Download SCREENING FOR DISEASES

SCREENING FOR
DISEASES
Dr.MUSTAQUE AHMED
MBBS,MD(COMMUNITY MEDICINE),
FELLOWSHIP IN HIV/AIDS
OBJECTIVE OF THE CLASS


TO UNDERSTAND THE DEFINATION OF SCREENING
AND LEAD TIME.
TO KNOW OBJECTIVES OF SCREENING AND TYPES OF
SCREENING.
2
SCREENING
DEFINATION: The search for unrecognized disease or defect
by means of rapidly applied tests, examinations or other
procedures in apparently healthy individuals
3
“LEAD TIME”
The advantage gained by screening
First possible time of
diagnosis
Usual time of
diagnosis
Outcome
A-usual outcome
B- better outcome
“LEAD TIME”
4
CONCEPT OF LEAD TIME
•Lead time is the period between diagnosis by early detection and
diagnosis by other means.
•This period , determine both the severity of the disease and the
success of any treatment in reversing the disease process.
•Hence, screening programmes should therefore concentrate
on those DISEASE where the LEAD TIME IS LONG.
5
AIMS AND OBJECTIVES:
Early detection and lifestyle changes.
Early intervention and management.
To reduce the risk of disease .
To decrease mortality and suffering.
6
Which diseases to be screened?
1.
2.
3.
4.
5.
6.
Important public health problem
Recognizable early asymptomatic case
Test to detect disease prior to onset of signs and symptoms
Facilities available for confirmation of diagnosis
Effective treatment available
Early detection reduces morbidity and mortality
7
TARGET GROUPS:
 Persons with a family history of a disease.
 Persons with occupational exposure to disease causing
substance.
 Pregnant women.
 Workers responsible for the lives of others i.e., pilots,
bus drivers.
8
SCREENING AND DIAGNOSTIC TEST:
A screening test is not intended to be a diagnostic test.
It is only an initial examination.
Screening and diagnostic test my be contrasted as:-
Screening test
Diagnostic test
• Done on apparently healthy.
• Done on those with
indications of sick.
• Applied to groups.
• Applied to single patients.
• Less accurate.
• More accurate
9
• Based on one criterion.
• Based on evaluation of a
number of symptoms and lab
findings.
•Less expensive.
• More expensive.
•Not a basis for treatment.
•Used as a basis for treatment.
•The initiative comes from
the investigator or agency
providing care.
•The initiative comes from a
patient with a complaint.
10
USES OF SCREENING:
 Case detection.
 Control of disease.
 Research purposes.
 Educational opportunities.
11
CASE DETECTION:
•Also known as ‘ prescriptive screening’.
•Here the people are screened primarily for their own benefit.
•Specific diseases sought by this method arebreast cancer
cervical cancer
diabetes mellitus
iron deficiency
12
CONTROL OF DISEASE:
•Also known as ‘ prospective screening’.
•People are examined for the benefit of others.
eg,1) screening of immigrants from infectious diseases like
T.B and syphilis to protect the home population.
2) screening for streptococcal infection to prevent
rheumatic fever.
13
RESEARCH PURPOSES:
•Screening may sometimes be performed for research
purposes.
eg, to know the history of many chronic diseases like
cancer, HTN etc.
EDUCATIONAL OPPORTUNITIES:
•Screening programmes help in
- providing opportunities for creating public
awareness.
- for educating health professionals.
14
TYPES OF SCREENING:
3 TYPES Mass screening.
 High risk / selective screening.
 Multiphasic screening.
15
MASS SCREENING
Def- Organized periodic procedures performed on large Groups of
people for the purpose of detecting disease. Eg.TB
It is offered to all irrespective of the particular risk individuals.
•This procedure received support in the past, but it was
subjected to critical review.
•Indiscriminate mass screening, therefore is not a useful
preventive measure unless backed up by suitable
treatment that will reduce the duration of illness.
16
HIGH RISK / SELECTIVE SCREENING:
•Screening will be most productive if applied selectively to
high risk groups, the groups defined on the basis of
epidemiological research.
eg, 1) cancer cervix tends to occur relatively less often in
the upper social groups, screening for cancer cervix in the
lower social groups could increase the yield of new cases.
2) increase serum cholesterol level in individual---for CHD
17
MULTIPHASIC SCREENING:
Def- simultaneous examination of a population for several
different diseases by using 2 or more screening test.
e.g., chemical and haematological tests on blood and urine specimens)
Randomized controlled studies in U.K and USA suggested that multiphasic screening has not
shown any benefit accruing to the population in terms of mortality and
• morbidity reaction. It has also increased the cost of health services without
any observable benefits.
18
19