Predictive value of Toxoplasma gondii antibody titres on the occurrence of toxoplasmic encephalitis in HIV-infected patients. ANRS 005/ACTG 154 Trial Group.
OBJECTIVE
To study the predictive value of anti-Toxoplasma gondii antibody titres for the occurrence of toxoplasmic encephalitis (TE) in HIV-infected patients.


METHODS
Data from the placebo arm of a trial of primary prophylaxis for TE (ANRS 005/ACTG 154) were analysed. Patients included had CD4+ cell counts < 200 x 10(6)/l and a positive Toxoplasma serology. Immunoglobulin (Ig) G and IgM Toxoplasma antibody titres at entry were retrospectively determined by enzyme-linked immunosorbent assay and agglutination on serum samples in a single laboratory. Incidence of TE was estimated by Kaplan-Meier method and a Cox model was used to study the predictive value of antibody titres, adjusted for other covariates.


RESULTS
All 164 patients studied were positive for IgG antibodies and one had IgM antibodies. After a mean follow-up of 16 months, 31 cases of TE were documented. One-year incidence of TE was significantly higher in patients with IgG titres > or = 150 IU/ml (23.7%) than in patients with titres < 150 IU/ml (7.7%; relative risk, 3.1; P < 0.003). IgG titres remained significantly associated with the occurrence of TE (relative risk, 3.3; P < 0.005) in the Cox model. Predictive value of IgG titres did not differ according to baseline CD4+ cell counts.


CONCLUSIONS
In patients with CD4+ cell counts < 200 x 10(6)/l, IgG anti-Toxoplasma antibody titre is a prognostic factor of occurrence of TE, with a higher risk for titres > or = 150 IU/ml. This finding should reinforce the recommendation of specific prophylaxis in these patients.
Derouin
F
F
Laboratory of Parasitology, Saint-Louis Hospital, Paris, France.
Leport
C
C
Pueyo
S
S
Morlat
P
P
Letrillart
B
B
Chêne
G
G
Ecobichon
J L
JL
Luft
B
B
Aubertin
J
J
Hafner
R
R
Vildé
J L
JL
Salamon
R
R
D017088:AIDS-Related Opportunistic Infections / Q000097:blood / Q000276:immunology*; D000293:Adolescent; D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000981:Antiprotozoal Agents / Q000627:therapeutic use; D018791:CD4 Lymphocyte Count; D004311:Double-Blind Method; D004660:Encephalitis / Q000097:blood / Q000188:drug therapy / Q000276:immunology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D011237:Predictive Value of Tests; D011336:Probability; D011739:Pyrimethamine / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic; D012189:Retrospective Studies; D014122:Toxoplasma / Q000276:immunology*; D016781:Toxoplasmosis, Cerebral / Q000097:blood / Q000188:drug therapy / Q000276:immunology*
D000913:Antibodies, Protozoan; D000981:Antiprotozoal Agents; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011739:Pyrimethamine