AKT Questions

1. You are reading a research paper regarding a new blood test that can be used to screen for colorectal cancer. It shows the following data:

Cancer present Cancer absent Total no. of cases
Blood test positive 80 40 120
Blood test negative 20 60 80
Total no. of cases 100 100 200

What is the specificity of this new test?

a ) 20%
b ) 33%
c ) 60%
d ) 66%
e ) 75%
f ) 80%

Answer: C

Specificity is a measure of how well the test identifies those who do not have disease as not having disease (60%). Sensitivity is a measure of how well the test identifies those with disease as having disease (80%). The positive predictive value indicates how many people with a positive result have the disease (66%). The negative predictive value indicates how many people with a negative result do not have the disease (75%).

2. OPTIONS:

a ) Vitreous haemorrhage
b ) Proliferative retinopathy
c ) Macular degeneration
d ) Papilloedema
e ) Retinal vein occlusion
f ) Retinitis pigmentosa
g ) Optic neuritis

INSTRUCTION: For each of the patients below, select the fundal condition above that is most likely to be consistent with their symptoms and signs. Each option can be used once, more than once or not at all.


A. A 72 year old woman is a heavy smoker. She complains of increasing difficulty in recognising peoples’ faces and is having difficulty reading. She has been frightened by seeing a dark shape just as she wakens up. She says that her Venetian blinds appear wavy. Her assisted acuity is 6/18 bilaterally .Her BP is 170/100.

The Correct answer is c.
B . A 17 year old man has noticed that his vision has been poor in the evenings for the last six months, and this has resulted in him tripping up frequently. His acuity is 6/6 bilaterally. He has been told that a grandparent and a great-grandparent went blind in their 50’s.

The Correct answer is f.
C. A 56 year old HGV driver describes difficulty reversing his vehicle. He has given it some minor scrapes, and thinks there may be something wrong with his vision. He has been troubled by severe headaches for weeks. His acuity is 6/6 bilaterally. Visual field testing reveals a homonymous hemianopia.

The Correct answer is d.

50% of intracranial tumours have focal neurology at presentation.