Showing papers by "Deborah J. Cook published in 1997"

Systematic Reviews: Synthesis of Best Evidence for Clinical Decisions

Abstract: Systematic reviews can help practitioners keep abreast of the medical literature by summarizing large bodies of evidence and helping to explain differences among studies on the same question. A systematic review involves the application of scientific strategies, in ways that limit bias, to the assembly, critical appraisal, and synthesis of all relevant studies that address a specific clinical question. A meta-analysis is a type of systematic review that uses statistical methods to combine and summarize the results of several primary studies. Because the review process itself (like any other type of research) is subject to bias, a useful review requires clear reporting of information obtained using rigorous methods. Used increasingly to inform medical decision making, plan future research agendas, and establish clinical policy, systematic reviews may strengthen the link between best research evidence and optimal health care.

The relation between systematic reviews and practice guidelines.

Abstract: Clinical practice guidelines have been developed to improve the process and outcomes of health care and to optimize resource utilization. By addressing such issues as prevention, diagnosis, and treatment, they can aid in health care decision making at many levels. Several other decision aids are cast in the guideline lexicon, regardless of their focus, formulation, or format; this can foster misunderstanding of the term "guideline." Whether created or adapted locally or nationally, most guidelines are an amalgam of clinical experience, expert opinion, and research evidence. Approaches to practice guideline development vary widely. Given the resources required to identify all relevant primary studies, many guidelines rely on systematic reviews that were either previously published or created de novo by guideline developers. Systematic reviews can aid in guideline development because they involve searching for, selecting, critically appraising, and summarizing the results of primary research. The more rigorous the review methods used and the higher the quality of the primary research that is synthesized, the more evidence-based the practice guideline is likely to be. Summaries of relevant research incorporated into guideline documents can help to keep practitioners up to date with the literature. Systematic reviews have also been published on the dissemination and implementation strategies most likely to change clinician behavior and improve patient outcomes. These can be useful in more effectively translating research evidence into practice.

Evidence-Based Disease Management

Abstract: Disease management is an approach to patient care that emphasizes coordinated, comprehensive care along the continuum of disease and across health care delivery systems. Evidence-based medicine is an approach to practice and teaching that integrates pathophysiological rationale, caregiver experience, and patient preferences with valid and current clinical research evidence. Using diabetes mellitus as an example, we describe the importance of evidence-based medicine to the development of disease management programs. We present a method for developing and implementing evidence-based clinical guidelines, clinical pathways, and algorithms and describe the creation of systems to measure and report processes and outcomes that could drive quality improvement in diabetes care. Multidisciplinary teams are ideally suited to develop, lead, and implement evidence-based disease management programs, since they play an essential role in the preventive, diagnostic, and therapeutic decisions for patients with diabetes throughout the course of their disease.

A guide to interpreting discordant systematic reviews

Abstract: Systematic reviews are becoming prominent tools to guide health care decisions. As the number of published systematic reviews increases, it is common to find more than 1 systematic review addressing the same or a very similar therapeutic question. Despite the promise for systematic reviews to resolve conflicting results of primary studies, conflicts among reviews are now emerging. Such conflicts produce difficulties for decision-makers (including clinicians, policy-makers, researchers and patients) who rely on these reviews to help them make choices among alternative interventions when experts and the results of trials disagree. The authors provide an adjunct decision tool--a decision algorithm--to help decision-makers select from among discordant reviews.

Users' Guides to the Medical Literature: XII. How to Use Articles About Health-Related Quality of Life

Abstract: CLINICAL SCENARIO You are a physician following a 35-year-old man who has had active Crohn disease for 8 years. The symptoms were severe enough to require resectional surgery 4 years ago, and despite treatment with sulfasalazine and metronidazole, the patient has had active disease requiring oral steroids for the last 2 years. Repeated attempts to decrease the prednisone have failed, and the patient has required doses of greater than 15 mg per day to control symptoms. You are impressed by both the methods and results of a recent article1documenting that such patients benefit from oral methotrexate and suggest to the patient that he consider this medication. When you explain some of the risks of methotrexate, particularly potential liver toxicity, the patient is hesitant. How much better, he asks, am I likely to feel while taking this medication? INTRODUCTION There are 3 reasons we offer treatment to our patients.

Central venous catheter replacement strategies: A systematic review of the literature

Abstract: Objective To evaluate the effect of guidewire exchange and new-site replacement strategies on the frequency of catheter colonization and infection, catheter-related bacteremia, and mechanical complications in critically ill patients.Data Sources We searched for published and unpublished research by

Effect of noninvasive positive pressure ventilation on mortality in patients admitted with acute respiratory failure: a meta-analysis.

Abstract: Objective To critically appraise and summarize the trials examining the addition of noninvasive positive pressure ventilation to standard therapy on hospital mortality and need for endotracheal intubation in patients admitted with acute respiratory failure. Data Sources We searched MEDLINE (1966 to September 1995) and key references were searched forward using the Scientific Citation Index (SCISEARCH). Bibliographies of all selected articles and review articles were examined. Authors of all selected and review articles were contacted by letter to identify unpublished work. Study Selection a) Population: patients with acute respiratory failure; b) intervention: noninvasive positive pressure ventilation; c) outcome: mortality and/or endotracheal intubation; and d) design: randomized, controlled study. Two of us independently selected the articles for inclusion; disagreements were settled by consensus. Seven (three unpublished) of 212 initially identified studies were selected. Data Extraction Two authors independently extracted data and evaluated methodologic quality of the studies. Data Synthesis Noninvasive positive pressure ventilation was associated with decreased mortality (odds ratio = 0.29; 95% confidence interval 0.15 to 0.59) and a decreased need for endotracheal intubation (odds ratio = 0.20; 95% confidence interval 0.11 to 0.36). Sensitivity analysis suggested a greater benefit of noninvasive positive pressure ventilation in patients with chronic obstructive pulmonary disease (COPD). The inclusion/exclusion of unpublished trials did not influence these results. Conclusions The addition of noninvasive positive pressure ventilation to standard therapy in patients with acute respiratory failure improves survival and decreases the need for endotracheal intubation. However, this effect is restricted to patients whose cause of acute respiratory failure is an exacerbation of COPD. Further research is warranted to determine whether noninvasive positive pressure ventilation confers benefit in patients without COPD who have acute respiratory failure. (Crit Care Med 1997; 25:1685-1692)

Systematic Reviews: Critical Links in the Great Chain of Evidence

Abstract: Successful clinical decisions, like most human decisions, are complex creatures [1]. In making them, we draw on information from many sources: primary data and patient preferences, our own clinical and personal experience, external rules and constraints, and scientific evidence (Figure 1). The mix of inputs to clinical decisions varies from moment to moment and from day to day, depending on the decision and the decision makers. In general, however, the proportion of scientific evidence in the mix has grown progressively over the past 150 years or so. Figure 1. Factors that enter into clinical decisions. One major reason why the mix has changed is simply the explosive increase in the amount and quality of the scientific evidence that has come from both the laboratory bench and the bedside. The maelstrom of change wrought by the molecular biology revolution has been matched at the clinical level by a tidal wave of increasingly sophisticated clinical trials. It is estimated that since the results of the first randomized clinical trials in medicine were published in the 1940s [2], roughly 100 000 randomized and controlled clinical trials have appeared in print [3], and the results of many well-conducted, completed trials remain unpublished [4]. A second reason for the growing emphasis on scientific evidence is the increasing expectation, from both within and outside of the medical profession, that physicians will produce and use the evidence in delivering care. The future holds the promise of continued expansion of the body of research information. However, it also holds the parallel threat of increasingly inadequate time and resources with which to find, evaluate, and incorporate new research knowledge into everyday clinical decision making. Fortunately, mechanisms are emerging that will help us acquire the best, most compelling, and most current research evidence. Particularly promising in this regard is the use of systematic reviews. Systematic reviews are concise summaries of the best available evidence that address sharply defined clinical questions [5, 6]. Of course, the concept of reviews in medicine is not new. Preparation of reviews has traditionally depended on implicit, idiosyncratic methods of data collection and interpretation. In contrast, systematic reviews use explicit and rigorous methods to identify, critically appraise, and synthesize relevant studies. As their name implies, systematic reviews-not satisfied with finding part of the truth-look for the whole truth. That is, they seek to assemble and examine all of the available high-quality evidence that bears on the clinical question at hand. Although it looks easy from the outside, producing a high-quality systematic review is extremely demanding. The realization of how difficult the task is should be reassuring to all of us who have been frustrated by our seeming inability to stay informed and up to date by combing through the literature ourselves. The concepts and techniques involved, including that of meta-analysis, are at least as subtle and complex as many of those currently used in molecular biology. In this connection, it is important to understand that a systematic review and a meta-analysis are not one and the same. Meta-analysis is a specific methodologic and statistical technique for combining quantitative data. As such, it is simply one of the tools-albeit a particularly important one-that is used in preparing systematic reviews. Although many of the techniques involved in creating a systematic review have been widely available for some time, the techniques for generating clinical recommendations that consider baseline risk, cost, and the totality of the evidence available from a systematic review constitute a relatively new area of research that requires dealing with a range of critical yet abstract issues, such as ambiguity, context, and confidence. Many articles describing the conceptual basis of systematic reviews have been published during the past decade [7], but detailed, how-to information on preparing, understanding, and using systematic reviews has been scattered and incomplete. The forthcoming series of articles on systematic reviews that begins with the paper by Cook and colleagues in this issue [8] has been designed to collate and update that information. Cook and colleagues describe systematic reviews in detail, discuss their strengths and limitations, and explain how they differ from traditional, narrative reviews. The remainder of the papers in the series are divided into two categories: using systematic reviews in practice and conducting reviews. These articles are primarily broad narrative overviews. In preparing them, their authors have drawn on widely varying sources, including electronic searches of the published literature, reference lists, the Cochrane Library [3], personal files, colleagues, and personal experience. Most of the articles are directed toward practitioners who wish to learn more about what systematic reviews are and how to use them. A few are directed primarily toward specific audiences, such as physician-educators. And we hope that the last articles in the series will entice some readers to join the growing number of groups that are doing the hard but intensely rewarding work of preparing systematic reviews. Some of the articles inevitably delve into technical and seemingly arcane methodologic topics, but we make no apologies for this. Medicine at all levels is technical, and pushing the envelope inevitably involves moving out into unfamiliar and sometimes uncomfortable territory. Perhaps more important, however, is that many aspects of the systematic review process will be familiar to clinicians because these techniques are similar to the ones they use every day: collecting, filtering, synthesizing, and applying information. How can the full potential of the knowledge contained in systematic reviews be realized in clinical practice? There is no simple answer, but the following would help. First, developers of electronic databases must, at the very least, pioneer improved-that is, more transparent and clinically meaningful-approaches to searching, thereby giving physicians rapid, sensitive, and specific access to multiple data sources. Second, we need many more systematic reviews that address the natural history and diagnosis of disease and the benefits and potential harms of health care interventions. Third, we need to champion the production of new, well-designed, high-quality research that evaluates important patient outcomes-the raw material of systematic reviews that is a crucial part of clinical decision making. And, finally, both physicians and the health care systems in which we work need to fully embrace and tangibly support lifelong learning as an essential element in the practice of good medicine. A recent related development is an international movement to improve the reporting of clinical research, particularly the results of randomized, controlled trials [9] and meta-analyses [10]. These efforts focus on clear, comprehensive communication of the methods and results of clinically relevant research through the development and application of reporting standards that are being suggested by editors, researchers, methodologists, and consumers. These standards should allow readers to better appraise, interpret, and apply the information in published reports of research in their own practices and situations. Perhaps equally important is the possibility that these standards will create a positive ripple effect, starting at the earliest stages of research planning and extending through the conduct of clinical trials. Exciting new information pouring out of the molecular biology revolution has the potential to transform medicine. But even this enormously powerful information will be of little use to physicians and their patients unless 1) the diagnostic and therapeutic interventions that flow from it are stringently tested in clinical trials and 2) the results of those trials are synthesized and made accessible to practitioners. Systematic reviews are thus a vital link in the great chain of evidence that stretches from the laboratory bench to the bedside. From this perspective, the awesome task of extracting the knowledge already encoded in the tens of thousands of high-quality clinical studies, published and unpublished, is arguably every bit as important to our health and well-being as the molecular biology enterprise itself. The task can only grow in size and importance as more and better trials are conducted; indeed, the task has already been likened in scope and importance to the Human Genome Project [11]. It is our earnest hope that these articles on systematic reviews will play a useful part in strengthening the chain of evidence that links research to practice. Dr. Cook: Department of Medicine, St. Joseph's Hospital, 50 Charlton Avenue East, Hamilton, Ontario L8N 4A6, Canada. Dr. Davidoff: Annals of Internal Medicine, American College of Physicians, Independence Mall West, Sixth Street at Race, Philadelphia, PA 19106.

Single Daily Dosing of Aminoglycosides in Immunocompromised Adults: A Systematic Review

Abstract: We examined the efficacy and toxicity of single daily dosing (SOD) of aminoglycosides for febrile, immunocompromised adults by systematically reviewing four randomized, controlled trials of SOD vs standard dosing regimens We assessed the methodological quality of each study and extracted data pertaining to efficacy and toxicity outcomes Pooled risk ratios for the efficacy outcomes were bacteriologic cure, 100 (95% confidence interval [ell, 086-116); clinical cure, 097 (95% CI, 091-105); and mortality, 093 (95% CI, 062-141) The pooled nephrotoxicity risk ratio was 078 (95% CI, 031-194) Only one study assessed ototoxicity Although our study was limited by the small number of trials available for review, the results suggest that SOD of aminoglycosides may be efficacious for febrile, immunocompromised patients Additional studies are necessary for more precise quantification of the mortality and toxicity risk ratios Aminoglycoside antibiotics have traditionally had an ad­ junctive, synergistic role in the empirical treatment of febrile, neutropenic patients [1-3] Consensus guidelines and proposed algorithms for these empirical regimens have included recom­ mendations that aminoglycosides be combined with {3-lactam antibiotics to provide adequate coverage for infections due to {3-lactam-resistant gram-negative organisms [4] Specific treatment guidelines for febrile neutropenic patients recom­ mend early combination therapy with an aminoglycoside for patients with severe granulocytopenia (granulocyte count, 7 days), and/or the presence of a clinical focus of infection [5] How­ ever, the reported efficacy of {3-lactam monotherapy, which is equal to that of synergistic antibiotic combinations, and concern regarding the toxicity of the combination regimens have limited the widespread use of aminoglycosides in this population [6]

Current Guidelines on Stress Ulcer Prophylaxis

Abstract: Acute upper gastrointestinal bleeding in intensive care unit (ICU) patients may occur due to peptic ulcer disease, adverse drug effects, gastric tube lesions, acute renal failure, liver failure or stress-induced gastric mucosal lesions. Gastric acid hypersecretion can be observed in patients with head trauma or neurosurgical procedures. Gastric mucosal ischaemia due to hypotension and shock is the most important risk factor for stress ulcer bleeding.

How to use diagnostic test articles in the intensive care unit: diagnosing weanability using f/Vt.

Abstract: Medical diagnosis involves generating a set of hypotheses and obtaining information that modifies these hypotheses. Sources of this information include the history, physical examination, and laboratory investigations, all of which function as diagnostic tests. Studies of diagnostic tests are useful when a) the population under study is representative of those to whom we would like to apply the results; b) when an independent, blind comparison is made of the test results with a reference standard; and c) when the reference standard is performed on all patients, rather than restricted to those patients with particular test results. Clinicians can use the data from such high quality studies in the form of sensitivity and specificity, as well as likelihood ratios, which indicate the direction and magnitude of the change in probability of a target condition from pretest to posttest. Study results will be more easily applicable to practice when the performance and interpretation of the test is similar in study and clinical settings. We conduct diagnostic tests primarily to improve the process of patient care and patient outcome, and test ordering behavior ideally reflects these goals.

Transferring evidence from research into practice: 3. Developing evidence-based clinical policy

Abstract: In previous editorials in this series (1, 2), we described a path that leads from health care research evidence to evidence-based health care. The steps include getting the evidence straight, developing evidence-based clinical policy, and then applying the policy.

Transferring evidence from research into practice: 4. Overcoming barriers to application.

Abstract: In the 3 preceding essays in this series (1–3), we described a path that leads from health care research evidence to evidence-based health care. The steps include getting the evidence straight, developing evidence-based clinical policy, and then applying the policy. In this editorial, we focus on the final step, applying evidence-based policy in the right way at the right place and time. As a precondition, application efforts are only justified if the evidence on which they are based is up to date and has been accurately incorporated and if the policy to be applied achieves a workable balance between both the evidence from research and the circumstances in which the evidence must be applied.

How to use articles about harm: the relationship between high tidal volumes, ventilating pressures, and ventilator-induced lung injury.

Abstract: BACKGROUND Intensivists commonly encounter patients who may be inadvertently harmed by critical care interventions This article is designed to guide clinicians in the evaluations of an individual article assessing a question of harm, as well as the sum of multiple pieces of evidence OBJECTIVES To assess the vaidity of a group of articles about the relationship between high tidal volumes and ventilating pressures on ventilator-induced lung injury; to interpret the results of these studies; and to consider whether they apply in practice DATA SOURCES Issues of harm are sometimes measured in randomized trials, but are evaluated more often in myriad observational studies DATA EXTRACTION We use critical appraisal guides for experimental studies (eg, randomized trials) and observational studies (eg, cohort studies, case-control studies and case series) that evaluate the potentially harmful exposure of high tidal volumes and ventilating pressures This involves assessing the validity of the research, then determining the strength of association between the putative harmful exposure and adverse outcomes These study designs and their interpretation using relative risks and odds ratios are reviewed Finally, the relevance of this information (or lack thereof) to clinical practice needs to be determined DATA SYNTHESIS Examining these studies individually and in totality, there appears to be a relationship between high tidal volumes and ventilating pressures, although the strength of inference from this research is limited by design issues and sample sizes CONCLUSIONS Critically appraising a body of literature is more challenging than evaluating a single study, but often gives a broader view of the available evidence Future large, rigorous, randomized trials of different approaches to mechanical ventilation will help to advance our understanding and to better inform our practice

Diagnostic accuracy of a rural live video telepathology system.

Abstract: Accuracy of diagnoses rendered using a live video telepathology network was assessed for permanent sections of surgical pathology specimens. To determine accuracy, telepathology diagnoses were compared with those obtained by directly viewing the glass slide using a standard microscope. A total of

How to use an article on therapy or prevention: pneumonia prevention using subglottic secretion drainage.

Abstract: Evidence based critical care medicine involves integrating clinical experience, expertise, and patient preferences with explicit, systematic, and judicious use of current best evidence in making medical decisions. Published evidence has many sources: research from the basic sciences of medicine, and from patient-centered clinical research on the accuracy of diagnostic tests, the power of prognostic markers, and the effectiveness and safety of preventive, therapeutic, rehabilitative, and palliative interventions. When critically appraising a clinical article for potential use in intensive care unit (ICU) practice, the first question we ask ourselves is: Is this study valid? If examination of the study methods reveals that the design is rigorous, we can turn to the two other key questions: What are the results? and, Will the results help me care for my patients? This approach may aid in the interpretation of an article on therapy or prevention; in it we discuss a strategy designed to prevent ventilator associated pneumonia in critically ill patients.

Systematic review: The relation between nutrition and nosocomial pneumonia: randomized trials in critically ill patients

Abstract: Objective To review the effect of enteral nutrition on nosocomial pneumonia in critically ill patients as summarized in randomized clinical trials.

Health professional decision-making in the ICU: a review of the evidence.

Abstract: End-of-life decisions in the ICU are often complex and emotionally charged. Intensivists can correct the physiologic abnormalities of acute and chronic illness with drugs and technology, and prolong life in many situations. Understanding and attending to the psychological and emotional needs of not only patients but also their families are part of the delivery of compassionate critical care. The process of communicating and decision-making on the ICU team and in family units has been a domain of active research over the past decade. Studies on do-not-resuscitate orders, and advanced and delayed directives comprise a portion of this work. This article contains a brief summary of selected research evidence on these difficult end-of-life issues.

An evidence-based approach to the clinical examination.

Abstract: The history and physical examination of a patient remain the cornerstones of clinical medicine. Without an adequate history and physical examination to suggest possible differential diagnoses, the subsequent investigations of the patient may be endless (and fruitless). Although we rely heavily on the clinical examination, until recently there has been little formal evaluation of the information gained from these clinical encounters. A series entitled “The Rational Clinical Exam” in the Journal of the American Medical Association is now making a key contribution to our understanding by critiquing and summarizing the value of the evidence obtained during the initial patient-clinician encounter.1 In each encounter, we gather information that aids us in establishing a relationship with our patients, generating diagnoses, estimating prognoses, and initiating and monitoring our patients’ response to therapy. Generating diagnoses is an iterative process that includes information gathering and hypothesis generation. Data acquisition may begin with the chief complaint, history of present illness, past medical history, and findings from the physical examination. Information gathered at any stage in the clinical examination may be sufficient for hypothesis generation and a partial diagnosis that prompts action. With each new piece of information, the diagnoses that are considered, and their relative likelihoods, may change. Thus, we can consider components of the history and physical examination as individual diagnostic tests, from which sequential information is obtained that helps to rule in or rule out specific diagnoses. As with laboratory diagnostic tests, when considering relevant clinical skills as diagnostic tests, we must understand their properties of reliability and accuracy, and the appropriate use of likelihood ratios (LRs). To illustrate how the history and physical examination are used as diagnostic tests, we will follow a patient through an encounter with a general internist. Our clinical focus will be the diagnosis of cerebrovascular and peripheral vascular disease. At each step of the interaction, we will highlight the relevant clinical skills literature and the related diagnostic test properties, and demonstrate how application of this evidence increases the physician’s understanding of the patient’s problems, and guides subsequent management decisions.

Attitudes toward the use of gender-inclusive language among residency trainees

Abstract: Objective: To explore postgraduate medical trainees’ attitudes toward the use of gender-inclusive language. Design: Self-administered questionnaire. Setting: Seven residency training programs at McMaster University, Hamilton, Ont., from July 1993 to June 1994. Participants: Of 225 residents in the programs, 186 responded to the survey, for a response rate of 82.7%. Men and women were equally represented among the respondents. Outcome measures: Categorization of attitudes about the use of language as gender-inclusive or gender-exclusive; characteristics predicting a gender-inclusive attitude. Results: Factor analysis and Cronbach’s α (0.90) supported the existence of a construct related to attitudes about language use, the poles of which were categorized as gender-inclusive and gender-exclusive. The authors classified residents with respect to their attitudes to language use from their responses to the questionnaire. In univariate analyses, sex, residency program and country of graduation significantly predicted a gender-inclusive attitude (p < 0.01). Only the first 2 variables were significant in a multivariate model; residency program explained 18% of the variance and sex 3%. Residents in obstetrics and gynecology and psychiatry had the most gender-inclusive attitudes, whereas residents in surgery and anesthesia had the most gender-exclusive attitudes. Conclusions: Residents’ values are reflected in the language they choose to use. Language use may provide an index of underlying attitudes that may create hostile environments for female trainees. Resume Objectif : Explorer les attitudes des stagiaires en medecine au niveau postdoctoral