A radiologist develops a new screening test for cancer of...

A radiologist develops a new screening test for cancer of the pancreas. The sensitivity and specificity of the test are said to be “very high, at least 98%”. You are asked to determine whether it would be useful to screen everyone in your primary care practice with this test in the next year. To answer this, you would need to know which of the following: Select one: A. The survival rate from pancreatic cancer cases detected by the new test B. The prevalence of asymptomatic pancreatic cancer in your practice C. The incidence of asymptomatic pancreatic cancer in your practice D. The incidence and prevalence of asymptomatic pancreatic cancer in your practice

Transcript

00:01 So welcome to this question once again.

00:04 Okay, so we're going to break down the question in steps so that you're able to follow up more closely.

00:15 So from the question we're given that sensitivity and specificity of this test can enable us, you know, come up with a continuous table that you can use to answer prevalence, for instance, okay? okay contingency sorry you can do contingency table contingency table okay we also given that you need to qualitative you know negative positive predictive prevalence rates which we can do for this question so normally or rather just to start us off we give the subjects study subjects are 10 ,000.

01:20 Okay.

01:22 Then we give you a specificity.

01:29 Specificity we're given as 0 .43.

01:35 Sensitivity.

01:40 So sensitivity we're given as 0 .88.

01:44 Okay.

01:45 Sensitivity rate.

01:46 So we ask ourselves that if positive tests, if all the positive tests were at 700, then can you be able to determine the deceased mean with the number of positive tests, can we? there's a question of philosophy of self.

02:12 Step number one.

02:14 We're going to determine desist men, desist men, okay? the desist man with those bearing positive test.

02:28 Okay? and these are going to calculate it as sensitivity.

02:38 Sensitivity one by total number of people.

02:42 Total number of people okay so this is going to be equal to same as 0 .88 from the values given multiple by 700 okay this is going to give us a value of 616 so if we have 616 that were positive for this test don't you agree that for us to determine the number of negative tests, negative people or negative people whose test came up negative could be 700 total, 1 ,616 and this is going to give us around 84.

03:38 So 84 are people who just said negative for these test cancer or whatever.

03:46 So therefore, total number, total number number of people without cancer total number without cancer without cancer is going to be given as 10 ,000 minus 700 which is 10 ,300 people so these are just figures we're getting to enable us calculate so therefore number of people so people with without people without it should be people without people without people without cancer but a negative for the test is as given as specificity multiplied by specificity people without cancer this is going to be 0 .43 multiply by 9 ,300...

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