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Clinical

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Clinical guidelines: Grading the evidence behindthe practiceKathleen Rich, PhD, RN, CCNS

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Clinical practice guidelines are statements to assist in healthcare decisions for patients with the same illness or pro-

cedure. Guidelines comprise elements that describe different aspects of the patient’s condition and the required care.

Many organizations publish guidelines, including the Society for Vascular Nursing. Evidence is the foundation of guide-

lines and their practice recommendations. This evidence is primarily from research. Developing a grading system for the

research and the associated practice elements improves the strength of a guideline’s statements. This article discusses the

grading system selected by the Society for Vascular Nursing (SVN) Practice and Research Committee when creating the

forthcoming carotid stent nursing practice guideline. (J Vasc Nurs 2012;30:132-133)

Clinical practice guidelines are defined as systematicallydeveloped statements to assist practitioners in making healthcaredecisions and management options for large groups of patientswith the same illness or procedure.1 The guidelines may be con-sidered reports that describe the role of treatment modalities andcare to be given for a specific disease entity. Guidelines are de-veloped by individuals and organizations with expertise in thatparticular disease process or procedure. Early published guide-line literature relied heavily on reference books and expert opin-ions in making the care recommendations. This reliance resultedin the potential for conflict of interest, individual practice varia-tions and questions regarding the source of the practice dictate. Itbecame evident that the approach had to be modified. Althoughtextbooks and opinions remain a component, guideline state-ments needed to be evidence-based and built on research find-ings. Developing a guideline founded on available researchreduces bias, decreases practice errors, improves communicationand diminishes the potential for conflict of interest by both guide-line developers and reviewers.2 Utilizing a scoring or gradingsystem for the research and associated practice componentsallows for a direct identification regarding the science on whichthe recommendations are based. Specifying the rationale fordeveloping a guideline, delineating the pathophysiology behindthe selected disease entity, assembling the appropriate literatureand ranking the evidence all promote guideline transparency.

e IU Health La Porte Hospital, La Porte, Indiana.

onding author: Kathleen Rich, PhD, RN, CCNS, Cardio-r Clinical Specialist IU Health La Porte Hospital, 1007way, La Porte, IN 46350 (E-mail: krich@iuhealth.org).

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ht � 2012 by the Society for Vascular Nursing, Inc.

.doi.org/10.1016/j.jvn.2012.09.001

Transparency indicates that an individual is able to clearly iden-tify the background, processes and research behind the prac-tice.3,4 This transparency lends strength, scientific rigor andbelievability to the practice recommendations. The Society forVascular Nursing (SVN) Practice and Research Committeerecognized this when developing the forthcoming carotid stentclinical practice guideline for nurses. The purpose of thisarticle is to discuss the grading system selected for thesupporting evidence used in this guideline.

EVIDENCE GRADING SYSTEM

Research studies have different strengths and values thatclinicians should identify when making a clinical decision. Thegoal is to simplify the intricate assortment of evidence throughuse of a ranking approach. There are multiple different ways toclassify or grade the evidence. This classification objectivelydescribes the existence and types of research supporting the orga-nization’s practice statements.5 Organizations will specify anddefine the method behind the level of evidence classificationand practice recommendations used in their guidelines. Evidenceis ranked alphabetically or numerically (or a combination) fromhighest to lowest levels based on the number and type of avail-able research studies.6 This hierarchical approach in classifyingthe evidence is widely accepted.7

Because no single standardized hierarchy or grading systemexists, many organizations have either designed their ownevidence-grading criteria or utilized or modified a previously re-ported option. Several organizations, such as the American HeartAssociation, use two classification systems, one for practice rec-ommendations (Class Ia, IIa, IIb, III) and a second for the levelsof evidence (A, B, C) that summarize the research behind the prac-tice.8 Others, such as the American Association of Critical CareNurses, use a single alphabetical system to summarize the evi-dence levels.9 The SVN Practice and Research Committee

Classification Definition

I Randomized control trial without significant limitations, systematic review or meta -analysis

II Randomized control trial with important limitations (e.g., methodological flaws or inconsistent results), observational studies (e.g., cohort or case-control)

III Qualitative studies, case study, or series

IV Evidence from reports of expert committees and/or expert opinion of the guideline panel, standards of care and clinical protocols, animal studies

Figure 1. SVN Guideline Evidence Classification System.

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reviewed evidence-leveling systems published by several medicaland nursing societies. The selected concept started with a general-ized grading system reported in Melnyk and Fineout-Overholt6

that was modified by the American Association of NeuroscienceNurses (ANNA).10 The SVN Practice and Research Committeeadapted that data classification system component when develop-ing the carotid stent nursing practice recommendations.

The final grading system includes four classes of evidence be-hind the practice statements. Class I is considered the highestlevel of evidence and includes meta-analyses, systematic reviewsand randomized control trials without significant limitations.A meta-analysis is a process that combines multiple similar studyresults into a single summary finding to assess the effect of anintervention.7 A systematic review involves the researcher askinga specific clinical question, following a strict protocol tominimize bias, and reviewing and appraising the availableevidence to make practice recommendations.11 The studies ina systematic review are different and cannot be combined as ina meta-analysis. A randomized control trial is a study in whichparticipants are randomly (by chance) assigned the experimentaltreatment or intervention and another group (control group) is as-signed either another treatment or placebo.7

Class II evidence includes randomized control trials withimportant limitations (e.g., methodological flaws or inconsistentresults) and observational studies (e.g., cohort or case control).Study limitations are those factors or restrictions in a study thatlimit the generalization of the findings or affect the reliability.12

A cohort study is a type of observational research in which a de-fined group of persons (known as the cohort) are followed overa specified period of time to determine whether they will developa disease or health event.7 A cohort study may be either prospec-tive (measuring events that are occurring in real time) or retro-spective (examining events, conditions, and so forth that haveoccurred in the past).

Class III includes qualitative studies, case study, or series.Qualitative research also employs a systematic approach; however,data are collected through personal interviews to analyze a life ex-perience or a specific situation to give it meaning.13 Class IV in-volves evidence from reports of expert committees and/or expertopinion of a guideline panel, standards of care and clinical proto-cols or animal studies. Figure 1 summarizes the evidence gradingsystem employed by the SVN Practice and Research Committee.

SUMMARY

Utilizing the above-described evidence classification rank-ing, SVN has joined other professional nursing and medical

organizations in having a template behind their practice recom-mendations. The SVN Practice and Research committee mem-bers critically appraised the meta-analyses, clinical trials andother literature supporting the carotid stent nursing practiceguideline for ranking and inclusion in that document. This sys-tematic approach to grading the evidence behind the practicefulfills the carotid stent guideline’s purpose: to specify theevidence-based nursing care to be delivered to this patientpopulation.

REFERENCES

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2. GRADE Working Group. Grading quality of evidence andstrength of recommendations. Br Med J 2004;328:1-8.

3. American Academy of Pediatrics Steering Committee onQuality Improvement and Management. Toward transparentclinical policies. Pediatrics 2008;121(3):643-6.

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6. Melnyk B., Fineout-Overholt, E. Making the case forevidence-based practice and cultivating a spirit of inquiry.In: Evidence-based nursing practice in nursing and health-care: a guide to best practice. 2nd Ed. Melnyk, B., Fineout-Overholt, E. (Eds). 2011. Philadelphia: Wolters KluwerHealth/Lippincott, Williams & Wilkins. p. 12.

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9. Armola R, Bourgault A, Halm M, et al. AACN levels ofevidence: what’s new? Crit Care Nurs 2009;29(4):70-3.

10. American Association of Neuroscience Nurses ClinicalPractice Guideline Series. Care of the patient with aneurysmalsubarachnoid hemorrhage. Revised 2009. Available at: http://www.aann.org/pubs/content/guidelines.html.AccessedAugust12, 2012.

11. Burns N, Grove S. Understanding nursing research. 5th Ed.Maryland Heights, MO: Elsevier; 2011; p. 469.

12. Burns N, Grove S. Understanding nursing research. 5th Ed.Maryland Heights, MO: Elsevier; 2011; p. 48.

13. Powers, B. Generating evidence through qualitative research.In: Melnyk B. Fineout-Overholt, Evidence-based nursingpractice in nursing and healthcare: a guide to best practice.2nd Ed. Melnyk, B., Fineout-Overholt, E. (Eds). 2011.Philadelphia: Wolters Kluwer Health/Lippincott, Williams& Wilkins. p. 435.