Digestible EBM Teaching Slices: Tactics to Regularly Feed Your Residents

Transcription

1 Digestible EBM Teaching Slices: Tactics to Regularly Feed Your Residents Objectives: 1. Explore practical approaches to weave best evidence into your clinical teaching 2. Tackle commonly challenging EBM concepts 3. Gain a healthy swagger at the intersection of EBM content knowledge and its application during clinical teaching 4. Enjoy Fun Interaction 5. Provide Resources to Bolster Your Skills Top Strategies to Integrate EBM Practical Glossary of Terms Selected EBM Bibliography As Chief Residents, you will have a tremendous range of patient-based teaching opportunities from wards to clinics to case conferences in which to precipitate greater progress in making EBM a practical reality for residents. This workshop will address quick use and interpretation of evidence-based resources through real teaching opportunities. In a highly interactive fashion, we will emphasize and role-model specific teaching tactics necessary for success in time-pressured settings particularly showcasing the judicious use of teaching slices and a fearlessness to integrate best evidence from clinical research alongside other educational priorities. Attached are a few slides to give you a taste of the issues we will be addressing. Because some of our methodology necessitates discovering key learning points, the final powerpoint presentation will be posted on the APDIM website after the meeting. April 19, 2016

2 Digestible EBM Teaching Slices: Tactics to Regularly Feed Your Residents Joseph F. Szot, MD Associate Program Director Mark C. Wilson, MD, MPH Associate Dean, Graduate Medical Education University of Iowa Carver College of Medicine APDIM April 19, 2016 Core Principles of Evidence-Based Clinical Practice The better the overall research, the more confident our clinical decisions Evidence alone is never sufficient to make clinical decisions

3 EBM: What it is Evidence-Based Medicine is about solving clinical problems. Users Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice, 2008 Let s Venture into Urgent Care We re going in deep into this CR s head He s moonlighting in urgent care clinic Current patient asked him why he wasn t prescribing a therapy

4 What if I don t know the answer to their questions? Affective Responses Losing Control Embrace that c/w Adaptive Expertise Allows experts to continuously learn during the process of problem-solving Unanticipated challenges become opportunities for learning Academic Medicine 87: 1-5, 2012 So Let s Study a Few Slices

5 Ask Acquire Patient Dilemma Evidence Cycle of EBM Action Appraise Apply You re Precepting in Clinic

6 What Did You Notice that Will Help You Back Home? Ask Patient Dilemma Action Acquire Evidence Cycle of EBM Appraise (a) Epi Content Apply

7 You re Cranking Out Notes on the Wards Consider What Mark Did What Specifically Could You Try Back Home?

8 Use Teaching Tips Scripts (in CMAJ & now JGIM and web-based) Richardson WS & Wilson MC. Tips for Teachers of EBM: Making Sense of Diagnostic Test Results Using Likelihood Ratios. JGIM 2007; 23:87-92 Others covering: RRR, ARR, NNT Confidence Intervals Kappa Heterogeneity Ask Patient Dilemma Action Acquire Evidence Cycle of EBM Appraise (b) Interpretation Apply

9 You re Curb-Sided by a Resident with Insecurity Time to Start Coaching

10 Finishing up a Case in M&M

11 Nonsteroidal anti-inflammatory drugs for prevention of post- ERCP pancreatitis: a meta-analysis Gastrointestinal Endoscopy 2012; 76(6): Figure 2 Forest plot demonstrating significant decrease in overall incidence of post- ERCP pancreatitis with prophylactic NSAID Follow-up on Wards: Colchicine & Acute Pericarditis

12 Finishing up the First Case in Ambulatory Morning Report

13 Does This Patient Have a Torn Meniscus or Ligament of the Knee? The Rational Clinical Examination Copyright American Medical Association. All rights reserved. JAMA The McGraw-Hill Companies, Inc. Lachman Test A positive test End point not discrete, or Increased anterior tibial translation The Rational Clinical Examination Copyright American Medical Association. All rights reserved. JAMA The McGraw-Hill Companies, Inc.

14 LRs: Ligament Specific Test LR+ (95% CI) LR (95% CI) Lachman test 42 ( ) Anterior drawer test 3.8 (0.7-22) 0.1 (0-0.4) 0.3 ( ) The Rational Clinical Examination Copyright American Medical Association. All rights reserved. JAMA The McGraw-Hill Companies, Inc. Patient Dilemma Ask Action Acquire Evidence Cycle of EBM Appraise Apply

15 You re Getting Ready to Start the Day in Clinic with the Ambulatory Block Resident

16 Acupuncture and related interventions for smoking cessation Figure 1. Acupuncture vs sham acupuncture, early smoking cessation Cochrane Database of Systematic Reviews Published by John Wiley & Sons, Ltd

17 Acupuncture and related interventions for smoking cessation Figure 2. Acupuncture vs sham acupuncture, smoking cessation at 6-12 months Cochrane Database of Systematic Reviews Published by John Wiley & Sons, Ltd What Specifically Went Well with this Teaching Opportunity?

18 Reflect for a Moment About what we ve covered today and how you d like to put some of it into ACTION On the Carbon-less Paper, Jot Down how specifically you want to integrate more EBM into: On the Fly Opportunities Patient-Based Seminars Take the white copy to remind yourself Leave us the yellow copy

19 Top Strategies to Weave EBM into Your Clinical Teaching Mark C. Wilson, MD, MPH, Associate Dean, GME, University of Iowa W. Scott Richardson, MD, Associate Dean, Curriculum, University of Georgia I. To Teach EBM, You MUST USE IT in Your Own Clinical Practice This common sense point is often forgotten. Your confidence will grow as you pursue your own learning issues that are tied to the care of your patients. This repetitive process and the answers you find will help you build a growing cache of evidence-based answers for recurring issues. You ll also become familiar with where your learners might stumble or get stuck when solving a problem these can actually yield very engaging opportunities to teach them how to get unstuck. II. Assess Your Learner s EBM Readiness Your enthusiasm to teach EBM may not be matched by your learner s ability to swallow what you present. Quickly assess what their day is like and where they are with their EBM skills so that you can judiciously choose what & when to teach. III. Diagnose Both the Patient and the Learner This involves listening carefully during the case presentation, attending first to what s wrong with the patient, and then concentrating on how well the learner understands the patient s illness. Doing this well helps you focus teaching with evidence on the relevant clinical needs of the patient AND the learning needs of your resident. IV. Find and Build Their Questions from the Case Start with the main decision being made and consider what knowledge you and the resident most need to make that decision wisely. Knowledge needs often remain muddled in a silent ruminating stage. Help the resident articulate them, often by initially labeling the type of issue (e.g. differential diagnosis; therapy) with which they are wrestling. Then together sculpt a well-built clinical question by delving deeper into more specifics like which patients, which interventions, which outcomes, etc. V. Select Which Clinical Question(s) to Pursue We usually have more questions than time, so don t let your residents feel paralyzed by all that they don t know. Help them choose wisely which ones to answer. Select the issue that is most relevant to this patient and this learner now, considering also what is most urgent, interesting, feasible to answer, and/or likely to recur. VI. Match Questions to Specific Information Resources Since many learners haven t been exposed yet to which resources have the highest yield for various types of questions, try doing this step out loud by coaching them on how to prioritize reasonable and available options. APDIM Chief Resident Workshop April 2016

20 VII. Cultivate Curiosity by Showing Your Own and Celebrate It in Others Saying I don t know and then pursuing and sharing what you ve learned are powerful examples for your residents. Be explicit as you articulate your own uncertainty and questions and your enthusiasm will become contagious. VIII. Balance EBM Excursions with Teaching Other Doctoring Skills Remember that your residents need background knowledge, clinical skills, and EBM. Address them all and they will respect you as a clinically relevant teacher. IX. Bite Off Less than You Can Chew Accept that time limitations exist. It s OK and advisable to teach digestible slices of evidence-based teaching. Modulate your teaching plans based on the learner s needs/receptivity as well as based on their clinical load. X. Use Pre-Appraised Evidence Resources These include electronic synopses of evidence like ACP Journal Club, BMJ Clinical Evidence, and Cochrane Reviews which are feasible to obtain and use quickly at the point of care. Also other syntheses like well-constructed clinical practice guidelines typically include appraisal of best available evidence. XI. Emphasize Interpreting & Applying Evidence in Decision-Making Help your residents get to this pay-off or learning reward as often as possible. Explicitly role model how you are integrating the evidence alongside other important aspects of your clinical decisions. XII. Put It in English Jargon terms can be stumbling blocks for our residents. Try to explain the concept first, and then label it with the term afterward. Also help learners translate study results into meaningful English statements for their colleagues and patients. XIII. Go Fishin in Lakes You Know are Stocked and also in New Lakes You ll gain confidence quickly if you engage residents in issues about which you already know that high-quality evidence exists. And as with your own clinical practice don t forget to role-model the process of identifying and filling new knowledge gaps about problems for which you don t know if helpful evidence exists. XIV. Exploit the Learning Opportunity NOT the Learner As you encourage your residents to show you their knowledge gaps, don t leave them feeling that you re just playing Whack-a-Mole. Make sure you share the responsibility for tracking down and reporting back with the best evidence. XV. Be Fearless! Just Do It! Start weaving a more evidence-based approach into your clinical teaching well before you ve developed total mastery. Just Start Somewhere and then build your knowledge, skills, and confidence from there. APDIM Chief Resident Workshop April 2016

21 Evidence-Based Medicine: A Selected Bibliography 1 Selected How To Books & a couple editorials: 1. Straus SE, Richardson WS, Glasziou P, Haynes RB, eds. Evidence-Based Medicine: How To Practice And Teach EBM, 4 th Edition. New York, Churchill Livingstone, Cook, DJ, Guyatt, G, Meade, MO, Rennie, D. Users Guide to Medical Literature: A Manuel for Evidence-Based Clinical Practice. 3 rd Ed. New York, NY: McGraw Hill; Strauss SE, et al. Misunderstandings, Misperceptions, and Mistakes. ACP JClub 2007; 146:A Montori VM, Guyatt GH. Progress in Evidence-Based Medicine. JAMA 2008; 300: Jackson R, et al. The GATE Frame : Critical Appraisal with Pictures. ACP J Club 2006; 144: A Schwartz MD, et al. Improving Journal Club Presentations, or, I can present that paper in under 10 minutes. ACP J Club 2007; 147: A8-9. Asking Answerable Clinical Questions 1. Richardson WS, Wilson MC, Nishikawa J, Hayward RSA. The well-built clinical question: a key to evidence-based decisions [Editorial]. ACP J Club 1995 Nov-Dec; 123: A12 A Richardson WS. Ask, and ye shall retrieve. Evidence-Based Medicine 1998; 3: McKibbon KA, Richardson WS, Walker Dilks C. Finding answers to well built clinical questions [Editorial]. Evidence-Based Medicine 1999; 6: Acquiring Evidence: 1. PubMed tutorial at National Library of Medicine: Appraising & Understanding Evidence: Select and apply the relevant Users Guides; also, some additional resources are: 1. Grimes DA, Schulz KF. An overview of clinical research: the lay of the land. Lancet 2002 Jan 5; 359: Applying Evidence to Clinical Decisions: APDIM April 2016

22 2 1. Glasziou PP, Irwig LM. An evidence-based approach to individualising treatment. Br Med J 1995; 311: Cook RJ, Sackett DL. The number needed to treat: a clinically useful measure of treatment effect. Br Med J 1995; 310: Teaching EBM: 1. Sauve S, Lee HN, Meade MO, Lang JD, Farkouh M, Cook DJ, Sackett DL. The critically appraised topic: a practical approach to learning critical appraisal. Ann Roy Coll Phys Surg Canada 1995; 28: Hatala, R, Keitz, SA, Wilson, MC, Guyatt, G. Beyond Journal Clubs: Moving Towards an Integrated Evidence-Based Medicine Curriculum. J Gen Int Med 2006; 21: EBM Teaching Tips Series There are 2 versions of each article, one for learners of the EBM principle in question and one for their teachers. The learners' version appears in CMAJ and J Gen Intern Med, and the related teachers' version is published online. (Link to the teachers' version from "Online Appendix" of the learners' version.) The online teachers' version will also give readers access to a variety of extra features, including an interactive version of the teaching article. o o o o o o o o Introduction to the series. CMAJ Aug 17;171(4): Relative risk reduction, absolute risk reduction and number needed to treat. CMAJ Aug 17;171(4): Measures of precision (confidence intervals) CMAJ Sep 2004;171: Measures of observer variability (kappa statistic) CMAJ Nov 2004;171(11): Assessing heterogeneity of primary studies in systematic reviews and whether to combine their results CMAJ Mar 2005;172(5): The effect of spectrum of disease on the performance of diagnostic tests. CMAJ Mar 2005;173(4): Making sense of diagnostic test results using likelihood ratios. J Gen Intern Med Jan;23(1): Adjusting for prognostic imbalances (confounding variables) in studies on therapy or harm. J Gen Intern Med Mar;23(3): o Understanding odds ratios and their relationship to risk ratios J Gen Intern Med May;23(5): APDIM April 2016

23 3 o o Clinical Prediction Rules (CPRs) and Estimating Pretest Probability J Gen Intern Med August;23(8): Making sense of decision analysis using a decision tree. Journal of General Internal Medicine 2009 May; 24(5): Sources of Pre-Appraised Evidence 1. Clinical Evidence, BMJ Publishing Group 2. American College of Physicians [to access ACP J. Club, High Value Care, & ACP Smart Medicine & AHFS DI Essentials] 3. Cochrane Collaboration Where Else In The World Can I Go To Learn More? Bandolier Description: Bandolier is a journal produced in Oxford, England, that focuses on current issues in Evidence-Based Medicine. CATwalk Description: Website developed by the University of Alberta Health Sciences Library to guide residents and students through the process of CAT (Critically Appraised Topic). CEBM Oxford University Description: This web site promotes evidence-based health care and provides support, resources, and information for students and clinicians. CEBM University of Toronto Description: provides information on how to practice and teach evidence based medicine. It is designed to support the fourth edition of Evidence-based Medicine: How to Practice and Teach EBM. APDIM April 2016

24 1 Glossary of Practical Epidemiology Concepts Absolute Risk Reduction (ARR) The difference of risks of an outcome between 2 experimental groups. It is the difference between the unexposed or control event rate (CER) and the treated or experimental event rate (EER). Sometimes the risk difference is between 2 experimental groups. ARR = CER - EER or ARR = EER1 - EER2 Accuracy Algorithm Attributable Risk Bias Truthfulness of results or measurements. Requires comparison to known truth. An explicit description of an ordered sequence of steps to be taken in patient care under specified circumstances. Amount or proportion of disease that is ascribed to specific exposures. Systematic error in study design which may skew the results leading to a deviation from the truth. A non-inclusive list of specific types can include: Interviewer bias error introduced by an interviewer s conscious or subconscious gathering of selective data Lead-time bias mistakenly attributing increased survival of patients to a screening intervention when longer survival is only a reflection of earlier detection in the preclinical phase of disease Recall bias error due to differences in accuracy or completeness of recall to memory of past events or experiences Referral bias the proportion of more severe or unusual cases tends to be artificially higher at tertiary care centers Selection bias an error in patient assignment between groups that permits a confounding variable to arise from the study design rather than by chance alone Volunteer bias- people who choose to enroll in clinical research may be systematically different (eg. healthier, or more motivated, ) from your patients. Workup bias when the decision to conduct the confirmatory or reference standard test is influenced by the result of the diagnostic test under study Blinded or Masked Cochrane Collaboration Blinded studies purposely deny access to information in order to keep that information from influencing some measurement, observation, or process. Double-blinded refers to the fact that neither the study subject nor the study staff is aware of which group or intervention the subject has been assigned. This international group, named after Archie Cochrane, is a unique initiative in the evaluation of healthcare interventions. The Collaboration works to prepare, disseminate, and continuously update systematic reviews of controlled trials for specific therapies. Weaving EBM into Your Clinical Teaching APDIM 2016

25 2 Co-intervention Concealment Confidence Interval Interventions other than the treatment under study. Users of articles about therapy should assess whether co-interventions were differentially applied to the treatment and control groups. A fine point associated with randomization that is very important. Ideally, you want to be reassured that the randomization schedule of patients was concealed from the clinicians who entered patients into the trial. Thus the clinician will be unaware of which treatment the next patient will receive and therefore cannot consciously - or subconsciously - distort the balance between the groups. If randomization wasn t concealed, patients with better prognoses may tend to be preferentially enrolled in the active treatment arm resulting in exaggeration of the apparent benefit of therapy (or even falsely concluding that treatment is efficacious). Clinical research provides a point estimate of effect from a sample of patients; CIs express the degree of uncertainty or imprecision on either side of the point estimate. CI represents a range of values consistent with the experimental data that provide a measure of precision or uncertainty. In other words, CIs provide us with the neighborhood within which the true value is likely to reside. CIs around study results help us make inferences about the population of all such patients. The frequently used 95% CIs is commonly defined as the range of values within which we can be 95% sure that the true value lies for the whole population of patients from whom the study patients were selected. If you were to conduct a study 100 times, the results of 95 would fall within this range. In general, 95% CIs estimate this sampling variation and are calculated by adding and subtracting 2 standard errors from the point estimate. The width of the CI is largely affected by the square root of the sample size; thus the larger the sample size the more narrow/precise is the CI. Confounder or Confounding Variable Cost Benefit Analysis Cost Effectiveness Analysis Cost Utility Analysis A factor that distorts the true relationship of the study variable of interest by virtue of also being related to the outcome of interest. Confounders are often unequally distributed among the groups being compared. Randomized studies are less likely to have their results distorted by confounders. A form of economic analysis in which the costs of medical care are compared with the economic benefits of the care, with both costs and benefits expressed in units of currency. The benefits typically include reduction in future health care costs and increased earnings due to the improved health of those receiving the care. An economic evaluation in which alternative programs, services, or interventions are compared in terms of the cost per unit of clinical effect. Some examples would include cost per life saved, or cost per unit of blood pressure lowered. A type of cost effectiveness analysis in which the outcomes are measured in terms of their social value. Cost is expressed per some incremental quality of life measure (e.g. cost per quality adjusted life year- QALY - or cost per healthy days of life gained). Weaving EBM into Your Clinical Teaching APDIM 2016

26 3 Decision Analysis Diagnosis Differential Diagnosis Economics Effectiveness Efficacy Efficiency Event Rate Evidence-Based Medicine Generalizability Gold Standard Reference Standard A systematic approach using explicit and quantitative methods to analyze decisions under conditions of uncertainty; the systematic articulation of common sense. It involves identifying all available choices and estimating the probabilities of potential outcomes for each in a series of decisions that have to be made regarding patient care. This type of analysis requires estimates of how persons value different health outcomes (patient preferences or utilities). The determination of the nature of a disease; a process of more or less accurate guessing. Commonly a possibilistic listing (noun) of potential causes of a patient s clinical problem which can be ordered (verb) for probabilistic, prognostic, or pragmatic use. Can be used actively to aid diagnostic decision-making. Explores the balance between costs and consequences of alternative actions. A measurement of benefit resulting from an intervention for a given health problem under conditions of usual practice. This form of evaluation considers both the efficacy of an intervention and its acceptance by those to whom it is offered. It helps answer does the practice do more good than harm to people to whom it is offered? A measure of benefit resulting from an intervention for a given health problem under conditions of ideal practice. It helps answer does the practice do more good than harm to people who fully comply with the recommendations? A measure of the increment in health benefits for a fixed amount of health resources. It helps answer the question is this practice worth doing compared with other things that could be done with the same resources? (see CEA, CBA, and CUA) Proportion of patients in a group in whom an event is observed. Controlled event rate (CER) and experimental event rate (EER) are used to refer to this in control and experimental groups of patients, respectively. The conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients. The practice of evidence-based medicine requires integration of individual clinical expertise and patient preferences with the best available external clinical evidence from systematic research. The extent to which the conclusions derived from a trial can be used beyond the setting of the trial and the particular people studied in the trial. Are the results applicable to the full population of all patients with this condition? {see inference which deals with individualizing evidence to specific patients} An established method, or a widely accepted method, for determining a diagnosis. It provides a standard to which a new screening or diagnostic test can be compared. New method is most often a single intervention, however, it can also include: follow-up of patients to observe the evolution of their condition, consensus of expert panel of clinicians, or a combination of methods. Most importantly in articles about diagnostic tests, the gold Weaving EBM into Your Clinical Teaching APDIM 2016

27 4 standard must be explicitly acknowledged and applied independently in a blinded fashion. Health Health Care Costs Health Outcome A state of optimal physical, mental, and social well being; not merely the absence of disease and infirmity (World Health Organization). These concern the use of health care resources (direct and indirect) and the inability to use the same resources for other worthwhile purposes (opportunity costs). All possible changes in health status that may occur in an individual or in a defined population or that may be associated with exposure to an intervention. Inception Cohort Incidence Inference A designated group of persons assembled at a common time early in the development of a specific clinical disorder and who are followed thereafter. In assessing articles about prognosis it is critical that the inception cohort is well described in order to permit assessment of the homogeneity of the cohort. Number of new cases of disease occurring during a specified period of time; expressed as a percentage of the number of people at risk. To arrive at a conclusion. The act of taking information from published experience and individualizing to specific patients. The hierarchy and quality of available evidence significantly influence the strength of inference. You should reflect on your level of dogmatism about applying a study s results after assessing the validity of the evidence. In other words, identify where you are on the spectrum from toothless dogmatism to rabid dogmatism. Intention-to-Treat Analysis Kappa Statistic Analyzing patient outcomes based on which group they were randomized into regardless of whether they actually received the planned intervention. This analysis preserves the power of randomization, thus maintaining that important unknown factors that influence outcome are likely to be distributed equally in each comparison group. A measure of agreement between observers that is beyond any agreement expected to occur by chance alone. K > 0.8 is excellent; K < 0.4 is poor. Likelihood Ratio A ratio of likelihoods (or probabilities) for a given test result. The first is the probability that a given test result occurs among people with disease. The second is the probability that the same test result occurs among people without disease. The ratio of these 2 probabilities (or likelihoods) is the LR. It measures the power of a test to change the pre-test into the posttest probability of a disease being present. This ratio expresses the likelihood that a given test result would be expected to occur in patients with the target disorder compared to the likelihood of that same result in patients without that disorder. The LR for a given test result compares the likelihood of that result occurring in patients with disease to the likelihood of that result in patients without Weaving EBM into Your Clinical Teaching APDIM 2016

28 5 disease. Expressed in other words, LRs contrast proportions of patients with and without disease who have a given test result. Matching Median Survival Meta-Analysis Number Needed to Harm (NNH) A deliberate process to make the study group and comparison group comparable with respect to factors (or confounders) that are extraneous to the purpose of the investigation but which might interfere with the interpretation of the studies findings. For example in case control studies, individual cases may be matched with specific controls on the basis of comparable age, gender, and/or other clinical features. Length of time that one-half of the study population survives. A systematic review which uses quantitative tools to summarize the results. The number of patients who would need to be treated over a specific period of time before one adverse side-effect of the treatment will occur. It is the inverse of the absolute risk increase. NNH= 1/ARI Number Needed to Treat (NNT) The number of patients who need to be treated over a specific period of time to prevent one bad outcome. When discussing NNTs, it is important to specify the treatment, its duration, and the bad outcome being prevented. It is the inverse of the absolute risk reduction (ARR). NNT = 1/ARR Odds A ratio of probability of occurrence to non-occurrence of an event Odds = probability/1-probability Odds Ratio A ratio of odds that s most often used in case-control study designs to describe the degree of association between an exposure and the outcome of interest (e.g. the odds of exposure in cases compared to the odds of exposure in the controls). While this retrospective study design doesn t permit true calculation of the rates of new outcome events, when the outcome of interest is infrequent (<20%) the odds ratio very closely approximates the relative risk. ***BUT, it must be recalled that this approximation comes from a weaker study design than one that can measure risk so temper your dogmatism*** ORs can also be calculated in prospective studies by describing the odds that a patient in the exposed or intervention group suffers an adverse event relative to a control patient. Outcomes P-value All possible changes in health status that may occur in following subjects or that may stem from exposure to a causal factor or to a therapeutic intervention. From hypothesis testing wherein the probability of the particular result occurring by chance alone is calculated. The smaller the p-value, the less likely the difference occurred by chance. {note that increasingly, studies Weaving EBM into Your Clinical Teaching APDIM 2016

29 6 are reporting results with confidence intervals, which provide much more helpful information to the clinician about the clinical significance of the results and their precision}. Power Practice Guidelines Precision Predictive Value Prevalence Prognosis Quality Adjusted Life Year (QALY) Quality of Care Randomization Receiver Operator Characteristic Curve (R.O.C. Curve) Relative Risk Ability to detect a difference between two experimental groups if one in fact exists. Systematically developed statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstances. They are a set of statements, directions or principles presenting current clinical rules or policy concerning proper indications for performing a procedure or treatment or for the proper management of specific clinical problems. Guidelines may be developed by a wide range of authors including professional societies, governmental agencies, health care institutions, or by convening expert panels. Synonyms include practice parameters or practice policies. A measure of reproducibility. Positive Predictive Value - proportion of people with a positive test who have disease. Negative Predictive Value - proportion of people with a negative test who are free of disease. Proportion of persons affected with a particular disease at a specified time. Prevalence rates obtained from high quality studies can inform clinician s efforts to set anchoring pretest probabilities for their patients. The possible outcomes of a disease and the frequency with which they can be expected to occur. A unit of measure for survival that accounts for the effects of morbidity on quality of life. For example if a patient lives for ten years and his quality of life is decreased by 50% because of chronic lung disease, his survival would be equivalent to five quality adjusted life years. A level of performance or accomplishment that characterizes the health care provided. Allocation of individuals to groups by a formal chance process such that each patient has an independent, equal chance of selection for the intervention group. It is usually facilitated with the aid of a table of random numbers. A visible representation of a series of likelihood ratios. It graphs out the TPR (i.e. sensitivity) versus the FPR (i.e. 1-specificity) for a range of test results. The single test result that optimizes sensitivity and specificity is found at the point furthest to the northwest. An R.O.C. curve for a perfect test has an area under the curve = 1.0 while a test that performs no better than by chance has an area under the curve of only 0.5. Risk of an adverse outcome in the intervention group compared to the risk in the control group. Also known as Risk Ratio, which is the ratio of risk in the experimental group (EER) to the risk found in the control group (CER). It is similarly used to express the ratio of risk for disease or death among an exposed population to the risk among the unexposed cohort. Risk Ratio is used in randomized controlled trials and cohort studies. Weaving EBM into Your Clinical Teaching APDIM 2016

30 7 RR = EER / CER Relative Risk Reduction (RRR) A percent reduction in an outcome event in the experimental group as compared to the control group. It is the complement of RR, or the proportion of risk that s removed by the intervention (analogous to a tag announcing a sale i.e. 20% off). RRR = 1 Relative Risk RRR = CER EER / CER X 100 {Or obviously RRR = ARR / CER} Reliability Risk Aversion Sensitivity SnNout Sensitivity Analysis Refers to consistency or reproducibility of data; repeatability. To avoid taking a chance on winning or losing a future outcome, a patient will accept a present outcome that is valued less then the uncertain future outcome. The proportion of people with disease who have a positive test. It is the rate of Positivity In Disease ( PID ). When a test with a high sensitivity is negative, it effectively rules out the diagnosis of disease. Any test of the stability of the conclusions of the health care evaluation over a range of probability estimates, value judgments, and assumptions about the structure of the decisions to be made. This involves the repeated evaluation of the decision model in which one or more of the parameters of interest is varied. Sensitivity Analysis is the systematic exploration of the impact of uncertainty in the evidence used upon the stability of the analytic conclusions. It is the shaking of the decision tree that was constructed. Sensitivity Analysis helps clinicians interpret the robustness of a study s conclusions. Specificity SpPin Standards The proportion of people without disease who have a negative test. It is the rate of Negativity In Health ( NIH ). When a test is highly specific, a positive result can rule in the diagnosis. Authoritative statements of minimal levels of acceptable performance or results, excellent levels of performance or results, or the range of acceptable performance or results. Study Designs 1. Case Series - A collection or a report of the series of patients with an outcome of interest. No control group is involved. 2. Case Control Study - Identifies patients who have an outcome of interest (cases) and control patients without the same outcome. It then requires an investigation into whether or not the cases and controls had been previously exposed to a variable of interest. Advantages include that it is relatively quick and inexpensive requiring fewer subjects than other study designs. It is often times Weaving EBM into Your Clinical Teaching APDIM 2016

31 8 the only feasible method for investigating very rare disorders or when a long lag time exists between an exposure of interest and development of the outcome/disease of interest. Its disadvantages include reliance on recall, unknown confounding variables, and difficulty selecting appropriate control groups. 3. Crossover Design A method of comparing 2 or more treatments or interventions in which all subjects are switched to the alternate treatment after completion of the first treatment. Typically allocation to the first treatment is by a random process. Since all subjects serve as their own controls, error variance is reduced. 4. Cross-Sectional Survey - The observation of a defined population at a single point in time or during a specific time interval. Exposure and outcome are determined simultaneously. 5. Cohort Study - Involves identification of two groups (cohorts) of patients (one received the exposure of interest and one did not) and then following these cohorts forward in time in order to detect the relative rates of outcome of interest in each group. Advantages: can establish clear temporal relationships and is administratively easier and less expensive than a randomized controlled trial. Disadvantages: control/unexposed groups may be difficult to identify, exposure to a variable may be linked to a hidden confounding variable, blinding is often not possible, and randomization is not present. For relatively rare diseases of interest, cohort studies require huge sample sizes and long f/u. 6. N-of-1 Trial When an individual patient undergoes pairs of treatment periods organized so that one period involves use of the experimental treatment and the other involves use of a placebo or alternate therapy. Ideally the patient and physician are blinded, and outcomes are measured. Treatment periods are replicated until patient and clinician are convinced that the treatments are definitely different or definitely not different. 7. Randomized Controlled Trial - A group of patients is randomized into an experimental group and into a controlled group. These groups are then followed up through various outcomes of interest. It is the ultimate standard by which new therapeutic maneuvers should be judged. Randomization provides unbiased distribution of unknown confounding variables into each group. Disadvantages include volunteer bias, significant expense, and sometimes they are ethically problematic. 8. Meta-Analysis - A systematic review which uses quantitative methods to combine the results of studies into a pooled summary. Substitute or Surrogate Endpoints Refer to study outcomes that are not immediately significant in clinical patient care. Substitute endpoints may include rates of biochemical changes (e.g., cholesterol, HbA1C) while clinically significant endpoints are more clearly tied to events that patients and their doctors care about most (e.g., stroke, renal failure, death). Weaving EBM into Your Clinical Teaching APDIM 2016

32 9 Threshold Analysis At what value of the question probabilities a decision-maker would consider the currently favored strategy no better than its next best alternative. Utility Validity Values Refers to patient preferences that are measured with techniques consistent with modern utility theory. Patient preferences refer to the degrees of subjective satisfaction, distress, or desirability that patients or potential patients associate with a particular health outcome. Utility theory is based on specific axioms that describe how a rational decision-maker ought to make a decision when the outcomes of that decision are uncertain. Commonly used measures of utility include the standard gamble or time trade-off techniques. Truthfulness or believability of study conclusions or the extent to which a test actually measures what it is supposed to measure or accomplishes what it is supposed to accomplish. Simply put, Does the data really mean what we think it does? or Can we believe the results? The basis for individual personal preferences concerning different outcomes. Weaving EBM into Your Clinical Teaching APDIM 2016