Sensitivity, specificity, positive and negative predictive values: diagnosing purple mange.

PURPOSE

To shed light on several epidemiological terms for better understanding of diagnostic testing measures by using a mythical condition, "purple mange."

DATA SOURCES

Scientific literature related to epidemiology and statistical tests.

CONCLUSIONS

Nurse practitioners (NPs) use the concepts of sensitivity (SEN), specificity (SPEC), positive predictive value (PPV), and negative predictive value (NPV) daily in primary care and specialty areas. In addition, PPV and NPV vary with the prevalence of a condition. At times, NPs misunderstand the meaning of these terms.

IMPLICATIONS FOR PRACTICE

In order to develop appropriate treatment plans, an understanding of the concepts of SEN, SPEC, PPV, and NPV is important for interpreting test results. The authors have used this mythical condition purple mange as a teaching tool for NP students.