I feel like I'm being denied candy on Halloween. Maybe I'm completely clueless. Maybe I am like one of those 80% physicians who don't know basic math and still managed their way through med school. Quite possible.
But the final diagnostic test result is what is shared to a patient. Just a list of tests - abbreviations of test names - done will be in the bill. How can a patient go to the extent of verifying the sensitivity of the issue based on test details? Although I am sure I belong in the 80%-physicians-getting-it-wrong group, I am shameless when it comes to trying! There is 18% probability of having the disease Here's how: Probability of the disease = 1/100 = 0.01 Probability of testing positive with disease = 90/100 = 0.90 Probability of testing positive (overall) = 5/100 = 0.05 Probability of having the disease when tested positive = 0.90 * 0.01 / 0.05 = 0.18
You are right. They often cannot and that is a problem! All the more reason to make sure your physician can explain the test and its limitations and interpretation to you well, in a way that you can fully understand! I phrased the question in a particularly easy way for an intelligent lay audience, to make it unambiguous and solvable. When using tests, most people don't have it expressed in quite the way I put it. I will explain later what I mean and why people panic. As for your answer, let's wait and see if others agree (or even try it). Let's give it a day maybe?
(% FB users with BR) x (Chance of +ve test) ------------------------------------------------------- (% FB users with BR x Chance of true +ve) +( % of FB users without BR x Chance of false +ve) (0.01 x 0.90) / ((0.01 x 0.90) + ( .99 x .05)) 15.39 % is the probability that you have BR if you test positive. Soka, my answer better be correct; a few trick-or-treaters went away without candy as I didn't open the door.
Main kaun hoon? Main kaha pe hoon? Mujhe kuch yaad nahi hai..,., Seriously, I had to sit and read the book first to answer a math homework question yesterday. It doesn't come back anymore I don't understand the question and then there are so many numbers there. Something doesn't add up. How can middle schoolers decipher all that information? When I was a middle schooler I didn't know what a probability was. Did you? I thought all the "fundu gyaan" is only for aaj kal ke Bacchae.
OK, the implication was not that a middle schooler could answer that question right off! I was trying to say that all you need is addition, multiplication and division. Fancy mathematical machinery not required, although it can be approached that way. Well, we were taught the basics of a 'counting' approach. Colored marbles in a box, socks in a bag sort of thing. I will explain tomorrow. The exercise is designed to illustrate a couple of points and that is one of them!
While I am totally towards this idea aka option of discussing or interpreting the test results, I also want to point out the challenges. Some countries require the physicians to sit the patient and/or family down and walk them through the tests and the results, plus also narrate how they came to the conclusion that the patient is affected. Its close to impossible in countries like India. Doctors often march to their own drums. Most don't like to be questioned, most get irritated when questioned. Some doctors have even said why is all that information necessary to you or you will not understand those things. Maybe in case of a terminal illness or a fatal injury that requires a very(!) major surgery, they are willing to open up about what is happening or what tests are done. What is causing the doctors to act this way? A doctor is aiming more at generating revenue for the hospital he/she works. A doctor is required to cover xyz amount of patients/cases within abc number of days. They need to handle cases plus also keep track of every tiny detail in a system that is not as simple as hand-written notes but a software that is proprietary to the hospital. Typical patient visits are limited to 10-15 minutes. Beyond that there is a designated nurse to interrupt and alert the doctor about the next set of patients waiting. So they just don't have the time to and they also do not feel the need to because they are paid for the number of cases they handle successfully. They don't expand business or go up their career ladder based on doctor-patient relationship. Unless the importance of communication is established and implemented as part of doctor-patient relationship, this will always be a grey area for many. A simple case: a c-section is to be performed on a pregnant lady on a specific date, early in the morning. The instruction given by her doctor or in most cases the nurse is that she should not eat or drink anything other than water after midnight the previous day until the surgery is performed. What needs to be explained is the 'why' part. I have encountered frustrated people blaming and getting angry at the doctor for starving their wife and child. The real reason I have heard is that during a c-section there is a chance of the food backing up resulting in may be mild vomiting or a severe aspiration. Or the patient could throw up after surgery, resulting in damaging her new stitches. All of these cases are harmful to the patient. A simple 2 minute explanation will make the patient aware. Which the doctors are certainly not interested in doing. So, back to the OP, self-diagnoses are important.