A 45-year-old female healthcare worker presents to the occupational health clinic for routine screening. A research consortium is currently analyzing the efficacy of a new serum assay for detecting latent tuberculosis infection at this facility. In a recent validation cohort, the assay was administered to individuals with confirmed latent tuberculosis and individuals who are definitively uninfected. The assay yielded a positive result in of the infected individuals and in of the uninfected individuals.
Based on these validation study results, what is the positive likelihood ratio of this new serum assay?
Answer: 17
Answer
17
The positive likelihood ratio (LR+) is calculated as Sensitivity divided by (1 - Specificity). In this study, the sensitivity is () and the false positive rate (1 - Specificity) is (). Dividing by yields an LR+ of . This means a positive test result is 17 times more likely to be seen in someone with latent tuberculosis than in someone without it.
Step-by-Step Solution
Key Concept
Calculation of Positive Likelihood Ratio (LR+) from raw clinical validation data.