Analytical study Flashcards by Iseoluwa Ojo

ANALYTICAL STUDIES
• Measure ______ and ______ on populations based on hypothesis generated during previous descriptive studies

• Determine the existence and strength of association between _________________________ and the _____________ in question

Cause and effect

suspected risk or etiological factor and the
disease

How well did you know this?

Not at all

Perfectly

Analytical Studies

• Have _________ or __________ group(s) which must be similar to cases in all aspect except for the __________________________

control or comparison

outcome or disease under study

How well did you know this?

Not at all

Perfectly

Analytical studies

• Include ____________ study, ________ study.

case-control

cohort

How well did you know this?

Not at all

Perfectly

Basic Questions in Descriptive & Analytical studies
•Descriptive studies ask the questions
_____,______,_________ ?
•Analytical studies in addition asks _______?

who, when and where

why

How well did you know this?

Not at all

Perfectly

Case-Control Study

• An _________ ,__________ study in which comparisons are made between _________________ and ____________________

observational, analytical

individuals who have the disease (cases)

individuals who do not (controls)

How well did you know this?

Not at all

Perfectly

Case-Control Study

• Is a _____________ study; goes _____wards in time from ________ to _________

retrospective; back

effect (disease) to cause

How well did you know this?

Not at all

Perfectly

Case-Control Study

• Compares the _________ of previous exposure to the suspected etiological factor in persons with the disease
(cases) and those without the disease (controls)

frequency

How well did you know this?

Not at all

Perfectly

Case control study
Steps in conducting a case control study
1. —————— of ——— and ——-
2. ———-
3. Measurement of ———-
4. Analysis and interpretation

Selection of cases and control
Matching
Measurement of exposure
Analysis and interpretation

How well did you know this?

Not at all

Perfectly

Selection of cases and control
• A case is first of all defined by means of ___________
• Cases must belong to same ________ and ___________ group
• Eligibility criteria must be adhere to
• Cases are obtained from hospital records, , death certificate, employer records and the general population
• Information about cases can be gathered from cases
themselves, relatives and friends or from records.

diagnostic criteria

clinical and histological

How well did you know this?

Not at all

Perfectly

Selection of control

• The control must be _____________ under study
• Should resemble the cases in ______________
• The control must (be or not be?) exposed to the suspected causative factor of
the disease under study.

free of the disease

other characteristics

Not be

How well did you know this?

Not at all

Perfectly

Which is easier?

Selecting cases or selecting controls

Selecting cases

How well did you know this?

Not at all

Perfectly

Hospital control
• Hospital control are more likely to have similar characteristics as the study group in terms of their ______________ and ______________ factors
• They tend to be (more or less?) exposed to the risk factors of disease than the general population
• They may differ from the ______________ population
• They are easily identified and are almost always available for interview and tend to be cooperative

catchment area and socioeconomic

normal healthy

How well did you know this?

Not at all

Perfectly

Relatives and friends
• Relative as well as friends of cases under study (may or may not?) be used as control
• Siblings (must or must not?) be used when studying genetic condition
• The disadvantage is that they may be __________ in terms of __________ and other characteristics

May

Must not

too similar; exposure

How well did you know this?

Not at all

Perfectly

Neighbours
• Selected from persons living in the same area, working in the same
place, or attending the same school with the cases

Okay

How well did you know this?

Not at all

Perfectly

General population
• Population control have the advantage of using ____________ that represent well the population of the area
• They are usually selected by means of __________ sampling
• In developed world, ________________ can be randomly selected

healthy people

random

telephone number

How well did you know this?

Not at all

Perfectly

Matching
• Matching is the process of selecting controls in such a way that they
are ______________ with regards to certain pertinent variables e.g. sex, race, occupation, socio-economic status and educational status
• These factors influence the outcome of disease

similar to cases

How well did you know this?

Not at all

Perfectly

Measurement of exposure
• Information about exposure is obtained in a (similar or dissimilar?) way among the
cases and control.
• This may be done by means of interview, questionnaires, focus group discussion , check lists and studying past records such as hospital and employment records

similar

Analysis and interpretation

 The Odds ratio is an estimate of the _____________.
 It is known as ________________ ratio
 It is a measure of __________________ between __________ and —————— .

relative risk

cross production

strength of association

risk factor and outcome

Odds ratio= _____/____

Where each letter stands for ?

ad/bc

a = number of exposed individuals who eventually
developed the disease
b= number of exposed individuals who did not develop
the disease
c=number of unexposed individuals who subsequently
develop the disease
d= number of un exposed individuals who did not
develop the disease

Odds Ratio
• OR=___________________________ x ___________________________/___________________________ x ___________________________ (ad/bc)

Exposed persons with the disease

unexposed without the disease

Exposed without the disease

unexposed with disease (ad/bc)

Odds Ratio

• Is a ratio of the odds that _________________________ to the odds that a ___________________

a case was exposed to the risk factor

control was exposed to the risk factor

Odds ratio

• Referred to as _____________ Ratio; ______________ , _______________

Cross Product

Relative Odds

Estimated Relative Risk

Advantages of Case-Control study

-Relatively _____,______,____________

-Suitable for studying _____-
diseases

-________ problems is minimal

-Require ____ sample size
measurement

easy, quick, inexpensive

rare; Ethical

small

Disadvantages of Case-Control Study

-________ bias; also information may be _________ or __________

-Bias in _________________________

-Can not measure _________

-Can not give accurate _______

Recall; missing or unavailable

selection of control group

incidence; risk

COHORT STUDY • Type of analytical /observational study. • Determines if there is an association between ______________ and ________________ • Also called _________ study, _________ study, _________ study.

a suspected cause( exposure) and disease prospective; incidence ; forward looking

COHORT STUDY • The study proceeds from ______ to _________

cause to effect

cohort • A group of people who share a ___________________________ within a _____________ period. e.g age( _______ cohort), class mates ( _______ cohort), exposure to infection within a defined period ( __________ cohort)

common characteristic or experience defined time ; birth; class; exposure

• Cohorts are identified (prior to or after?) appearance of disease/outcome under study and followed up.

prior to

Cohort study • Begin with _______ groups (cohorts) – _________ and ___________ groups that have similar composition except for ______________________ • follow up both groups to see how many people in both groups develop disease/outcome under investigation • May require long period of follow up • Some participants lost to follow up (attrition)

two exposed and unexposed exposure to suspected etiology

Analysis of COHORT • Quantification of association between suspected agent and disease being investigated • Record frequency of disease occurrence in both groups in two by two table- ______________ • Calculate relative risk, attributable risk and make conclusion on cause – effect relationship

incidence

Association between smoking and stroke • Incidence in exposed= ______________ /___________ = ____/________ • Incidence in unexposed= ________________ /____________= _____ / ______

• Incidence in exposed= Num of cases/num exposed A /A+B • Incidence in unexposed= Num of cases/num not exposed C / C+D

Relative Risk (RR) • RR does not necessarily imply ___________ as it does not ___________________________ • Also called _____ Ratio or __________ Ratio

causal association quantify the extent of disease causation by the risk factor Risk; Morbidity

Analysis - 1.Relative risk • Relative risk – relates the ____________________________ to ____________________________

incidence rate in the exposed incidence rate in the unexposed

Analysis - 1.Relative risk • RR =______________ / _____________ • If RR >1 _______________________ • If RR = 1 __________________________ • If RR < 1 ____________________

incidence in exposed incidence in unexposed risk of acquiring the disease is higher in those who are exposed whether exposed or not risk is same

2. Attributable risk • _______________________________ •_______ risk in those who are exposed • The amount of risk which can be ascribed to _________

Incidence rate in the exposed minus incidence rate in unexposed Excess; exposure

• Attributable risk = ____________________________________________ = __________________

Incidence in exposed – Incidence in unexposed risk difference

Relative risk & attributable risk • Relative risk measures __________________. • Attributable risk measures the impact that _____________________ may have on the _______________

strength of association removal of a certain factor incidence of a disease

The higher the relative risk the ___________ the association of factor to disease. high relative risk suggests _________

greater etiology

Advantages of cohort studies • Can determine ____________ of disease in exposed and unexposed • No problem of _______ bias • Can measure ______________ • Can test multiple effects of cause

incidence; recall relative risk

Disadvantages of cohort studies • Need ______ sample • ________ • Time consuming • Difficulty in ____________ of people - attrition

large Expensive follow up