EVIDENCE-BASED PATHOLOGY (EBP)
Overview
Evidence-Based Pathology (EBP) is an international movement aimed at promoting the understanding and use of evidence-based principles in Cellular Pathology (Histopathology). Through research publications, guideline production, education, and promotion, EBP hopes to improve patient care by strengthening the rationale behind the clinical practice of Cellular Pathology.
What is Cellular Pathology?
Cellular Pathology - also known as histopathology, surgical pathology, or anatomic pathology - is a laboratory-based medical specialty that focuses on making diagnoses by looking at patient tissue samples using a microscope. These samples are usually biopsies (which some might call 'tests') or tissues and organs removed during an operation. Cellular Pathologists are medical doctors involved in making diagnoses (or confirming diagnoses suspected clinically or from X-rays and scans) and, along with radiologists, are an important part of the diagnostic team caring for patients.
What is Evidence-Based Health Care?
One definition of evidence-based practice is clinical care that integrates the best available medical research with clinical expertise and patient values. Clinical care includes making a diagnosis as well as a treatment plan. As pathologists, this means using the best available evidence, along with our clinical experience and understanding of patient wishes, when making diagnoses and prognoses for our patients.
Evidence-Based Principles
'Best evidence' is hinting at the idea that some evidence is of higher quality than others, with systematic reviews and randomised controlled trials being the gold standards (having the least bias), followed by less well controlled trials such as cohort or case-control studies, then basic laboratory research (because this does not involve patients). See the 'Levels of Evidence in Tumour Pathology' below. Of course, the best available may not be the ideal or gold standard. It's also worth bearing in mind that this 'hierarchy of evidence' does not imply any particular type of evidence is intrinsically unworthy or should be ignored, but that we can have more confidence in some types of evidence for predicting what will help a patient in a clinical, real world setting.
How is NDS involved?
The EBP work in NDS is led by Richard Colling and along with other Oxford researchers, we are contributing to primary studies, systematic reviews, and gudeline production. The recently launched WCT EVI MAP project is now running in collaboration with IARC, along side the IC3R (WHO) EPB project. NDS projects involve collaboration with pathologists in the Department of Cellular Pathology at Oxford University Hospitals NHS Foundation Trust as well as academics from other University departments, including the Centre for Evidence-Based Medicine (Nuffield Department of Primary Care Health Sciences). Some of our collaborators and a few example projects are listed on the left hand side.
Levels of Evidence in Tumour Pathology
WHO/IARC have propsed a new Hierarchy of Research Evidence for Tumor Pathology. This new hierarchy is dedicated to, and tailored for, tumour pathology, with the main focus being on the WHO Classification of Tumours (WCT 'blue book series'). The hierarchy is not meant to replace other similar levels used in EBM, but to compliment these for pathologists. The hierarchy is arranged at the top level to map to the various sections of the WCT, i.e., matching chapter subheadings as far as possible. The various subheadings are grouped into similar research topics of interest, such as tumor characteristics, prognostics etc. Example subject-based related questions that pathologists may ask are then given below. The levels are presented in order of robustness - i.e., Level P1 having the lowest risk of bias, Level P5 the greatest. Each level for each subsection contains the list of evidence-types that rank at that level (in alphabetical order, no intra-level ranking implied). Most types of evidence can be thought of as ‘studies’, but not all. Studies of rare tumors (defined here as those with an incidence of less than 1 per million population per annum) are automatically upgraded one level. This would include case reports which may be the only unique diagnosis of its type in the literature. Large sample size Level P2 studies should be upgraded to Level P1.
The open access, peer-reviewed paper (pre-proof) explaining the hierarchy and the glossary of definitions for study types is available here.
*Systematic reviews predominantly including Level P2 studies. Systematic reviews of predominantly Level P3-5 studies are placed in Level P2. Rapid reviews are placed in Level P2.