to set up a registry. People offering the treatment are invited to join and pool their data. Sometimes contributing data to the registry is a requirement to have access to a device or equipment. The virtue is that a large number of patients can be included.

Prospective Cohort Studies

A cohort study is one in which a group of subjects, selected to represent the population of interest, is studied over time. A cohort study may be either retrospective or prospective. Retrospective cohort studies concern a certain exposure in the past (eg, an operation) and then study the occurrence of an outcome (eg, death or complications) until the present time. Prospective cohort studies start in present time and include future patients with a certain exposure and then wait for prespecified

Matching Studies

A comparison group is derived from existing data. Patients who did not have the treatment but might have are selected from a data set to match as many factors as are available with patients who did have the treatment. There may be more than one patient matched. They may be matched as a group. A standard method at present is to derive a propensity score based on available predictors of the risk of an adverse outcome. It only works if patients were suitable for both courses of action. If there is

Randomized Controlled Trials

There are several essential features of the typical two-arm randomized trial. Its design can be simplified to the acronym PICO (P for participants, patients, problem, or population; I for the intervention under test; C for the control group or comparator; and O for the outcome(s) to be reported).

The reporting of randomized trials has been standardized in the CONSORT statement (Consolidated Standards of Reporting Trials) which if adhered to greatly assists in reviewing the study and later

Systematic Reviews

Before making guidelines for treatment, or embarking on a new trial to resolve a question with respect to treatment, it is best practice to systematically review all the evidence available. This is clearly preferable to nonsystematic selective citing by guidelines committees; hence, the need to a priori clearly document search terms and strategies as hinted at in the title of this article. By individually assessing studies for their sample size, patient and treatment characteristics, quality,

Clinical Practice Guidelines

Ideally, we want to combine all available evidence when we attempt to provide guidance for optimal patient treatment. Although a systematic review of all relevant RCTs may provide cause–effect relationships, it is often not generalizable to all patients in clinical practice. However, observational studies may be more generalizable, but they only provide associations between patient and treatment characteristics and outcome. They are subject to reporting bias because we tend to prefer to publish

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