Study Design

Question 1

case report

Answer 1

an article which describes and interprets individuals cases, often written as a detailed stop

Question 2

case reports are often described as

Answer 2

• unique, unexplainable cases
• cases which show variation in disease
• cases which show unexpected event which yield useful info
• cases in which patentees have two or more unexpected disorders

Question 3

case reports are considered……., but are also

Answer 3

the lowest level of evidence, but are also the first line o evidence

Question 4

why are case reports important

Answer 4

where new issues and ideas emerge- form the base of the pyramid

Question 5

a good case report

Answer 5

is clear about the importance of the observation being reported

Question 6

if multiple case reports show the same thing..

Answer 6

the next step ma be a case-control study to determine if there is a relationship between the relevant variables

Question 7

+ves of case report

Answer 7

• help with identification of new trends of diseases
• detect new drug side effects and potential uses
• educational
• identifies rare manifestations of diseases

Question 8

-ves of case report

Answer 8

• cases may not be generalisable
• not based on systematic studies
• causes or associations may have other explanations
• could be focusing on misleading elements

Question 9

case- control study

Answer 9

a study which compares patients who have a disease or outcome of interest with patient who do not have the disease or outcome of interest. Looks back retrospectively to compare how frequently the exposure to a risk factor is present in each group to determine the relationship between the risk factor and the disease

Question 10

why are case-control study observational

Answer 10

no intervention is attempted and no attempt is made to alter the course of the disease.

Question 11

goal of case-control

Answer 11

to retrospectively determine the exposure to the risk factor of interest from each of the two groups of individuals: cases and controls.

Question 12

case-control studies are designed to determine

Answer 12

odds

Question 13

odds=

Answer 13

positive cases/ negative cases

Question 14

+ve of Case-control

Answer 14

• good for studying rare diseases
• less time needed to conduct the study because the condition or disease has already occurred
• lets you simultaneously look at multiple risk factor
• useful as an initial study to establish an association
• can answer questions that could not be answered through other study design e.g. smoking causing lung cancer

Question 15

-ve of Case-control

Answer 15

• retrospective studies rely on memory- recall bias
• not good for evaluating diagnostic tests because its already clear that the cases have the condition and the controls do not
• can be hard to find a suitable control group

Question 16

why are retrospective studies less useful

Answer 16

recall bias- more problems with data quality because they rely on memory and people with a condition will be motivated to recall risk factors

Question 17

cohort study

Answer 17

where one or more samples are followed prospectively and subsequent status evaluations with respect to a disease are conducted to determine which initial participants exposure characteristics (risk factors) are associated with it

Question 18

as cohort studies commence

Answer 18

outcome for participants in each cohort is measured and relationship with specific characteristic determined

Question 19

+ve of cohort

Answer 19

• subjects can be matched (limiting confounding)
• standardization of criteria possible
• easier and cheaper than RCT

Question 20

-ve of cohort

Answer 20

• hard to identify confounding variables
• no randomisation- imbalances in patient characteristics
• blinding/ masking is hard
• outcome of interest may takes years

Question 21

randomisation

Answer 21

limits imbalances in patient characteristics

Question 22

Randomised control trial

Answer 22

a study which randomly assigns participants into an experimental group or a control group.
The study is conducted and only expected diff between the control and experimental groups is the outcome variable being studied

Question 23

only expected difference between groups in RCT

Answer 23

only expected diff between the control and experimental groups is the outcome variable being studied

Question 24

+ve of RCT

Answer 24

• good randomisation will wash out population bias
• easier to blind
• results can be analysed with statistical tools
• populations of participating individuals are clearly identified

Question 25

-ve of RCT

Answer 25

- expensive: money and time - volunteer biases: the population that participates may not be representative - does not reveal causation - loss to follow- up attributed to treatment

Question 26

Practice guideline

Answer 26

a statement produced by a panel of experts which outline current best current practice to inform health professional and patients in making clinical decisions - produced after extensive review of the literature and is typically created by professional associations, government agencies, and or price organisations.

Question 27

good guidelines clearly

Answer 27

define the topic, appraise and summarise the best evidence regarding prevention, diagnosis, prognosis, therapy, harm and cost-effectiveness; and identify the decision points where this information should be integrated

Question 28

to keep practice guidelines accurate and relevant

Answer 28

they should be reviewed frequently and updated as necessary

Question 29

+ve Practice guideline

Answer 29

- created by panels of experts - based on professional published literature - practical guidance for clinicians - considered evidence based resources

Question 30

-ve practice guideline

Answer 30

- slow to change or be updated - not always available for niche topics - expensive and time-consuming to produce - recommendations might be affected by the type of organisation creating the guideline

Question 31

systematic review

Answer 31

a document written by a panel which provides a comprehensive review of all relevant studies on a particular clinical or health related topic/ question. The systematic review is created after reviewing and combining al the info for both published and unpublished studies and then summarising the findings

Question 32

+ve Systematic reviews

Answer 32

- exhaustative review of the current literature - less costly to review prior studies than conducting a new one - results can be generalised and extrapolated into general population more broadly - more reliable and accurate than individual studies - considered an evidence based resource

Question 33

-ve Systematic review

Answer 33

- very time consuming | - may not be easy to combine studies

Question 34

process of writing a systematic review

Answer 34

1) identify the issue and determine the question 2) write a protocol 3) screen for studies 4) sift and select studies 5) extract data from the studies 6) assess the quality of the studies 7) combine the data 8) discuss and conclude overall findings 9) systematic review 10) dissemination

Question 35

Meta-analyses

Answer 35

a subset of systematic reviews, a method for systemically combining pertinent qualitative and quantitative study data from several selected studies to develop a single conclusion that has greater statistical power - this conclusion should be statistically stronger than the analysis of any single study

Question 36

why are meta-analyses statistically stronger than the analysis of any single study

Answer 36

due to increased number of subjects, greater diversity among subjects, or accumulated effects and results

Question 37

when should meta-analyses be used

Answer 37

- to establish statistical signify with studies with conflicting results - develop more correct estimate of effect magnitude - to provide a more complex analysis of harms, safety data and benefits - examine subgroups with individual number that are not statistically significant

Question 38

if systematic and meta-analyses group ........ they would be the highest level of evidence on the evidence hierarchy

Answer 38

RCT

Question 39

+ve Meta-analysis

Answer 39

- greater statistical power - confirmatory data analysis - greater ability to extrapolate to general pop affected - considered an evidence based resource

Question 40

-ve Meta-analysis

Answer 40

- difficult and time consuming to identify appropriate studies - not all studies provide adequate data for inclusion and analysis - requires advanced statistical techniques - heterogeneity of study population