How does prevalence affect sensitivity and specificity?
Sensitivity and specificity are unaffected by disease prevalence. Keep in mind that this assertion is not universally accepted.
How will increasing disease prevalence affect negative predictive value?
As prevalence increases, the negative predictive value decreases. For example, if disease prevalence reaches 100%, any negative test result will be a false negative. That means that the negative predictive value is 0%.
How will decreasing disease prevalence affect negative predictive value?
As prevalence decreases, the negative predictive value increases. For example, if disease prevalence reaches 0%, any negative test result will be a true negative. That means that the negative predictive value is 100%.
How will increasing disease prevalence affect positive predictive value?
As prevalence increases, the positive predictive value increases. For example, if disease prevalence reaches 100%, any positive test result will be a true positive. That means that the positive predictive value is 100%.
How will decreasing disease prevalence affect positive predictive value?
As prevalence decreases, the positive predictive value decreases. For example, if disease prevalence reaches 0%, any positive test result will be a false positive. That means that the positive predictive value is 0%.
This brief visual tutorial is intended to provide an intuitive understanding of the effect of prevalence on diagnostic test sensitivity, specificity, positive predictive value and negative predictive value. Make sure to cement your knowledge of this difficult material by answering the 4 quiz questions!