The predictive value of diagnostic procedures

Nurses are in an ideal position to answer clients' questions regarding the necessity of diagnostic tests and clarification of test results. A perfect test would always be positive in the presence of disease and negative in the absence of disease. However, false-negative or false-positive results are a reality and must be considered as the clinician strives for accuracy in diagnostic procedures. Understanding predictive value enables the nurse to discuss the rationale, usefulness and limitations of tests currently used to assess disease, disease activity and to guide therapy.