levels of evidence study designs

when apprasing

appraise the strength (hierarchy) and quality/applicability

case report/case series

•Research Type: Primary research (unfiltered) •Evidence Level: 4 (low) •Definition: case reports are detailed descriptions of individual cases which may focus on a disease, symptoms, intervention, outcome, adverse event, or unusual occurrence. Case reports are NOT based on systematic studies and their conclusions may not be generalizable to a wider population. They are considered the lowest level of evidence, but can help identify new diseases, potential treatments, side effects, or areas for further research. A case series is a group of case reports involving patients who were given similar treatment •**Avoid using case reports or case series to answer your clinical questions

level 2

cohort studies; prospective

secondary (filtered) sources

essential to EBP; combine individual primary sources to synthesize evidence for clinical use ex: CATs, meta-analyses, systematic reviews

prospective studies

examine the current pathology and follows the individuals with the pathology over a period of time or examine a group of individuals and wait until patient presents with a pathology to predict factors that contributed to pathology

primary (unfiltered sources)

helpful when you cannot find secondary filtered sources to answer your question ex: case series/reports, controlled studies, cohort studies, RCTs

probability of bias

hierarchies rank studies according to the probability of bias; less at top more at bottom

level 5

narrative reviews, expert opinions, editorials

meta-analysis

statistical methods are employed to quantitatively pool the results of the studies within a systematic review

higher

studies in which randomization occurs represents a ___ level of evidence than those in which the subject selection is NOT random

retrospective studies

studies that examine data that has already been collected (medical records, PPE, etc) or studies for which data on subjects who already have a pathology (ankle sprain) are compared with a control group that does not have the pathology

highest level

the goal is to find the ____ of evidence to answer clinical questions

systematic review

unable to provide employ a statistical method to pool the results of the included studies due to differences in outcomes (studies to different to combine)

compilation studies

when there is enough information and data on a specific topic; aggregaing multiple studies to answera clinical question that may not be answerable with a single study ex: meta analyses, systematic reviews

observational study designs

•A type of study in which individuals are observed or certain outcomes are measured •Researcher observes the effect of a risk factor, diagnostic test, treatment or other intervention •No attempt is made to affect the outcome (e.g. no treatment is given)

cross-sectional studies

•Research Type: Primary research (unfiltered) •Evidence Level: 4 (moderate) •Definition: a type of research design in which you collect data from many individuals at a single point in time. Cross-sectional studies investigate the prevalence of particular health outcomes and the exposure or risk factors present in a population at particular point in time. Data can bed used to consider the association between outcomes and exposures. •**Use these to support your diagnosis questions

cohort study designs

•Research type: Primary (unfiltered) source •Evidence level: •Prospective cohort study=level 2 (moderate) •Retrospective cohort study=level 3 (moderate) •Definition: used to investigate links between suspected risk factors and health outcomes. By selecting participants based on their exposure status, cohort studies compare health outcomes between exposed and unexposed groups. Preferred study design for investigating causes of disease because it would be unethical to intentionally expose participants to a potential risk factor •Retrospective vs. prospective cohort studies •**Use these to support your prognosis and harm/etiology questions

randomized controlled trials

•Research type: Primary (unfiltered) source •Evidence level: 1a (High) •Definition: experiments which explore the effectiveness of an intervention which is administered to real patients. Patients are randomly assigned to either an intervention group or the control group. Data is then compared to determine if there is a statistically significant difference between the outcome of each group. Double-blind RCTs are the gold standard for determining cause- and effect between an intervention and an outcome. •**Use these to support your therapy, prognosis, harm/etiology, and prevention questions

case-control studies

•Research type: primary (unfiltered source) •Evidence level: level 3 (moderate) •Definition: compare patients who already have a specific outcome with people who don't. In case-control studies, the researcher looks back to identify factors that might be associated with the condition, often using past medical records and patient recall. These studies are observational because no intervention is administered to the participants •**Use these to support your prognosis and harm/etiology questions

non-randomized controllled trials

•Research type: primary (unfiltered) source •Evidence level: moderate •Definition: experiments which explore the effectiveness of an intervention which is administered to real patients. In a non-randomized trial, the researchers may select which treatment group participants are assigned to, or may allow participants to select a treatment group. This can lead to selection and allocation bias which may influence the results of the study. •**Use these to support your therapy, prognosis, harm/etiology, and prevention questions

qualitative studies

•Research type: primary (unfiltered) source •Evidence: level 4 (low) •Aim to develop concepts to help us understand social phenomena •Provide emphasis to the meanings, experiences, and views of the participants • No quantitative data collected •Qualitative, narrative descriptions provided based on open-ended questions, interviews, and observations. •Primary objective: to obtain a more in-depth understanding of the individual's perspective, in their own words, within a certain context

meta-analysis

•Research type: synthesis (secondary, filtered source) •Evidence level: 1a (very high) •Definition: collects data from a number of primary studies and analyzes the data as if it were one large study. Because of their large data pool, meta-analyses provide a higher degree of statistical validity which makes their conclusions more reliable than individual study results •**This type of study design will support all clinical decisions

systematic reviews

•Research type: synthesis (secondary, filtered source) •Evidence level: Level 1a (very high) •Definition: attempts to identify, appraise, and synthesize all relevant research to answer a clearly focused review question. Researchers must use explicit and reproducible methods aimed at minimizing bias in the review process, in order to produce more reliable findings •**This type of study design will support all clinical decisions

critically appraised topic

•Research type: synthesis (secondary, filtered source) •Evidence: High •Definition: a short summary of research evidence organized around a clinical question, aimed at providing both a critique of the search and a statement of the clinical relevance of results •**This type of study design will support all clinical decisions

clincial practice guidelines

•Research type: synthesis (secondary, filtered source) •Evidence: High •Definition: recommendations on how to diagnose and treat a medical condition. Mean tot help ensure that patients receive appropriate treatment and care. Guidelines summarize the current medical knowledge, weight the benefits and harms of diagnostic procedures and treatments, and give specific recommendations about the scientific evidence supporting those recommendations •**This type of study design will support all clinical decisions

experimental designs

•Studies in which the researchers introduce an intervention and study the effects •Always prospective in nature •Involve the manipulation of subjects to determine causal relationships •Adhere to strict protocols (difficult to recruit and retain subjects) •Expensive and time-consuming •Some of the highest quality evidence available

descriptive study designs

•Type of research design that aims to obtain information to systematically describe a phenomenon, situation, or population •Answers the what, when, where, and how questions rather than the why •Provides a base for further research (often experimental in nature) •Unlike experimental research, the researcher does NOT control or manipulate any variables •Rather, the variables are only identified, observed, and measured •Includes the following study designs: •Case Report (Case Study) •Case Series •Cross Sectional Studies (Surveys/Questionnaires)

evaluating study designs

•Used to determine the existence and strength of a possible association between an intervention and outcome •Focus is to reach a conclusion based on comparisons of groups and findings •Divided into two categories: •Observational Study Designs •Cohort Studies (can be retrospective OR prospective) •Case-Control Studies •Experimental Study Designs •RCT's •Nonrandomized experimental designs •Systematic Reviews •Meta-Analyses •CATs •Clinical Practice Guidelines

controlled studies

carry a higher level of evidence than those in which control groups are not used

level 3

case control studies; retrospective

level 4

case reports or case series

level of evidence 1

clinical practice guidelines, meta-analysis, systematic reviews, randimozed controlled trials