INTRACRANIAL MASS LESIONS IN ACQUIRED-IMMUNODEFICIENCY-SYNDROME - USING DECISION-ANALYSIS TO DETERMINE THE EFFECTIVENESS OF STEREOTAXIC BRAIN BIOPSY

We studied the effectiveness of performing a stereotactic brain biopsy in the individual with acquired immunodeficiency syndrome (AIDS) and an intracranial mass lesion who failed 2 weeks of antitoxoplasmosis th erapy. We used a decision analysis to compare two different treatment strategies: biopsy and no biopsy. The analysis estimates the average l ife expectancy for each choice and investigates the sensitivity of the se results by varying parameters within the model. In the base case an alysis (diagnostic yield of biopsy, 0.89; operative mortality, 0.015; life expectancy of lymphoma untreated and treated, 42 and 120 days), t he life expectancy of the biopsy strategy was 98 days compared with 67 days for the no-biopsy strategy, for a net survival benefit of 31 day s. Sensitivity analyses revealed that the life expectancy of the biops y strategy remained greater than the no-biopsy strategy for a wide ran ge of variable specifications. The net survival benefit, however, was sensitive to the diagnostic success rate, the operative mortality, the likelihood of a lymphoma diagnosis, and the life expectancy of patien ts being diagnosed and treated for lymphoma. These data allow AIDS pat ients and physicians to learn more about the potential outcomes of the alternative management strategies when an individual fails to respond to empiric antitoxoplasmosis therapy.