KONCPT NEXT MCQ’s for the day: PREVENTIVE AND SOCIAL MEDICINE
TOPIC: Screening for disease
DR SWETHA NB
1. The ability of the test to call positive those who really have the disease is known as :
a) sensitivity
b) validity
c)specificity
d) none of the above
1.Answer a) Sensitivity
The ability of the test to call positive those who really have the disease is known as : Sensitivity
The ability of the test to call negative those who do not have the disease is known as : Specificity
2.Parameters on which a diagnostic test is evaluated are all except
a) reliability
b) efficiency
c) validity
d) strength of association
2. Answer d) strength of association
Parameters on which a diagnostic test is evaluated are: reliability , efficiency and validity
3. Prevalence will affect the ________________ of a test
a) Sensitivity
b) Predictive values
c) Specificity
d) Validity
3. Answer b) Predictive value
Positive predictive value is directly proportional to prevalence. So, as prevalence increases PPV increases and false positives decrease.
Negative predictive value is inversely proportional to prevalence. So, as prevalence increases NPV decreases and false negatives increase.
When disease prevalence is low, predictive value depends on specificity.
As specificity increases- PPV increases
4. Screening for disease comes under which level of prevention?
a) Primordial
b) Primary
c) Secondary
d) Tertiary
4. Answer c) Secondary
Screening is early diagnosis- hence secondary level of prevention.
5. A new test for diabetes was carried out. Out of 80 people who were tested positive, it was found that actually 40 had diabetes and out of 9920 who were tested negative , 9840 did not have disease actually. The sensitivity of this new test is:
a) 33%
b) 50%
c) 65%
d) 99%
5. Answer a) 33%
| Diabetes present | Diabetes absent | Total | |
| Test positive | 40 | 40 | 80 |
| Test negative | 80 | 9840 | 9920 |
Sensitivity= TP__X 100= 40 X100 = 33%
TP+FN 40+80