In clinical practice, the "CAGE" questionnaire is used to screen patients for alcohol use disorder (AUD). When a patient replies with 2 out of 4 positive responses to the "CAGE" questions, the test is considered to be positive for AUD. If this criterion is changed so that 3 out of 4 positive responses to the "CAGE" questions label the patient as having AUD, what is the effect on the sensitivity and specificity of this test?

Question

In clinical practice, the "CAGE" questionnaire is used to screen patients for alcohol use disorder (AUD).  When a patient replies with 2 out of 4 positive responses to the "CAGE" questions, the test is considered to be positive for AUD.  If this criterion is changed so that 3 out of 4 positive responses to the "CAGE" questions label the patient as having AUD, what is the effect on the sensitivity and specificity of this test?

Quizplus · Accepted Answer

11ec25c8_d23d_9208_bc81_f5d56ecfed32_MD0003_00 The ability to correctly identify patients with disease as positive is the sensitivity of the test, calculated as the number of true positives (TP) divided by the total number of TP and false negatives (FN): Sensitivity = TP / (TP + FN). The ability to correctly identify patients without disease as negative is the specificity of the test, calculated as the number of true negatives (TN) divided by the total number of TN and false positives (FP): Specificity = TN / (TN + FP). Raising the cut-off point of a test will increase its specificity and decrease its sensitivity. In this particular vignette, increasing the number of questions for a patient to be labelled as having alcohol use disorder will result in fewer people being identified as such. Consequently, FPs and TPs will decrease, while FNs and TNs will increase. Educational objective: Raising the cut-off point (eg, increasing the inclusion criteria) of a screening test results in an increase in specificity and decrease in sensitivity.

In Clinical Practice, the "CAGE" Questionnaire Is Used to Screen