Abstract Body

Current guidelines recommend that secondary Toxoplasma gondii prophylaxis can be safely discontinued in HIV-infected patients with suppressed viremia on antiretroviral therapy (ART) and a CD4 cell count >200 cells/mm3. Whether such a policy can be extended to patients with CD4 cell counts between 100-200 cells/mm3 is unknown.

The Collaboration of Observational HIV Epidemiological Research in Europe (COHERE) included data from 10 European cohorts on 1151 HIV-infected patients who developed a toxoplasmic encephalitis (TE) and started ART after 1997. TE was diagnosed on the basis of the 1993 CDC case definition. A relapse was defined as a new TE episode after 4 months of the initial TE. Patient follow-up began at the date of the first TE and ended at the time of first TE relapse, last visit, or death, whichever occurred first. Incidence rates of TE relapses were calculated after stratification by current use of prophylaxis, current CD4 cell count, and current viral load (VL). Multivariate Poisson regression models were used to model incidence rate ratios (IRRs) of TE.

There were 79 TE relapses during 6,030 person-years of follow-up (PYFU). The incidence of TE relapses stratified by current CD4 cell count, detectable or undetectable VL, and use of prophylaxis is shown in the figure. Among patients who had a current CD4 cell count of 100-200 cells/mm3 and an undetectable VL (<400 copies/mL), incidence of TE was 0.9 episodes per 100 PYFU (95% CI, 0.11-3.2; 2 episodes during 224 PYFU) in those receiving T. gondii prophylaxis and 1.9 relapses per 100 PYFU (95% CI, 0.75-3.8; 7 episodes during 376 PYFU), in those who stopped prophylaxis (P=0.349). Among virologically suppressed patients on ART without secondary T. gondii prophylaxis, the incidence of TE in patients with CD4 100-200 was significantly higher than that seen in patients with CD4>200 cells/mm3 (0.5 (95% CI, 0.3-0.8) episodes per 100 PYFU; P=0.002). Doubling CD4 cell count/mm3 (IRR, 0.77; 95% CI, 0.68–0.87; P<.001) was the only TE relapse predictor; whereas detectable VL (IRR, 1.64; 95% CI, 0.92–2.93; P=0.092) and prophylaxis (IRR, 1.00; 95% CI, 0.61–1.64; P=.998) were not predictors.

In suppressed HIV-infected adult patients, secondary prophylaxis against TE can be safely discontinued in patients with CD4 cell counts >200 cells/mm3. Conversely, secondary TE prophylaxis should not be stopped in virologically suppressed patients with CD4 counts of 100-200 cells/mm3