Study objectives: To assess the potential use of
peripheral blood CD4 + T-lymphocyte counts (CD4 + counts) as a
clinically useful biological marker to identify specific
immunocompromised patients (without HIV infection) at high risk for
Pneumocystis carinii pneumonia (PCP).
Design: Prospective observational study.
Setting: Three hundred seventy-five-bed tertiary-care urban
referral teaching hospital, and 250-bed community-based referral
Patients: One hundred seventy-one
consecutive confirmed HIV-seronegative hospitalized and ambulatory
adults, including 22 patients with active PCP, 8 patients with
bacterial pneumonia, 24 persons in two groups considered at high
clinical risk, 38 persons in two groups considered at low or undefined
risk, and 79 persons in four groups considered not at risk for PCP
(including healthy individuals).
results: Compared to counts in healthy individuals, median
CD4 + counts were significantly decreased in patients with active PCP
(61 cells/μL vs 832 cells/μL; p = 0.001) where 91% of
patients had a CD4 + count < 300 cells/μL at the time of PCP
diagnosis. Median CD4 + counts were also reduced in the high clinical
risk groups of recent organ transplant recipients (117 cells/μL;
p = 0.007), 64% with < 300 cells/μL, and patients receiving
chemotherapy (221 cells/μL; p < 0.01), 80% with < 300
cells/μL. For the low or undefined clinical risk groups, the median
CD4 + counts were not significantly reduced, although 39 to 46% of
individuals receiving long-term corticosteroid therapy (alone or in
combination with other agents) had CD4 + counts < 300 cells/μL.
Median CD4 + counts in individuals considered not at risk for PCP
were similar to those in healthy subjects. Compared to counts in
patients with active PCP, median CD4 + counts were significantly
higher in bacterial pneumonia patients (486 cells/μL; p < 0.05),
but similar to those in healthy subjects.
Conclusions: These data suggest that for
immunosuppressed persons without HIV infection (especially in low or
undefined PCP risk groups), CD4 + counts may be a useful clinical
marker to identify specific individuals at particularly high clinical
risk for PCP and may help to guide