If the cutoff point in a diagnostic test is moved from point B to C, what is a likely outcome?

• A. Fewer patients diagnosed as infected
• B. Less specificity in the test results
• C. More patients falsely identified as healthy
• D. More patients will be incorrectly diagnosed as being infected

Answer: (D)

Shifting the cutoff point in a diagnostic test from one value to a lower value will likely increase the number of individuals who test positive, which results in more patients being incorrectly diagnosed as infected. This happens because a lower cutoff increases sensitivity; thus, more true positives (actual cases of the disease) may be detected, but it also raises the risk of false positives among individuals who are not truly infected.

This adjustment in the cutoff may create a situation where healthy patients are misclassified as infected, leading to potential overdiagnosis. In this context, the outcome has implications for patient management and public health, as it may result in unnecessary treatments or further testing for those who, under the stricter criterion (point B), would not have been classified as infected.

While the other outcomes mention changes in specificity or fewer patients diagnosed as infected, they do not accurately reflect the consequences of moving the cutoff point down. Lowering the cutoff typically results in increased identification of cases, even if they are false. Hence, this movement in the cutoff is directly related to the potential for incorrectly diagnosing more individuals as having the infection.