The role of serum cryptococcal antigen screening for the early diagnosis of cryptococcosis in HIV-infected patients with different ranges of CD4 cell counts.

OBJECTIVE: To determine the role of serum cryptococcal antigen (SCA) for the screening of cryptococcosis in HIV-infected patients with different ranges of CD4 cell counts.

METHODS: A retrospective cohort study was conducted in antiretroviral-naïve HIV-infected patients who had no symptom and had been screened with SCA in a tertiary-care hospital. Prevalence of positive SCA at different ranges of CD4 cell counts, risk factor of positive SCA, and incidence of cryptococcosis during one-year follow-up period after negative SCA were determined.

RESULTS: There were 131 patients with a mean age of 38.5 years; 61.8% were male. Median (range) CD4 was 62 (3-590) cells/mm(3). The overall prevalence of positive SCA was 9.2%. This prevalence in patients with CD4 < 100, 100-199, and >or=200 cells/mm(3) were 12.9%, 3.6%, and 0%, respectively (P = 0.041). In multivariate analysis, CD4 < 100 cells/mm(3) was associated with positive SCA (OR = 6.69; 95% CI, 1.03-23.56). Four (33.3%) of 12 patients with positive SCA had cryptococcosis whereas one (0.8%) of 119 patients with negative SCA developed meningitis at one-year follow-up.

CONCLUSIONS: SCA screening has a substantial role for the early detection of cryptococcal infection in HIV-infected patients with low CD4 cell counts. Routine screening with SCA should be performed in patients with CD4 < 100 cells/mm(3).