A PROSPECTIVE-STUDY OF CRITERIA FOR THE DIAGNOSIS OF TOXOPLASMIC ENCEPHALITIS IN 186 AIDS PATIENTS

Objective: To define the factors associated with diagnosis of toxoplas mic encephalitis (TE) in AIDS patients; and to establish a rational pr ocedure for the clinician faced with a decision concerning empiric ant itoxoplasma therapy. Design: A 15-month prospective multicentre cohort study in France. Methods: One hundred and eighty-six consecutive HIV- positive inpatients undergoing empiric antitoxoplasma therapy for a fi rst episode of presumed TE were monitored. The clinician's initial est imation of the probability of response to antitoxoplasma therapy was r ecorded. In addition, a validation committee classified cases as TE or non-TE. Results: Among the 186 patients, the following variables were significantly more frequent in TE (n = 113)than non-TE (n = 73) patie nts: fever (59% versus 40%), headache (55% versus 33%), seizures (22% versus 11%), suggestive lesions on the brain scan (98% versus 76%), po sitive Toxoplasma serology (97% Versus 71%). Median CD4+ lymphocyte co unt was significantly higher in TE than in non-TE (27 x 10(6)/l versus 11 x 10(6)/l). The rate of TE in patients on systemic antiprotozoal p rophylaxis at entry was 43% as compared with 75% in patients without p revious prophylaxis. Pre-therapy estimation of response to empiric the rapy was highly correlated with final diagnosis. Multivariate logistic regression analysis showed that the following variables contributed i ndependently to the diagnosis of TE: clinician's estimation of respons e to treatment at entry > 75%; absence of systemic antiprotozoal proph ylaxis; seizures; headache; suggestive lesions on CT or MRI brain scan ; and positive Toxoplasma serology. Conclusions: A linear logistic mod el is proposed which uses significant variables, which are readily ava ilable. This model gives good accuracy to classify suspected cases of TE.