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#1
06-06-2011
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,357 Threads: 194 Thanked 3,259 Times in 881 Posts Reputation: 3269
Biostatistics #14 - Screening test

In a diabetes detection program, the screening level for a positive blood sugar level in test 1 is set at 160 mg/dl and in test 2 at 130 mg/dl. The sensitivity is:

a. greater in test 1
b. greater in test 2
c. equal in tests 1 and 2
d. dependent on the size of the population being evaluated
e. dependent on the actual prevalence of diabetes in the population
 The above post was thanked by: excellence (05-18-2014), rulz (06-06-2011), struggle (06-06-2011)

#2
06-06-2011
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I would say B)
 The above post was thanked by: bebix (06-06-2011)
#3
06-06-2011
 USMLE Forums Guru Steps History: Not yet Posts: 324 Threads: 70 Thanked 236 Times in 143 Posts Reputation: 246

Quote:
 Originally Posted by bebix In a diabetes detection program, the screening level for a positive blood sugar level in test 1 is set at 160 mg/dl and in test 2 at 130 mg/dl. The sensitivity is: a. greater in test 1 b. greater in test 2 c. equal in tests 1 and 2 d. dependent on the size of the population being evaluated e. dependent on the actual prevalence of diabetes in the population
i will go with B.
 The above post was thanked by: bebix (06-06-2011)
#4
06-06-2011
 USMLE Forums Addict Steps History: 1 + CS Posts: 113 Threads: 8 Thanked 88 Times in 61 Posts Reputation: 98

I think is b)
#5
06-06-2011
 USMLE Forums Master Steps History: Step 1 Only Posts: 566 Threads: 25 Thanked 522 Times in 263 Posts Reputation: 532

Quote:
 Originally Posted by bebix In a diabetes detection program, the screening level for a positive blood sugar level in test 1 is set at 160 mg/dl and in test 2 at 130 mg/dl. The sensitivity is: a. greater in test 1 b. greater in test 2 c. equal in tests 1 and 2 d. dependent on the size of the population being evaluated e. dependent on the actual prevalence of diabetes in the population
Actually that is pretty similar to the old problem that was happening to the old cutoff value with the glucose test...

If you set a HIGHER value you are making the test MORE SPECIFIC because LESS people are going to fall into that value, so in "real proportion" in the past the cutoff value for glucose was people over 160 mg/dl today we know is 126 mg/dl MAKING the test MORE Sensitive and LESS specific..

That was just a little review :P the ansewr is Greater in the test 2, answer is B.

Answer C: Of course is not equal
Answer D: Didn't think on any reason to choose this one :P but is not this
Answer E: Sensitivity and Specificity are NOT affected by prevalence.
 The above post was thanked by: excellence (05-18-2014)
#6
06-06-2011
 USMLE Forums Guru Steps History: 1+CK+CS+3 Posts: 406 Threads: 30 Thanked 140 Times in 108 Posts Reputation: 150

Quote:
 Originally Posted by bebix In a diabetes detection program, the screening level for a positive blood sugar level in test 1 is set at 160 mg/dl and in test 2 at 130 mg/dl. The sensitivity is: a. greater in test 1 b. greater in test 2 c. equal in tests 1 and 2 d. dependent on the size of the population being evaluated e. dependent on the actual prevalence of diabetes in the population
Yup its B for sure
#7
06-06-2011
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,357 Threads: 194 Thanked 3,259 Times in 881 Posts Reputation: 3269

Yup...congrats!

 The above post was thanked by: struggle (06-07-2011)

 Tags Biostatistics-Epidemiology, Step-1-Questions

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