WBR0660: Difference between revisions
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{{WBRQuestion | {{WBRQuestion | ||
|QuestionAuthor={{SSK}} (Reviewed by Serge Korjian) | |QuestionAuthor={{SSK}} (Reviewed by Serge Korjian and {{YD}}) | ||
|ExamType=USMLE Step 1 | |ExamType=USMLE Step 1 | ||
|MainCategory=Biostatistics/Epidemiology | |MainCategory=Biostatistics/Epidemiology | ||
| Line 21: | Line 21: | ||
|MainCategory=Biostatistics/Epidemiology | |MainCategory=Biostatistics/Epidemiology | ||
|SubCategory=Gastrointestinal | |SubCategory=Gastrointestinal | ||
|Prompt=A new vaccine is being developed for the prevention of Hepatitis E. In a phase 2 clinical trial, 100 individuals are randomized to receive either the vaccine or | |Prompt=A new vaccine is being developed for the prevention of Hepatitis E. In a phase 2 clinical trial, 100 individuals with negative Hepatitis E IgM and IgG anti-HEV antibodies are randomized to receive either the vaccine or placebo. Out of the 50 patients that received the vaccine, 1 went on to develop Hepatitis E in the 6 month follow-up after the vaccination. In the placebo group, 7 out of 50 patients developed Hepatitis E. What is the number needed to treat for this newly developed vaccine according to the results of this trial? | ||
|Explanation=The number needed to treat refers to the number of patients required to receive a certain treatment for 1 patient to benefit from it. It is usually the inverse of the absolute risk reduction(ARR). The ARR can be calculated as follows: | |Explanation=The number needed to treat refers to the number of patients required to receive a certain treatment for 1 patient to benefit from it. It is usually the inverse of the absolute risk reduction(ARR). The ARR can be calculated as follows: | ||
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|AnswerE=Data insufficient to calculate | |AnswerE=Data insufficient to calculate | ||
|AnswerEExp=Given the equation below, all variables are available to calculate the number needed to treat. | |AnswerEExp=Given the equation below, all variables are available to calculate the number needed to treat. | ||
|EducationalObjectives=The number needed to treat is | |EducationalObjectives=The number needed to treat is represents the inverse of the absolute risk reduction (1/ARR) | ||
|References=First Aid 2014 page 53 | |||
|RightAnswer=C | |RightAnswer=C | ||
|WBRKeyword=Number needed to treat, Absolute risk reduction | |WBRKeyword=Number needed to treat, Absolute risk reduction | ||
|Approved=Yes | |Approved=Yes | ||
}} | }} | ||
Revision as of 16:41, 17 September 2014
| Author | [[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian and Yazan Daaboul, M.D.)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Biostatistics/Epidemiology |
| Sub Category | SubCategory::Gastrointestinal |
| Prompt | [[Prompt::A new vaccine is being developed for the prevention of Hepatitis E. In a phase 2 clinical trial, 100 individuals with negative Hepatitis E IgM and IgG anti-HEV antibodies are randomized to receive either the vaccine or placebo. Out of the 50 patients that received the vaccine, 1 went on to develop Hepatitis E in the 6 month follow-up after the vaccination. In the placebo group, 7 out of 50 patients developed Hepatitis E. What is the number needed to treat for this newly developed vaccine according to the results of this trial?]] |
| Answer A | AnswerA::0.14 |
| Answer A Explanation | AnswerAExp::0.14 is not the number needed to treat |
| Answer B | AnswerB::7.14 |
| Answer B Explanation | AnswerBExp::7.14 is not the number needed to treat |
| Answer C | AnswerC::8.33 |
| Answer C Explanation | AnswerCExp::The number needed to treat in this trial is 8.33 |
| Answer D | AnswerD::300 |
| Answer D Explanation | AnswerDExp::300 is not the number needed to treat |
| Answer E | AnswerE::Data insufficient to calculate |
| Answer E Explanation | AnswerEExp::Given the equation below, all variables are available to calculate the number needed to treat. |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::The number needed to treat refers to the number of patients required to receive a certain treatment for 1 patient to benefit from it. It is usually the inverse of the absolute risk reduction(ARR). The ARR can be calculated as follows:
|
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Number needed to treat, WBRKeyword::Absolute risk reduction |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
