Evidence-Based Practice Parameters: The Approach of the American Society of Anesthesiologists

INTRODUCTION

Practice parameters are “strategies for patient management developed by the profession to assist physicians in clinical decision making.” The evidence-based practice parameters of the American Society of Anesthesiologists (ASA) include practice guidelines and practice advisories. Although both types of guidance employ similar approaches and methodologies, the evidence base supporting recommendations in practice advisories is limited in quantity, quality, and consistency. This chapter focuses on practice guidelines because they are the most evidence based, but the principles discussed apply equally to practice advisories.

The contemporary era in ASA practice parameter development began in 1993 with the publication of the difficult airway and pulmonary artery catheterization guidelines. In total, 14 practice guidelines and 8 practice advisories have been published along with numerous updates. In 2020, the number of citations to the guidelines indexed in the Web of Science approached 10,000.

CLINICAL PRACTICE GUIDELINES STANDARDS

Although practice guidelines date to as early as 1938, it was not until 2011 that the National Academy of Medicine ^a

a Still known as the Institute of Medicine in 2011.

released standards for developing trustworthy clinical practice guidelines. Congress initiated the development of standards to improve the quality of guidelines. A companion set of standards was released simultaneously for systematic reviews—a requirement for a trustworthy practice guideline.

The clinical practice guideline standards address eight areas: (1) transparency, (2) conflicts of interest, (3) development group composition, (4) systematic review conduct, (5) ratings for the strength of recommendations, (6) the articulation of recommendations, (7) external reviews, and (8) updates. Although all of the standards apply to guideline development, our focus is on the evidentiary foundations, which involves the synthesis of evidence informing recommendations (standards included in areas 4 through 6).

SYSTEMATIC REVIEWS AND GUIDELINES

The synthesis of evidence provided by a systematic review is the foundation of evidence based guideline recommendations. Although systematic reviews can be complex undertakings, their conduct should be transparent, unbiased, reproducible, and devised to produce a valid synthesis of evidence. Guideline users should understand the approach adopted and the basis for decisions concerning the systematic review’s conduct. The goals of an evidence synthesis are not simply to offer conclusions on whether interventions may, or may not, be more effective than the relevant comparator(s). The evidence synthesis must also quantify uncertainty in comparative effects to allow for the incorporation of patient preferences and values in recommendations. In this way, guideline recommendations can best inform decision making, improve patient care, and help create better health outcomes.

CLINICAL QUESTIONS AND PICOTS (POPULATION, INTERVENTIONS, COMPARATORS, OUTCOMES, TIMING, AND SETTING)

The first steps in a guideline’s systematic review are defining the PICOTS (population, interventions, comparators, outcomes, timing, and setting) and framing the questions to address. Well-formulated questions facilitate and guide the review process—from searching and study selection together with the approach to evidence synthesis. The PICOTS and questions add transparency, reflecting the goals and thought processes of guideline developers.

Systematic review questions can address therapies, diagnoses, prognoses, the predictions of treatment response, and screenings. The different types of questions are generally answered by different study designs and approaches to evidence synthesis. For example, randomized designs are typically sought for therapeutic interventions, whereas observational studies most often form the evidence base for addressing diagnostic and prognostic questions.

Table 1.1 illustrates the PICOTS derived from the 2020 central venous access guidelines, which correspond to the therapeutic question: What is the effectiveness of antiseptic-treated catheters for reducing the incidence of catheter-related bloodstream infection and associated morbidity and mortality?