Case Control and other study design

Made by:Momal Sheikh Nawab khatoonZiyad Furqan

Study Design

Case Control and Cohort Studies

Case ControlAdvantage :• Less Expensive• Efficient for studying rare diseaseDisadvantage:• Inappropriate when disease for specific

exposure not known• Exposure measurement after disease

Cohort ControlAdvantage:• Exposure status determined before disease

detection• Subjects selected before disease detection• Study several outcome of each exposureDisadvantage• Expensive and Time consuming• Inefficient for rare disease

Case•

Select group of

children under 5 from

Village and clinic

•Check children have

diarrhea

•Exposure: Source of

suspected water and

other water

B lind ed N o t b lind ed

R a nd o m ised N o t ran d om ised

C o n tro lled N o t co n tro lled

T ria l

Types of TrialsClinical study design is the formulation of trials and experiments, as well as observational studies in medical, clinical and other types of research (e.g., epidemiological) involving human beings.

Controlled• An experiment or clinical

trial in which two groups are used for comparison

purpose. • one group of participants

is exposed to a substance (e.g. a pollutant) while those in the "control"

group are not

Uncontrolled researchers have no such

control over whether their subjects receive the treatment

being investigated. �Uncontrolled studies thus are

subject to worries about confounding variables.

Potential bias in case controll studies

Selection bias can occur in a case-control study if controls are more (or less) likely to be selected if they have the exposure.

Selection Bias

Door-to-door survey of neighborhood around the hospital during work day.

Information BiasIn epidemiology, Information bias refers to bias arising from measurement error.

Recall Bias

• involves interviews or questionnaires, regarding events or experiences from the past

• Patient have accurate recall.

Limitation Bias

• The person being interviewed may simply not have the information being requested

ECOLOGIC

STUDIES

CROSS-SECTIONAL

STUDIESCROSS-SECTIONAL

STUDIES

factor present

Other Study

Design

CASE-

CROSSOVER

DESIGN

Study only exists at this point in time

Case Crossover

USED FOR

STUDING THE

ETIOLOGY OF

ACUTE OUT COME

SUCH AS

MYOCARDIAL

INFRACTION OR

DEATHS FROM

ACUTE EVENT

OVER A SHORT

PERIOD OF TIME.

Ecological Studies

Example: The Outbreak

of Influenza and later

development of acute

lymphocytic leukemia in

a child not known if the

mother of any of these

children had influenza

during their pregnancy.

What we are missing is

the individual data of

exposure