7 Observational Studies and Routine Data Flashcards Preview

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Flashcards in 7 Observational Studies and Routine Data Deck (33)
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1
Q

Q: What is the hierarchy of study design? (7)

A

A:  Systematic reviews and meta-analyses (highest – but can still be inadequate)
 Randomised Controlled Trials
 Cohort studies
 Case-control studies
 Ecological studies
 Descriptive/cross-sectional studies
 Case report/series (lowest – but can still be valuable)”

2
Q

Q: What are descriptive studies in epidemiology?

A

A: examine the distribution of disease across various factors including population or sub-groups, geographical location and time period

3
Q

Q: Best study design to determine the accuracy of diagnostic tests?

A

A: cross- sectional design

4
Q

Q: Best study design to determine disease prognosis.

A

A: cohort study

5
Q

Q: Best study design to determine the causes and risk factors of a disease?

A

A: various non-randomised designs

6
Q

Q: Best study design to determine population healthcare needs?

A

A: various, inc ecological (aggregate) studies

7
Q

Q: Best study design to determine treatment efficiency.

A

A: randomised trial

8
Q

Q: What data is used in descriptive studies? (3) Where does data come from for other study designs?

A

A: Types of data used are:
 Routine e.g. births, deaths
 Survey e.g. Health Survey for England
 Performance management: Quality and Outcomes Framework for GPs

 Other study designs tend to collect their own data

9
Q

Q: List 3 cross sectional survey examples.

A

A: • 2001 Census
• Health Survey for England
• NHS Inpatient Survey on patient experience

10
Q

Q: What is routine data?

A

A: Data that are routinely collected and recorded in an ongoing systematic way, often for administrative or statutory purposes and without any specific research question in mind at the time of collection

11
Q

Q: What are the types of routine data? (8)

A

A:  Health outcome data* e.g. deaths, hospital admissions and primary care consultations or prescriptions, levels of well-being from national surveys
 Exposures and health determinant data, e.g. smoking, air pollution, crime statistics
 Disease prevention data, e.g. screening and immunisation uptake
 Demographic data
, e.g. census population counts
 Geographical data*, e.g. health authority boundaries, location of GP practices
 Health service provision data e.g. bed staff counts
 Births
 Deaths

12
Q

Q: What are the advantages of routine data? Cost? Availability? Collection procedure? (4)

A
A: 	Relatively cheap
	Already collected and available
	Standardised collection procedures
	Relatively comprehensive – population coverage, large numbers
	Wide range of recorded items
	Available for past years
	Experience in use and interpretation
13
Q

Q: What are the disadvantages of routine data? (5)

A

A:  May not answer the question (no information or not enough detail)
 Incomplete ascertainment (not every case captured)
 Variable quality (e.g. variable diagnosis fields) // Validity may be variable (i.e. do they measure what you think they measure?)
 Disease labelling may vary over time or by area
 Need careful interpretation

14
Q

Q: What are examples of health outcome data? (8)

A
A: 	Mortality
	Cancer
	Notification of infectious diseases
	Terminations of pregnancy
	Congenital anomalies
	Hospital episode statistics
	GP data e.g. QOF (Quality of Outcomes Framework)
	Road Traffic Accidents
15
Q

Q: Why are cross sectional studies useful? What do they describe? Downfall?

A

A: useful for health care providers to allocate resources efficiently and plan effective prevention

Describe status of individuals with respect to absence or presence of both exposure and disease assessed at the same point in time

but cannot easily distinguish whether exposure preceded disease: chicken or egg

16
Q

Q: What are cancer registrations? Useful for? Linked to? Good data?

A

A: Voluntary notification to local cancer registry: now national system (Also from death certificates)

both incidence and survival information

Increasingly being linked to hospital admissions data and national clinical audits

Good epidemiological data- allows us to determine most common types of cancer

17
Q

Q: Who reports infectious diseases? Examples of such diseases. (4)

A

A: doctors

Includes food poisoning, meningitis, tuberculosis and plague

18
Q

Q: What is the quality and outcomes framework (QOF) a component of? Rewards? Collection? Published?

A

A: component of the new General Medical Services contract for GPs from April 2004

rewards practices for the provision of quality care, and helps to fund further improvements in the delivery of clinical care

Collected in a national database system: Quality Management Analysis System

Practice-level data are published; being phased out in many areas

19
Q

Q: What is the finished consultant episode?

A

A: the time spent under the continuous care of a specific consultant

20
Q

Q: What is admission?

A

A: A patient’s stay in hospital, so comprises 1+ episodes and/or transfers between hospitals

21
Q

Q: Why are case controls studies good? Suitable for? Requires? What’s compared?

A

A: Relatively cheap and quick to conduct

studying what might cause rare diseases

cases (with disease) and controls (without disease) and compare those who are exposed and unexposed from each group

You are comparing odd of being exposed among cases and controls

22
Q

Q: What are controls in a case control study? Should be?

A

A: subjects free of the disease (or outcome of interest) during the same period of time in which the cases were identified

representative of the population of individuals who would have been identified and included as cases if they had also developed the disease

23
Q

Q: What is the most difficult and critical issue in the design of case-control studies?

A

A: Selection of an appropriate comparison group

24
Q

Q: What are sources of controls? (3) (general population) What do they all vary in? (4)

A

A:  Neighbourhood
 Friends/relatives (depends on disease)
 Hospital or clinic-based

These all vary in amount of recall bias (getting people to remember things about the past), response rates, selection bias, cost

25
Q

Q: What are the advantages of case control studies? (3)

A

A:  Good for rare diseases
 Quick and cost-efficient
 Can investigate many exposures simultaneously

26
Q

Q: What are disadvantages of case control studies? (5)

A

A:  Problems of selection of controls (Selection bias)
 Subject to recall bias
 Uncertainty of exposure- disease time relationship
 Poor for rare exposures
 Cannot calculate incidence rates directly (usually fixed number of controls in sample)

27
Q

Q: What is a cohort? eg? What does it represent?

A

A: “cohort” is a group of people who have something in common:
– All patients registered with the same GP

A cohort represents the outcome-free population from which cases (people with the outcome) eventually arise

28
Q

Q: What does a prospective study compare? Looks at? Speed?

A

A: – Compare rates of disease in the exposed group and unexposed groups.
– Thus, looking at outcome after some time has passed

slower than retrospective

29
Q

Q: What is a retrospective study usually conducted with? Looks at? Speed?

A

A: – Done with routine data usually.
– Use data to look at the relationship between exposure and outcome.
– Quicker way of doing cohort study– Can collect whatever data you like but have to wait a few years to have enough data

30
Q

Q: What are the advantages of cohort studies? (5)

A

A:  Able to look at multiple outcomes
 Able to follow through the natural history of disease
 Good design to look at risks related to rare exposures
 Incidence can be calculated
 Can minimise bias in estimating exposure if prospective

31
Q

Q: What are the disadvantages of cohort studies? (4)

A

A:  Inefficient for studying rare diseases
 Expensive and time consuming (if prospective)
 Loss to follow-up may introduce bias
 Healthy worker/volunteer effect

32
Q

Q: What does the standardised mortality ratio represent?

A

A:  It represents the ratio of the number of observed deaths (or cases of disease) (O) in a particular population to the number that would be expected (E), if that population had the same mortality or morbidity experience as a standard population, corrected for differences in age (and sex) structure.
 Key confounders such as age may vary between populations. Population death rates may be compared taking into account (or “adjusting”) for the effect of age

33
Q

Q: How is the standardised mortality ratio calculated?

A

A: number of observed deaths
_______________________
number of expected deaths if experienced the same age specific rates as standard population