Observational studies and routine data Flashcards

1
Q

test accuracy of diagnostic test?

A

cross-sectional design

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2
Q

test prognosis of disease?

A

cohort study

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3
Q

test aetiology and risk factors of disease?

A

various non-randomised designs

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4
Q

test population healthcare needs?

A

various, ecological studies

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5
Q

test treatment efficacy?

A

RCT

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6
Q

What is a descriptive study ?

A

describe distribution of factors or disease in relation to

  • person (age, sex, race, marital status, lifestyle, job)
  • place (variation between/within countries)
  • time (variation over time and season)
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7
Q

What types of data can be used for a descriptive study?

A

routine (births, deaths)
survey
performance management (Quality and Outcomes Framework for GPs)

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8
Q

What is routine data?

A

= data routinely collected and recorded in ongoing systematic way without research question in mind at time of collection

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9
Q

What are types of routine data?

A
  • health outcome data (deaths, hospital admissions, primary care consultations, prescriptions, well being levels from national surveys)
  • exposures and health determinant data (smoking, air pollution, crime stats)
  • disease prevention data (screening and immunisation uptake)
  • demographic data (census population counts)
  • geographical data (health authority boundaries, location of GP practices)
  • health service provision data (bed staff counts)
  • births
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10
Q

Advantages of routine data

A
cheap
already collected/available
standardised collection procedures
comprehensive (population coverage, large numbers)
wide range of recorded items
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11
Q

Disadvantages of routine data

A
  • may not answer the question
  • not every case captured
  • variable quality due to variable diagnostic fields
  • validity may be variable
  • disease labelling may vary over time/by area
  • coding changes may create artificial increase/decreases in rates
  • need careful interpretation
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12
Q

Examples of heath outcome data

A
mortality
cancer
notification of infectious diseases
termination of pregnancy
congenital abnormalities
road traffic accidents
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13
Q

Why are cross sectional studies important?

A

e. g. census every 10 years
- useful for care providers to allocate resources efficiently and plan effective prevention
- provide clues leading to hypotheses which can be used in analytical studies
- describe status of individuals re absence/presence of exposure and disease

However cannot distinguish between whether exposure preceded disease

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14
Q

How is mortality recorded?

A

death certificates

  • local registrars of births and deaths
  • Office of National Statistics for coding/processing
  • produced as routinely published tables (mortality stats)
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15
Q

How is cancer registered?

A
  • voluntary notification to local cancer registry
  • also from death certificates
  • used for incidence and survival information
  • linked to hospital admissions and national clinical audits

Info allows identification of most common cancer types

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16
Q

How are infectious diseases notified?

A

reported by doctors

incidence of disease

17
Q

What is the Quality and outcomes framework?

A
  • component of General Medical Services contract for GPs from April 2004
  • rewards practices for provision of quality care and helps to fund further improvements in delivery of clinical care
  • collected in national database system called Quality Management Analysis System
18
Q

What is Administrative hospital admissions data?

A

UK’s way of classifying treatment

19
Q

What is a finished consultant episode?

A

the time spent under the cont care of a specific consultant

20
Q

What is admission?

A

comprises of 1+ episodes and/or transfers between hospitals

21
Q

What are the benefits of case control studies?

A

cheap
quick to conduct
investigate many exposures simultaneously
good for rare diseases

22
Q

What are the disadvantages of CCs?

A

need cases and controls to compare those who were exposed and unexposed to the risk factors suspected

selection bias of controls

subject to recall bias

uncertainty of exposure (disease time relationship)

poor for rare exposures

cannot calculate incidence rates directly as fixed number of controls in sample

23
Q

What is the principle of CCs and general procedure (3)?

A

comparing odds of exposure between cases and controls

  1. select cases with disease, controls without
  2. obtain information on past exposures, other factors
  3. compare proportions of people exposed in cases and controls
24
Q

How are controls selected in case control studies?

A

control must be free of disease (outcome of interest) during same period of time in which cases were identified

representative of population of individuals identified as cases

25
Sources of controls?
general population - neighbourhood - friends/relatives - hospital
26
What does the choice of control vary in?
Amount of recall bias response rates selection bias cost
27
What is a cohort?
group of people with something in common | represents outcome-free population from which cases will arise
28
What are the types of cohort study ?
prospective - compare disease rates in exposed and unexposed groups after time retrospective - with routine data to look at relationship between exposure and outcome
29
Advantages of cohort?
look at multiple outcomes follow natural disease history good design to look at risks related to rare exposures calculate incidence minimise bias in estimating exposure if prospective
30
Disadvantages of cohort?
``` inefficient for rare disease expensive time consuming if prospective loss to follow up introduces bias healthy worker/volunteer effect affects generalisability ```
31
What is the STANDARDISED MORTALITY RATIO?
= rate ratio adjusted for age that shows the number of observed deaths (cases of disease), O, in a population to the expected number if the population has the same morbidity/mortality as a standard population corrected for differences in age/sex
32
What does SMR allow?
compare population death rates as it is adjusted for age/sex
33
Formula for SMR?
number of observed deaths/number of expected deaths if same age specific rates as standard population