LO 3 Flashcards
What is important to understand about scientific evidence?
- It is a product of a well-designed and well- controlled research investigations that minimize sources of bias.
- A single research study does NOT constitute “ the evidence”
- EBDM challenge: when there is only one research study available on a particular topic
- Caution should be taken in relying on the study because it can be contradicted later by another study
The two types of evidence-based sources are ________ and _________
- Primary
- Secondary
Describe primary sources of evidence
- Original research publications
- Not filtered, not synthesized
- Consists of qualitative and quantitative research
Describe secondary sources of evidence
- include reviews of already conducted research
- Filtered and synthesized
- Systematic Review & Meta-Analysis
What is the importance of appropriate study design
- Integral to answering clinical questions
- Influences the level of evidence
- Influences confidence in clinical outcomes
What should be considered when looking for evidence
- Appropriateness of research methodology
- Strength of experimental design
- Control of potential bias
What is quantitative research?
- “relating to, measuring, or measured by the quantity of something rather than its quality”
- Looks at numbers of things (quantifiable data)
- Based on measurements
- Typically uses statistical analysis
What is qualitative research
- “relating to, measuring, or measured by the quality of something”
- Describes the quality of something in size, appearance or value
- In research, describes results with narratives rather than statistical analysis
Define observational research
Researchers OBSERVE study subjects
Define interventional research
- Researchers control the intervention in the study.
- Treatment may be given
Describe In Vivo research
- On live subjects/ living organism (laboratory animal, human being)
- Mimics real-life situations
- More easily generalizable to real life subjects
Describe In Vitro research
- In glass(dish or test tube)
- Only in laboratory
List the options for quantitative observational studies
- Cross-sectional study
- Case-control study*
- Cohort study
- Case report*
- Case series*
List the options for quantitative interventional (experimental) studies
- Noncontrolled trials
- Randomized controlled trials
- Controlled clinical trials
*Can be prospective or retrospective
List the options for qualitative studies
- Case report*
- Case series*
- Case Control study*
What are the 5 categories of observational studies
- Cross-sectional study
- Case control study - quantitative and qualitative
- Cohort study
- Case report - quantitative and qualitative
- Case series - quantitative and qualitative
Describe cross sectional studies
- Attempts to gather information about a population at a point in time (like a camera snap shot)
- Success is dependent upon control during the study
- What information is gathered? - Exposure and disease status
- Can be a population survey, clinical study, or record review assessing characteristics of a population
- Study subjects are NOT followed for any period of time, there is no intervention or experimentation - Information is collected just once
- Information that is gathered relates to the exposure of the population to the potential of a disease and disease status
- Cross sectional studies are appropriate to use is the question relates to the INCIDENCE or PREVALENCE of a disease
Define incidence, prevalence, and occurrence of disease
- INCIDENCE – occurrence, rate or frequency of a disease
- PREVALENCE - measurement of all individuals affected by the disease at a particular time – how widespread a disease is
- OCCURRENCE – the frequency of something happening
What do you need to keep in mind when recruiting for a cross-sectional study?
- Careful selection of sample is critical (representative with appropriate criteria)
- Variable response rates introduce bias
- Who were the respondents?
- Did they exhibit the trait in question?
- What about the individuals who did not respond?
What are the strengths and weaknesses of a cross-sectional study?
Strengths
1. Direct approach
Weaknesses
1. Recruitment bias (is the sample representative?)
2. Inaccuracies in reporting - Projection of positive image, misunderstanding of question; What is the reliability of responses? This supports validity
3. Examiners may introduce bias - Observer error or correlation of appearance to wear rather than non-traumatic morphologic variation
Describe a case control study
- Includes cases and controls to answer a question (no intervention)
- Case group = diseased individuals
- Control group = healthy individuals
- Retrospective
What are case-control studies used for?
- Elucidating potential associations
- Need an answer quickly
- Rare conditions/diseases
*unlikely to establish cause and effect
What are the strengths and weaknesses of a case-control study?
Strengths
1. Rare disease investigation
2. ie. intercranial meningioma (cancer of brain tissue)
3. To conduct a higher level study, it would be unethical and require a long period of time to study causes in a prospective study
Weaknesses
1. Recall bias
2. Clients with a disease or condition are more likely to recall or remember events that they feel may have been associated with their condition
Describe cohort studies
- Group of individuals with similar baseline characteristics is observed over time
- Prospective
- Commonality = behavior, condition, environmental exposure
- Is the variable causative or protective of the disease?
What are the strengths and weaknesses of cohort studies?
Strengths
1. Elimination of recall bias
Weaknesses
1. Behavior can change over time, complicating exposure parameters
2. An apparent “causative” factor, may only be associated with a hidden factor that is actually the cause
Describe case reports
- Do not involve sampling or comparisons
- Reports of isolated cases or rare cases
- Client case, photographs, radiographs, diagrams
Weaknesses
1. Reviews only one client as a means of illustrating disease
2. No control, masking, randomization of subjects
Describe case series
- Reports two or more similar cases (advantage over case report)
- May involve retrospective mining of data from client records
- Selection of cases is not “systematic” – “cherry picking”
- Introduction of bias
Describe interventional studies
- Characteristics of an experiment or clinical trial
- Manipulation of the environment to strengthen the study and eliminate bias
List the types of clinical trials
- Non-controlled trials
- Randomized controlled trials
- Controlled clinical trials
Describe non-controlled trials
- Observation of effects of an intervention without a control group
- Useful when detrimental to client’s health to NOT treat them
Weaknesses
1. Lack of masking
2. Potential lack of any comparison group
Describe randomized control trials
- Randomization of subjects
- Masking of subjects and clinicians
- Introduction of a control group (comparison)
- Superior to all other study design
*Advantage: eliminates placebo effect in both the patient and clinician
Describe variables in interventional studies (randomized control trials)
- All experiments have at least 1 independent and 1 dependent variable
- Concurrent enrollment of subjects and follow-up of subjects in experimental and control groups
- Assignment of subjects through random process (equal chance of selection)
- Purpose of experiments is to estimate the extent to which the independent variable causes changes in the dependent variables
- Physically manipulate independent variable - Giving experimental group new drug and control group a placebo; Teaching 1 class with computers and 1 without
Describe inter-rater reliability
Degree to which examiners are calibrated; achieve same results (e.g., 8 of 10 times)
Describe intra-rater reliability
degree to which an examiner achieves the same results with himself
Describe controlled clinical trials
- Controlled trial without randomization (bias)
- Has a comparison group similar to an RCT
- May or may not be masked
What are the 2 types of research reviews?
- Narrative review
- Systematic review
Describe narrative reviews
- Report – used to overview a topic
- Can acquaint readers with broad aspects of a particular topic
- Can develop background areas of interest
- Free to include or exclude articles without justification
- Approach with caution – less authoritative, reflect bias, no systematic approach to include/exclude articles
- Influenced by authors opinions
- Bias is a potentially big problem in narrative reviews.
Describe systematic reviews
- Uses scientific methodology to systematically identify all relevant literature around a clinical question
- Appraisal of studies
- Evaluation of data
- Development of conclusions
*several clinical studies exploring the same question
How do you conduct a systematic review?
- Develop a clinical question (PICO)
- Determine inclusion/exclusion criteria
- Develop a search strategy (minimum 2 databases)
- Screen titles and abstracts (minimum 2 individuals)
- Screen full text (multiple individuals)
- Critically appraise the studies
- Data abstraction
- Data analysis – similar results can be processed into a meta analysis (ie. quantitative systematic review)
- Develop a conclusion
*ideal SR has 10 studies with 1,000 subjects combined
Clinical Practice Guidelines and Evidence Based Summaries are ___________
growing bodies of information on specific topics.
*Up to date, with statements from professionals that help clinicians to make client care decisions.
*Allow busy healthcare professionals to use their judgement to make informed decisions.
As you progress up the pyramid, the studies are more effective in _________
demonstrating cause and effect
Define reliability
The extent to which outcomes are consistent when the experiment is repeated
Define validity
The extent to which the instruments that are used in the experiment measure exactly what you want them to
