EARLY BIOPSY VERSUS EMPIRIC TREATMENT WITH DELAYED BIOPSY OF NONRESPONDERS IN SUSPECTED HIV-ASSOCIATED CEREBRAL TOXOPLASMOSIS - A DECISION-ANALYSIS

Objective: To construct and evaluate a decision analytic model of prop osed management strategies for HIV-infected patients presenting with c erebral mass lesions, radiographically compatible with toxoplasmosis, lymphoma, or other etiologies, assuming knowledge of Toxoplasma antibo dy status in serum. Methods: Using decision analysis, we evaluated two management strategies, for patients found to be either Toxoplasma-ser opositive or -negative, for whom an initial choice was made for early brain biopsy (EB) or for empiric therapy with delayed biopsy (ETDB) of non-responders. The outcome to be optimized was the percentage of pat ients alive at 12 months. Model variables included predictive value of toxoplasmosis serology, probabilities of treatment response and death within 14-21 days conditional on correct diagnosis, probability of op erative death, probabilities of non-diagnostic brain biopsy conditiona l both on correct diagnosis and prior treatment. Results: One and two- way sensitivity analyses, by Toxoplasma serostatus, led to the followi ng conclusions (1) for Toxoplasma-seropositive patients, ETDB gives ne arly equivalent outcomes to EB of all patients; (2) for Toxoplasma-ser onegative patients, although both strategies have equivalent outcomes under baseline assumptions, EB is preferred if there are even small su rvival advantages for early versus delayed diagnosis of lymphoma or ot her conditions, or if risk of death within 14-21 days of ET exceeds 10 % when correct diagnosis is not toxoplasmosis. Conclusion: Under plaus ible assumptions, Toxoplasma-seronegative patients will benefit from a n early biopsy strategy.