MCAT Verbal Practice by Schnedeker Bryan

Author:Schnedeker, Bryan
Language: eng
Format: epub
Publisher: Next Step Test Preparation Publishing
Published: 2016-03-15T00:00:00+00:00

SECTION 7

53 Questions, 90 Minutes

Use an answer grid from the back of the book to record your answers

Passage 1 (Questions 1 – 5)

Experienced tuberculosis controllers are keenly aware of the discrepancies between the theory and the reality of finding and treating latent tuberculosis infection (LTBI). Although the guidelines about LTBI appear to be straightforward on the surface, in truth the tasks are challenging, and efficiency and effectiveness are difficult to achieve. In this section, we review the general principles that influence the success of your prevention activities.

The success of your prevention activities is governed by three elements that we all need to balance simultaneously in order to have successful public health interventions. These elements are: (1) finding and accurately diagnosing LTBI, (2) determining the urgency of treatment, and (3) completely treating the patients who have LTBI. Problems in any of these three areas will detract from the success of your activities. For example, if you start a project that finds dozens of at-risk patients who have LTBI but none of the patients start or complete treatment, the project does not contribute to tuberculosis prevention. ARPEs give you a broad overview that helps you to find problems and to strike a balance among the three elements.

Finding and accurately diagnosing LTBI depends on the prevalence rate of LTBI in the population that is under consideration. The prevalence rate refers to how common LTBI is, and it is a population characteristic that reflects the tuberculosis history of the population. The prevalence rate controls how many infected individuals you will discover by testing. This is your yield of LTBI. The minimum prevalence rate for a successful strategy is unknown, but you need to take a critical look at the balance of the three elements if you are testing in a population having an LTBI prevalence rate less than 10 percent. The LTBI prevalence rate also influences the accuracy of the tuberculin skin test. This is because the predictive value of a positive test result depends on the prevalence rate. When the prevalence rate is low, the predictive value of a positive result is also low. For example, when the LTBI prevalence rate falls below 10 percent, most of the patients with positive results from the skin test actually will have false-positive results. Therefore, when the prevalence rate of LTBI is low, most of the patients who are being treated for LTBI are actually not at risk for tuberculosis because they do not even have LTBI. This is wasteful of resources and possibly hazardous to the patients.

The urgency of treatment for LTBI patients depends on how likely they are to get sick with active tuberculosis. If the likelihood of active tuberculosis is high, then the urgency of treatment is high. One example is the patients who have been recently exposed to contagious tuberculosis (i.e., contacts). We also worry about patients who have medical problems that change their immune capacity: co-infection with the human immunodeficiency virus (HIV) is a very serious example. The urgency of treatment is relative.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.