Use of rapidly generated results in patient management.

The usefulness of a rapid diagnostic test in patient management depends on the sensitivity of the test, the clinical consequences of false-negative or false-positive results, the ease and cost of performance, and the timely availability of results. A test that is sensitive, specific, inexpensive, and rapid is presumed to be useful clinically. However, there has been surprisingly little effort to measure the actual impact of the results on patient care. Since antigen detection for Haemophilus influenzae type b disease has been available for more than a decade, it will be used as a model to illustrate several factors that help determine the benefits, limitations, and pitfalls of antigen detection in the management of patients with serious bacterial infections. Herein we will compare the use of antigen detection in meningitis with that in other Haemophilus influenzae type b diseases. We also will review our experience with the impact of rapid diagnosis on the treatment of bacterial meningitis. Finally, other factors that influence the usefulness of antigen detection on patient care will be explored by comparing the potential consequences of laboratory error on the management of patients with Haemophilus influenzae type b infections with that of management of other kinds of infections, such as streptococcal pharyngitis, sexually transmitted diseases, and viral respiratory infections.