Finding the evidence

CHAPTER 3 Finding the evidence



Nancy Wilczynski, Ann McKibbon



LEARNING OBJECTIVES


After reading this chapter, you should be able to:


• Describe the basics of searching

• Understand how literature services are organised

• Be aware of the major online evidence-based resources and how they fit into the organisation of literature services

• Be aware of the discipline-specific online evidence-based resources

• Know which databases will likely have an answer when searching for evidence for each type of question (that is, intervention, diagnosis, prognosis and qualitative)

• Know how to search for evidence for each type of question

One of the most important and challenging aspects of implementing evidence-based practice can be finding the current best evidence relevant to your clinical question. The internet provides ready and free access to information but the information explosion and the ever-increasing availability of online resources makes finding the current best evidence difficult. Many online resources falsely claim to be ‘evidence-based’, making it difficult for health professionals to navigate internet sites. In addition to discerning if the information provided on the internet site is based on sound evidence, research shows that some of the obstacles that are most frequently encountered when attempting to find the answer to a clinical question are:


• the excessive amount of time required to find information

• difficulty in selecting an optimal strategy to search for information

• failure of the selected resource to provide an answer.1

These barriers can be reduced by approaching the search for the current best evidence in a systematic way that harnesses the organisation of the literature to your advantage. In this chapter, we will show you some of the main ways that you can do this. We will begin by describing the basics of searching, followed by a description of a model that outlines a categorisation of evidence-based information services and how this evidence is processed and presented. Within each category of this model, we will describe the types of evidence that are included and the resources that are available to find that type of evidence. We will concentrate on the resources which have the strongest evidence base as these resources are the ones that are likely to be of most use to you in your clinical practice and are also typically the resources that are easier and faster to use. The chapter concludes with a number of clinical questions and examples of how you can find an answer to these questions using the model and the information resources that are described in the chapter.



The basics of searching


So that your search for evidence is as efficient as possible, it is a good idea to understand some of the basic principles of effective searching, which are:


1. Carefully define your clinical question.

2. Choose your key search terms.

3. Broaden your search if necessary, with synonyms, truncation and/or wildcards.

4. Use Boolean operators.


Carefully define your clinical question


Information about how to construct a well-formulated clinical question, using the PICO format, was provided in Chapter 2.



Choose your key search terms


Using the PICO format to structure your clinical question makes choosing key search terms relatively easy. Typically you would start your search using the ‘P’ (patients [or population]) and ‘I’ (intervention) terms or phrases from your question. For example, if your question was ‘In people with chronic low back pain, is an operant-behavioural graded activity program more effective than physical training in improving functional ability?’ you would start your search with the phrases “chronic low back pain” (‘P’ terms) and “operant-behavioural graded activity” (‘I’ terms).



Broaden your search if necessary


Once you have identified key terms or phrases you should consider broadening your search, particularly if your initial search yields no relevant articles.


• The first way to broaden your search is to consider using synonyms and related terms. For example, if you are searching for articles on clients with “rheumatoid arthritis” you can broaden your search by also searching with the terms “RA” and “rheumatologic disease”. Several online resources list synonyms and related terms for many diseases and conditions, for example, eMedicine from WebMD (http://www.emedicine.com/; choose a condition), eMedicineHealth from WebMD (http://www.emedicinehealth.com/script/main/hp.asp) and Genetics Home Reference from the U.S. National Library of Medicine (http://ghr.nlm.nih.gov/glossary).

• Another way to widen your search is to use truncation and wildcards. When using truncation in a search you enter the first part of a keyword, insert a symbol (usually an asterisk symbol∗) and accept any variant spellings or word endings, from the occurrence of the symbol onward. For example, “disease∗” would retrieve records with the word disease, as well as the words diseases, diseased etc. When using wildcards in a search you enter a wild card character (usually “?”) within or at the end of a keyword to substitute for only one character. Wildcards are particularly useful when searching for some plural forms, such as “wom?n”, which would retrieve records with the words woman and women. Wildcards are also very useful when searching for terms where there is a variation between the American and Australian spelling of the words, such as orthopaedic and paediatric. Searching with the term “orthop?edic” will find articles that use orthopaedic as well as orthopedic. Truncation symbols and wildcard characters vary between databases and database providers; for example, in PubMed the truncation symbol is an asterisk (∗) whereas when searching MEDLINE in Ovid it is a colon (:) or dollar sign ($). Consult each database’s online help section to determine which symbols or characters to use.


Use Boolean operators


Once you have determined the terms or phrases that you will include in your search you should consider combining your search terms using the Boolean logical operators. The Boolean AND command is used when you want all search terms to be present in each article that is retrieved. For example, when searching using ‘P’ terms and ‘I’ terms you would combine these using the Boolean AND command as you would want to retrieve articles that have both your patient/population of interest and the intervention of interest. Using our example above, your search strategy would be “(chronic low back pain) AND (operant-behavioural graded activity)”, thus narrowing your search.


The Boolean OR command is used when you want any of the specified search terms to be present in the articles. When incorporating synonyms and related terms you would search using the Boolean OR command, for example, “rheumatoid arthritis OR RA OR rheumatologic disease”, thus broadening your search. When using this search you will retrieve articles that have any one of ‘rheumatoid arthritis’ OR ‘RA’ OR ‘rheumatologic disease’. How search terms should be grouped together, that is, whether “double inverted commas” or brackets () should be used, varies between different databases, so it is useful to check this in the database’s help section.



Basics of searching—an example


To illustrate these basics of searching further we will work through a step-by-step example.



Clinical scenario


You are a rehabilitation consultant who has recently seen a number of individuals with work-related neck muscle pain, especially pain from the descending part of the trapezius muscle. You know that physical exercise is generally recommended but you do not know which type of training is more effective in relieving muscle pain—strength training of the painful muscle or general fitness training without direct involvement of the painful muscle.



Step 1: Identify the components of your question in PICO format




image


Step 2: Compose your clinical question

















Clients with work-related neck muscle pain Patients
Strength training of the painful muscle Intervention
General fitness training without direct involvement of the painful muscle Comparison
Greater pain relief Outcomes


Step 3: Construct the final clinical question







For clients with work-related neck muscle pain, does strength training of the painful muscle versus general fitness training without direct involvement of the painful muscle result in greater pain relief?


Step 4: Record keywords and phrases




image



Step 5: Identify synonyms and variant words




image


Step 6: Use truncation and wildcards where appropriate and Boolean operators to combine terms




(Neck muscle pain OR Neck strain∗ OR Neck strain injur∗ OR Neck sprain∗ OR Stiff neck OR Trapezius muscle pain) AND (Strength training OR Muscle strengthening) AND (General fitness OR Exercise) AND (Pain∗)


Note: The truncation symbol used in this example is for conducting a search in PubMed.



Step 7: Decide which online resource(s) to search


The online resource that you decide to search in will depend on the type of question that you are asking (for example, intervention, diagnostic, prognostic or qualitative question). As was explained in Chapter 2, for each type of question there is a hierarchy of evidence. This hierarchy should be used to guide your search so that you know what type of study design you are hoping to find when searching. The type of study design that you are looking for will, in turn, influence which online resource(s) you should search in. For example, if your clinical question is a prognostic one related to rehabilitation, then you will be looking for a cohort study (or systematic review of cohort studies). Therefore, there is no point in searching the Cochrane Library, PEDro or OTseeker as these resources do not contain cohort studies. The best resource for you to start your search in would probably be PubMed, using the Clinical Queries feature. All of these resources, and many others, are described in the following section and in the examples at the end of this chapter.



A model of evidence-based information services


In this chapter, we will use a five-level pyramid to discuss the organisation of evidence-based information services.2 This ‘5S’ model (see Figure 3.1) is hierarchical in nature and has:


• original studies (what was done in one study) at the base

• syntheses (what the evidence is across several studies on the same topic)—that is, systematic reviews of the literature

• synopses (what the evidence is across several studies, along with an expert telling you its strengths and potential practice changes)—that is, succinct descriptions of original studies and reviews, often accompanied by expert commentaries such as those found in evidence-based secondary journals like ACP Journal Club, Evidence-Based Medicine and Evidence-Based Nursing

• summaries—that is, management options for diseases or conditions arranged by clinical topics such as those that appear in the Physician’s Information and Education Resource (PIER) and Clinical Evidence (quite like a textbook chapter with a broad-based summary of a content area)

• systems—that is, integrated decision support services which provide evidence plus ‘actions’ that should be taken in relation to a specific client or situation.

image

FIGURE 3.1 The 5S pyramid showing levels of organisation of evidence from healthcare research


Reproduced with permission from Haynes RB, Of studies, syntheses, synopses, summaries, and systems: the “5S” evolution of information services for evidence-based healthcare decisions; American College of Physicians; 20062


As you are seeking the current best evidence, begin your search as high up in the pyramid as possible. The higher you go in the pyramid, the more the evidence has been collected, sifted and synthesised. As the synthesis and evaluation work has already been done by others, using evidence from the higher levels will save you time and labour and assist you to apply the best quality evidence that is currently available.


Deciding where to start on the pyramid depends largely on the question being asked and what resources are available to you. As explained earlier, you should be guided by the hierarchy of evidence for the type of question that you are asking. Additionally, you will also find that much of the content that is available at the higher levels of the pyramid is aimed at the medical profession and that most of the evidence for nursing and the allied health questions are found in the bottom two levels of the pyramid and, at times, level three. At each level of the ‘5S’ pyramid, users of the evidence must appraise the quality of the evidence presented ensuring that the methods used to generate this evidence were sound. Detailed information about how to critically appraise evidence, once you have found it, is presented in Chapters 4–12 of this book. Each level of the pyramid will now be discussed further, starting at the top of the pyramid, where the best and most highly synthesised evidence can be found.



Systems—first layer (top) of the pyramid


Systems are found at the top of the ‘5S’ pyramid. A system is an integrated clinical decision support service designed to improve clinical decision making. Such a system may be integrated into an electronic client health record system or hospital clinical information system. Alternatively, the system may allow for entry of client-specific characteristics, such as age, gender, renal function and allergy history. These computerised decision support systems reliably link client characteristics with the current evidence-based guidelines for care. The system generates client-specific recommendations (for example, lower the dose of insulin because of hypoglycaemic events or schedule a mammography because it is due next month). A key component of a clinical decision support service that differentiates it from other types of evidence-based information services is the integration of client-specific variables.


Clinical decision support systems have been developed for various clinical issues, including the diagnosis of chest pain, the management of chronic disease (such as diabetes care) and the timely administration of preventive services (such as immunisations). A systematic review of the effects of computerised clinical decision support systems showed that many improve health professionals’ performance.3 If you have such a system in your workplace, you are lucky as it is likely that you will not need to look further for the best evidence to answer your clinical question. However, most people will not be able to begin their search at the top of the pyramid because systems are relatively rare, existing for only a few diseases or conditions, and usually have a medical focus. Not all health professions have electronic client medical records and, even if they do, many are not integrated with a decision support system that has an evidence-based guideline summarising the current best evidence on a topic of interest. Therefore, if you do not have access to a system that addresses your information needs, you will need to start your search for the current best evidence at the next level down in the pyramid.



Summaries—second layer of the pyramid


Summaries are information resources that provide regularly updated evidence, which is usually arranged by clinical topics. They are considered to be similar to traditional textbook chapters in form and content. Evidence-based clinical guidelines are also located at this level of the pyramid. Summaries provide guidance and/or recommendations for client management and often provide links to other aspects of the disease or condition. Summaries can be found in disease-specific textbooks such as Evidence-based Endocrinology4 but, unless the textbook is accompanied by a website where the content can be regularly updated, the content in a print textbook becomes quickly outdated. Online textbooks that are regularly updated are becoming more common. Medicine has the most of these online textbooks and some of these contain information which may be of interest to allied health professionals or nurses. All of the online textbooks listed below are available on a subscription basis but many workplaces, particularly academic and healthcare institutions, may have institutional subscriptions. Examples of these online textbooks are:


• Clinical Evidence (http://clinicalevidence.bmj.com/ceweb/index.jsp) is provided by the BMJ Publishing Group and summarises evidence on the benefits and harms of healthcare interventions for selected medical conditions. The evidence is drawn from systematic reviews and original studies. The content is presented in question format (for example, what are the effects of interventions aimed at reducing relapse rates and disability in people with multiple sclerosis?), with the levels of evidence used to answer the question and hyperlinks to the supporting evidence. A clinical guide (that is, a comment on how to use this information in clinical practice) is also presented.

• Physician’s Information and Education Resource (PIER) (http://pier.acponline.org/index.html), from the American College of Physicians (ACP), is an integrated summary service that provides evidence-based guidance and practice recommendations for health professionals. It is organised into seven topic types (diseases, screening and prevention, complementary and alternative medicine, ethical and legal issues, procedures, quality measures and drug resources), with each topic containing several modules. PIER’s authors are supported by an explicit evidence-based process, where current best evidence is provided to the authors of the chapters after comprehensive literature searches are conducted.

PIER is available online to ACP members but it can be accessed through STAT!Ref (http://www.statref.com/), an online healthcare reference that provides full text access to key medical reference sources and textbooks, some of which are evidence-based resources. STAT!Ref is a subscription-based resource that is usually available in academic or hospital environments where institutional subscriptions exist. PIER is more directive than Clinical Evidence as it contains recommendations rather than evidence summaries.


• Up To Date (http://www.uptodate.com/) is an online textbook that is very comprehensive in its topic coverage. It is currently organised into 16 medical specialties (for example, adult primary care and internal medicine, cardiovascular medicine, endocrinology and diabetes, family medicine). UpToDate provides specific recommendations (guidelines) for health professionals for client care and most, but not all, of these recommendations include an assessment of the quality of the evidence.

• First Consult (http://www.mdconsult.com/das/pdxmd/lookup/87695189-2?type=med) is part of MD Consult, from Elsevier, and is an evidence-based and continuously updated clinical information resource for primary care clinicians. Designed for use at point-of-care (for example, at the bedside, in the clinic), information is arranged around the components of medical topics, differential diagnosis and procedures. Recommendations are made but neither the levels of evidence nor links to supporting evidence accompany each recommendation.

• EBM Guidelines: Evidence Based Medicine (http://ebmg.wiley.com/ebmg/ltk.koti), from Wiley Interscience, is a collection of clinical guidelines for primary care combined with the best available evidence. There are approximately 1000 primary care practice guidelines, which are continuously updated and cover a wide range of medical conditions. Both diagnosis and treatment are included.


Synopses—third layer of the pyramid


If you do not find an answer to your clinical question in a summary, the next best place to search for an answer is in a synopsis. Synopses are structured abstracts or brief overviews of published individual studies and systematic reviews that have been screened for methodological rigour. This means you do not have to do this step yourself! Synopses can be found in the following online resources:


• ACP Journal Club (http://www.acpjc.org/), Evidence-Based Medicine (http://ebm.bmj.com/) and Evidence-Based Nursing (http://ebn.bmj.com/) are pre-appraised, secondary journals that are available online as well as in print. To produce the content for these journals, research staff hand-search over 130 core healthcare journals and critically appraise the articles in each issue to identify high quality primary studies and review articles that have potential for clinical application. From this pool of articles, practising health professionals rate the content for relevancy and newsworthiness. The studies and reviews that are considered to be the most clinically important are summarised in structured abstracts. A clinical expert comments on the methods and provides a clinical bottom line (that is, how to use the evidence in clinical practice). The focus of the content in ACP Journal Club is internal medicine and it includes sections on therapy, diagnosis, prognosis, aetiology, quality improvement and continuing education, economics, clinical prediction guides and differential diagnosis. The focus of the content in Evidence-Based Medicine is general medical practice and includes the same sections as ACP Journal Club (for example, therapy, diagnosis etc). The focus of the content in Evidence-Based Nursing is nursing and includes the same sections as ACP Journal Club and Evidence-Based Medicine with an additional section that contains articles of a qualitative nature. These evidence-based journals are subscription-based resources. ACP Journal Club is also one of the databases available through Ovid (http://gateway.ovid.com/), a company that designs search engines and makes several evidence-based databases available on a subscription basis. Many institutions such as libraries, hospitals and universities use Ovid and therefore have institutional subscriptions.

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Related posts:

  1. Introduction to evidence-based practice
  2. Evidence about diagnosis
  3. Questions about the effects of interventions: examples of appraisals from different health professions
  4. Talking with clients about evidence

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Mar 21, 2017 | Posted by in MEDICAL ASSISSTANT | Comments Off on Finding the evidence

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