Diagnostic workup strategies for patients with HIV-related chronic diarrhea. What is the end result?

The intensity of diagnostic workup of patients with human immunodeficiency virus (HIV)-related chronic diarrhea is controversial. In the ideal setting in which an enteric pathogen is detected with minimal evaluation (stool tests) and in which specific treatment clears the diarrhea, eradicates the pathogen, and improves the patient's quality of life, the need for diagnostic workup is clear. However, problems frequently occur in the evaluation and treatment of patients that preclude such a straightforward approach. They are (a) failure to detect enteric pathogens; (b) detection of organisms of uncertain significance; (c) lack of effective treatment; (d) the presence of a severe coexisting illness that is the major determinant of the patient's outcome; and (e) lack of evidence that detecting enteric pathogens leads to improvement in broad patient outcomes, such as quality of life. I discuss these problems and examine the two opposing diagnostic workup strategies--minimal and intensive evaluation--that have been advocated. My main conclusion is that both approaches fall short, and that clinicians lack the information needed to guide clinical decision making. I urge investigators to analyze the full effects of alternative diagnostic interventions on broad patient outcomes so that clinical guidelines can be developed to assist the evaluation of patients.