Since the 1990s, a wave of evidence-based medicine has swept the world. The famous British medical journal The Lancet has compared evidence-based medicine to the Human Genome Project of clinical science. Just like the impact of the discovery of antibiotics on medicine, evidence-based medicine is revolutionizing the ancient paradigm of medical practice. Evidence-Based Medicine (EBM) is medicine that follows scientific evidence. It emphasizes the integration of the best clinical research evidence with clinical practice (clinical experience, clinical decision making) and patient values (concerns, expectations, needs). The intent is to use the most current and robust scientific research information to guide clinicians to the most appropriate diagnostic methods, the most accurate prognostic estimates, and the safest and most effective treatments for their patients.EBM emphasizes that physicians should carefully and thoughtfully apply the best evidence currently available to the decisions they make in the delivery of health services to each patient. So that the care we provide is based on the evidence that is currently available. Traditional medicine is based on empirical medicine, i.e., dealing with patients based on the physician’s empirical intuition or pathophysiology, etc., and reading textbooks to consult specialists or reading journals based on experience and biological knowledge. The modern medical model is to emphasize evidence-based medicine along with empirical medicine, in which physicians who have mastered clinical epidemiological theories and methods and also have some clinical experience, based on careful history taking and physical examination, conduct effective literature searches according to the patient’s condition and requirements, apply formal methods of evaluating clinical literature to discover the most relevant and correct information, apply the literature, i.e., evidence, in the most effective way, and solve clinical problems based on evidence Solve clinical problems, develop preventive and therapeutic measures for diseases, and achieve the best treatment results. Therefore, in the academic decision-making, the best treatment is achieved. Therefore, in the process of evidence-based medical practice, physicians are the key, research evidence is the core, clinical experience is the substrate, and patients are the foundation. Evidence-based clinical practice has changed the thinking pattern of physicians. Evidence-based medicine has brought significant changes to the clinical practice, teaching and research of physicians: ① Evidence-based clinical practice has changed people’s attitude towards cognition, the traditional academic authority has been questioned, and there is a shift from physician-centered (decision making is made by physicians) and disease-centered (treatment is mainly based on the pathophysiology of the disease) to patient-centered, focusing on patients’ subjective feelings and satisfaction. Instead of being embarrassed by “not knowing”, physicians realize that lack of knowledge is a motivation to continue learning. Evidence-based clinical practice is an exciting way of practice that teaches self-directed, problem-based learning and leads to continuous exploration and lifelong learning. Ultimately, they become excellent physicians who are constantly seeking new ideas, are open to learning, and are close to their patients. ③ Patients and physicians are partners on an equal footing, and it is the physician’s responsibility to provide as comprehensive evidence as possible, to communicate fully with the patient, and to assist the patient rather than make decisions for the patient. Section II Evidence Synthesis-Systematic Evaluation and Mata Analysis Literature reviews are often an important way to obtain research advances and up-to-date information in the specialty. However, traditional narrative literature reviews often fail to provide truly scientific and reliable medical information because of methodological limitations. In recent years, with the increasing improvement of methodology. The systematic evaluation method is used to systematically search and critically evaluate the literature. I. Systematic evaluation Systematic evaluation is a rigorous method of evaluating the literature, which adopts the principles and methods of clinical epidemiology to reduce bias and random error for a specific clinical problem, systematically and comprehensively collects all published or unpublished clinical research results worldwide, screens out the literature that meets quality standards, conducts qualitative analysis and quantitative synthesis, and obtains more reliable conclusions. Both traditional narrative literature reviews and systematic evaluations are analyses and summaries of clinical research literature. However and, there is a difference between the two, the main disadvantage of literature review compared to systematic evaluation is that the former is highly subjective and prone to bias and error. The difference between literature review and systematic evaluation II. Meta-analysis A large number of clinical studies are currently available, and the number of sample cases included in the study is too small due to the conditions. This leads to low test efficacy, and some studies of the same type may occur. However, inconsistent results were obtained. Meta-analysis can be considered when analyzing and evaluating the results of these inconsistent studies to improve the test efficacy through quantitative pooled analysis. Thus, it is beneficial to discover the best evidence for evidence-based medical practice. Meta-analysis is a quantitative synthesis of multiple medical studies with the same purpose and similar nature, including a series of processes such as asking research questions, developing inclusion and exclusion criteria, searching for relevant studies, summarizing basic information, synthesizing and reporting results, etc. Meta-analysis is sometimes also called meta-analysis. Broadly speaking, people often refer to Meta-analysis as systematic evaluation as well. In fact, there is a difference between the two. Meta-analysis is a quantitative synthesis of the results of multiple independent, synthesizable clinical studies using statistical analysis. In contrast, systematic evaluation does not necessarily imply quantitative synthesis of the results of related studies; it can be either a qualitative systematic evaluation or a quantitative systematic evaluation that includes Meta-analysis. Systematic reviews can be divided into two types:qualitative systematic reviews and quantitative systematic reviews, the latter of which is Meta-analysis. The difference between systematic evaluation, Meta-analysis, and traditional review Section 3: Sources and classification of evidence in evidence-based medicine Evidence-based practice emphasizes on the best available evidence, so it is crucial to obtain relevant evidence in a comprehensive and systematic manner. 1. Classification and sources of evidence 1. Original research evidence and sources: It refers to the first-hand data of single studies on etiology, diagnosis, prevention, treatment, rehabilitation and prognosis conducted directly in patients, and the conclusions obtained after statistical processing and analysis and summarization, mainly including single randomized controlled trials, crossover trials, cohort studies, case-control studies, non-randomized concurrent controlled trials and narrative studies, etc. Commonly used sources of primary research evidence include the following categories. (1) MEDLINE database established by the US National Library of Medicine. (2) European EMBASE database. (3) Chinese Biomedical Literature Database (CBM). (4)China Evidence Based Medicine/Cochrane Center Database (CEBM/CCD). 2. Secondary research evidence and sources:It is the conclusion obtained by collecting all the original research evidence of studying a certain issue as comprehensively as possible, after rigorous evaluation, integration and processing, and analysis and summarization, and is the higher quality evidence obtained after reprocessing multiple original research evidence. It mainly includes systematic reviews, health technology assessments, and clinical practice guidelines. Commonly used sources of secondary research evidence include the following categories. (1) Databases: Cochrane Library; Evidence-Based Medical Reviews (EBMR); Center for Evaluation and Dissemination Database (CRDD); Clinical Evidence (CE); National Institutes of Health Health Health Technology Assessment and Directions Release Database (NIHCS/TAS). (2) Journals: Journal of Evidence-Based Medicine; Journal Club of the American College of Physicians; Bandolier; Journal of Evidence-Based Nursing; Journal of Evidence-Based Health Care and Public Health; Chinese Journal of Evidence-Based Medicine. (3) Guidelines: National Guidelines Collection (NGC); Guidelines. Second, retrieval of evidence including computer search and manual search. 1.Evidence evaluation and grading:The retrieved research evidence often needs to be critically evaluated using the criteria of clinical epidemiology and evidence-based medicine quality evaluation when applied to solve specific clinical problems. RCT is the best research method to assess the effects of interventions [treatment, prevention). In the critical evaluation of research evidence of intervention effects, the quality of clinical research evidence is generally classified into 6 levels according to different study types, with decreasing quality from level I to level VI. 2. Evaluation of evidence:Regardless of which type of clinical research evidence is evaluated, its value should be considered comprehensively at three levels. ① evaluation of authenticity; ② evaluation of clinical significance; ③ evaluation of clinical applicability. Section IV Clinical Practice Guidelines Clinical practice guidelines (CPGs) refer to guidelines that are systematically developed to help clinicians and patients make appropriate management for a specific clinical situation, and are a bridge between evidence and clinical practice, and reflect the current state of the best clinical evidence at the time. Clinical practice guidelines are developed to regulate medical practice. Drugs and medical technologies are applied appropriately to avoid over-application, use and under-application, to avoid harming patients and to achieve optimal medical outcomes. However, a recent study found that although the recommendations in the guidelines are increasing year by year, most of them do not have clear evidence. For this reason appropriateness criteria, in this case domestic and foreign on the basis of guidelines, successively developed appropriateness criteria and medical quality standards, as well as expert consensus and scientific statements and other documents. There is now sufficient evidence-based medical evidence to confirm that guidelines can improve the prognosis of patients. When using guidelines, their authenticity and reliability should be evaluated, and the main points of evaluation are: (1) whether the guideline developers have collected the most recent, including relevant evidence within the past 12 months, and have conducted a comprehensive review of the literature. (ii) Whether the supporting evidence for each recommendation was marked with a grade and attribution. The main issues at present focus on the collection, evaluation and synthesis of evidence, and how closely to integrate the recommendations with their relevant evidence. First of all, it should be clear that clinical practice guidelines are only reference documents for clinicians to deal with clinical problems, not regulations. They should be avoided to be used in a mandatory, blind and dogmatic manner regardless of the specific situation of the patient. Guidelines are general guidelines for most (or typical) patients or most situations, and cannot include or solve all complex and specific clinical problems of every patient. Second, the clinical application of guidelines 1, understand the method of guideline development. A truly evidence-based guideline is more reliable than a non-evidence-based guideline. 2.Read the explanation of the level of evidence against the strength of the recommendation table and understand its meaning in order to judge the reliability of the recommendation. 3. Determine the clinical application based on the strength of the recommendation. If a therapy is recommended at level A, it can be used basically without contraindications; at level B, it can be used but it should be noted that the evidence is not sufficient; at level C, it suggests that the evidence is even more lacking. The general principle is that if there is no good reason, the opinion of the guidelines should be referred to, because even the B-level and C-level recommendations are the result of extensive review of the literature and multiple discussions among multiple people, and their reference value is greater than the limited personal experience. Chapter 27: Application of evidence-based medicine in dermatologic care How to weigh the pros and cons of therapeutic measures and how to obtain the most reliable evidence to guide us in providing the best treatment for specific patients is at the heart of evidence-based care. The questions that should be answered as a matter of priority can be summarized into five steps, each of which has a rich connotation and a scientific approach, according to the methodology of evidence-based practice abroad, and they become a complete system, namely the “five steps” of evidence-based practice. Ask a clear, answerable clinical question. Evidence-based medicine cannot attempt to solve all clinical questions at once. For example, how do you choose a treatment for your patient that has more benefits than harms and definite efficacy? Examples of treatment questions related to dermatology are listed below. 1. Pemphigus: ①What is the best hormonal agent to use for the patient you admit with common pemphigus? ② What immunosuppressive drugs are most effective for your patient with aspergillosis? 2. Nail fungus: A patient with onychomycosis (distal lateral subxiphoid nail fungus) was seen in the outpatient clinic and was faced with the clinical treatment question: Which of terbinafine, itraconazole, fluconazole, and ashwagandha would be most effective in treating this patient with onychomycosis? The first step is to identify the relevant “key words” and apply the electronic search system and journal search system to retrieve the relevant literature to find out the information that is closely related to the clinical problem and use it for analysis and evaluation. Third, rigorous evaluation of evidence The collected research evidence is strictly evaluated for its authenticity, reliability and applicability by applying the criteria of clinical epidemiology and evidence-based medical quality evaluation. If there are multiple pieces of qualified literature collected, systematic evaluation and Meta-analysis are available so that the evaluation conclusions are more reliable. The quality of clinical studies can be classified into 5 levels from high to low according to their scientificity and reliability: ① large-sample multicenter RCTs or systematic evaluation and/or meta-analysis done by collecting these RCTs; ② single large-sample RCTs; ③ clinical trials with control groups; ④ series of studies without control groups; ⑤ expert opinions, descriptive studies and case reports. The best results are applied to clinical decision-making. The best evidence is obtained from the critically evaluated literature. It will be used for patients and serve the clinic according to the principle of individualization. V. Summarize and improve Through the clinical practice of evidence-based medicine, summarize the successful and unsuccessful experiences and lessons learned, benefit from them, and improve the clinical level.