CAT (PP) lecture

Question 1

Inverse Care Law

Answer 1

• The availability of good medical care tends to vary inversely with the need for it in the population served
• The inverse care law operates more completely where medical care is most exposed to market forces, and less so where such exposure is reduced

Question 2

What are the components of a person’s socio-economic status?/ individual level measurements

Answer 2

• education level
• occupational class
• income level
• N-SEC (new socioeconomic classification based on occupation)

Question 3

What do area-based measures measure?

Answer 3

Level of material and social disadvantage of the area in which a person lives

Question 4

Examples of ‘area-based’ measurements

Answer 4

• English Index of Multiple Deprivation (IMD) (linked to post-code)
• Scottish Index of Multiple Deprivation (SIMD)
• Carstairs Index (Scotland)
• Townsend Index of material deprivation

Question 5

What’s interpretive paradigm?

Answer 5

• The interpretive paradigm is concerned with understanding the world as it is from subjective experiences of individuals
• They use meaning (versus measurement) oriented methodologies, such as interviewing or participant observation, that rely on a subjective relationship between the researcher and subjects

Question 6

What is interpretivism in research?

Answer 6

• Interpretivism is one form of qualitative methodology
• Interpretivism relies upon both the trained researcher and the human subject as the instruments to measure some phenomena, and typically involves both observation and interviews

Question 7

What are the criteria to evaluate the quality of a service provision?

Answer 7

Maxwell criteria (3As and 3Es)

• accessibility - can people even access it eg appointment etc
• appropriate - is it relevant
• acceptability - and what people want, is it viewed positively
• equity - is it fair
• efficiency - is it efficient - cost effective
• effectiveness - does it even work

Question 8

What is ecological fallacy?

Answer 8

When inferences about the nature of individuals are deduced from inferences about the group to which those individuals belong

Question 9

What’s type 1 error?

Answer 9

A rejection of a true null hypothesis

(so we think that our findings are brilliant, but it turns up that the nill hypothesis is true)

Question 10

What’s type 2 error?

Answer 10

type II error is the failure to reject a false null hypothesis

(so we think that our findings are shit - pessimist, but in fact it’s good as we are opposite to null hypothesis)

Question 11

What’s the aim of Bradford-Hill criteria?

Answer 11

outlines 9 minimal conditions needed to establish a true causal relationship

Question 12

Describe the meaning of each of Bradford-Hill criteria (9)

Answer 12

• TEMPORALITY does the cause come before the effect?
• REVERSIBILITY if the cause is removed does the effect go away?
• DOSE-RESPONSE RELATIONSHIP/BIOLOGICAL GRADIENT

If exposure to the cause goes up does the effect?

• STRENGTH

How strong is the association between the cause and effect (relative risk)?

• PLAUSIBILITY

Does the association conform with current knowledge?

• CONSISTENCY

If the study was replicated in a different time and place

would the same association be observed?

• STUDY DESIGN

Does the evidence come from a strong, robust study?

• SPECIFICITY

Considered to be the weakest of the criteria; a single

cause produces a specific effect

• ANALOGY

Applying accepted evidence from another area of study

Question 13

What’s The Short Form (36) Health Survey?

Answer 13

• is a 36-item, patient-reported survey of patient health
• SF-36 is a measure of health status
• an abbreviated variant of it, the SF-6D, is commonly used in health economics as a variable in the quality-adjusted life yearcalculations -> to determine the cost-effectiveness of a health treatment

Question 14

What’s the Bayesian approach?

Answer 14

It’s a statistical method that updates the probability for a hypothesis as more evidence or information becomes available

‘How likely is that disease now I know this abnormal test given that disease is present?’

Question 15

What’s the frequentist approach?

Answer 15

‘how likely is an abnormal test given that disease is present?’

Frequentist inference is a type of statistical inference that draws conclusions from sample data by emphasizing the frequency or proportion of the data

Question 16

What’s CONSORT?

Answer 16

Consolidated Standards Of Reporting Trials

Various initiatives developed by the CONSORT Group to alleviate the problems arising from inadequate reporting of randomized controlled trials

Question 17

What’s consort statement?

Answer 17

• CONSORT statement - it’s the main product of CONSORT group

(group that aims to address the problems that arise from inadequate RCT reporting)

• minimum set of recommendations for reporting randomized trials
• a standard way for authors to prepare reports of trial findings-> reducing the influence of bias on their results, and aiding their critical appraisal and interpretation
• it’s 25-item checklist

Question 18

What does GRADE mean? Full name

Answer 18

GRADE (Grading of Recommendations, Assessment, Development and Evaluations)

Question 19

What’s GRADE?

Answer 19

• a transparent framework for developing and presenting summaries of evidence
• a systematic approach for making clinical practice recommendations
• the most widely adopted tool for grading the quality of evidence and for making recommendations

Question 20

What’s incidence?

Answer 20

Incidence – Number of new cases

Question 21

What’s the prevalence?

Answer 21

Prevalence – Number of existing cases

Question 22

Point vs period prevalence

Answer 22

POINT PREVALENCE:

“a snapshot in time” showing the amount of people in that one investigation who have the illness (e.g. cross-sectional studies)

PERIOD PREVALENCE:

Refers to a specific PERIOD (usually a year)

Question 23

What’s case fatality rate?

Answer 23

Number of deaths from a disease/Number of diagnosed cases of the disease

*produces a percentage of people that die from a specific disease

* denominator - new cases

Question 24

What are the confounders associated with?

Answer 24

With exposure and outcome

Question 25

What are QUALYs ?

Answer 25

QALY:

• Capture expected years of life left and the quality of that time
• Derived from mortality, morbidity and a quality of life value

Question 26

What’s case-mix?

Answer 26

Case-mix

• adjustment is an attempt to control for a particular type of confounding, namely that some patients have a set of covariate risk factors that predispose them to the outcome
• comparison of treatment outcomes between providers with differing mix of patients with regard to diagnoses, severity of illness, and other variables associated with the probability of improvement with treatment

Question 27

What’s information bias?

Answer 27

Information bias

• results from systematic differences in the way data on exposure or outcome are obtained from the various study groups
• individuals may be assigned to the wrong outcome category -> leading to an incorrect estimate of the association between exposure and outcome

Question 28

What’s observer bias?

Answer 28

Observer bias

• may be a result of the investigator’s prior knowledge of the hypothesis under investigation or knowledge of an individual’s exposure or disease status
• Such information may influence the way information is collected, measured or interpretation by the investigator for each of the study groups

Question 29

What’s recall bias?

Answer 29

• patient’s ability to accurately recall past exposures
• recall bias may occur when the information provided on exposure differs between the cases and controls

Question 30

What’s social desirability bias?

Answer 30

Social desirability bias

• respondents to surveys tend to answer in a manner they feel will be seen as favourable by others, for example by over-reporting positive behaviours or under-reporting undesirable ones

Question 31

What’s performance bias?

Answer 31

Performance bias

• study personnel or participants modify their behaviour / responses where they are aware of group allocations

Question 32

What’s detection bias?

Answer 32

Detection bias occurs where the way in which outcome information is collected differs between groups

Question 33

What’s instrument bias?

Answer 33

Instrument bias refers to where an inadequately calibrated measuring instrument systematically over/underestimates measurement.

Question 34

What’s selection bias?

Answer 34

Selection bias occurs when there is a systematic difference between either:

• Those who participate in the study and those who do not (affecting generalisability) or
• Those in the treatment arm of a study and those in the control group (affecting comparability between groups).

Question 35

What’s sampling bias?

Answer 35

Sampling bias - the scenario in which some individuals within a target population are more likely to be selected for inclusion than others

For example, if participants are asked to volunteer for a study, it is likely that those who volunteer will not be representative of the general population, threatening the generalisability of the study results. Volunteers tend to be more health conscious than the general population.

Question 36

What’s allocation bias?

Answer 36

Allocation bias occurs in controlled trials when there is a systematic difference between participants in study groups (other than the intervention being studied). This can be avoided by randomisation.

Question 37

What type of data collection is used in cohort study?

Answer 37

Longitudinal

Question 38

What in randomisation (in adjustment for confounding)?

Answer 38

• all potential confounding variables should be equally distributed between the study groups
• it involves the random allocation (e.g. using a table of random numbers) of individuals to study groups

Question 39

What in restriction (in adjustment for confounding)?

Answer 39

• Restriction limits participation in the study to individuals who are similar in relation to the confounder

For example, if participation in a study is restricted to non-smokers only, any potential confounding effect of smoking will be eliminated.

Question 40

What in matching (in adjustment for confounding)?

Answer 40

• Matching involves selecting controls so that the distribution of potential confounders (e.g. age or smoking status) is as similar as possible to that amongst the cases
• Usually in case-control studies

1. Pair matching - selecting for each case one or more controls with similar characteristics (e.g. same age and smoking habits)
2. Frequency matching - ensuring that as a group the cases have similar characteristics to the controls

Question 41

What’s stratification? (in relation to confounders)

Answer 41

Stratification allows the association between exposure and outcome to be examined within different strata of the confounding variable, for example by age or sex

Question 42

What’s standardization? (in relation for confounders)

Answer 42

Standardisation accounts for confounders (generally age and sex) by using a standard reference population to negate the effect of differences in the distribution of confounding factors between study populations.

Question 43

What’s residual confounding?

Answer 43

Residual confounding

• It is only possible to control for confounders at the analysis stage if data on confounders were accurately collected
• Residual confounding occurs when all confounders have not been adequately adjusted for, either because they have been inaccurately measured, or because they have not been measured (for example, unknown confounders)