Relying on a CD4 count as a marker of potential HIV infection in untested individuals may be misleading, according to intensive care clinicians at the University of Pennsylvania.
They reviewed 53 HIV-negative patients admitted to their intensive care unit during 1996 and 1997, and found that 17% had CD4 counts below 200, the level normally associated with a diagnosis of AIDS.
The mean CD4 count was 510, just 10 cells above the recommended threshold for starting antiretroviral therapy in the United States. CD4+/CD8+ ratios were normal, unlike in cases of HIV-related immunosuppression.
Acute illnesses included severe infections (although not opportunistic infections classified as AIDS-defining), end-stage liver disease, drug overdose, pancreatitis and gastrointestinal bleeding. The median age of participants was 56. A CD4 count below 200 cells on admission was associated with a 2.4-fold increased risk of death.
The results led the University of Pennsylvania team to conclude that "CD4 count should not be relied on for a presumptive diagnosis of HIV in lieu of consent for serologic testing".
Reference
Aldrich J et al. The effect of acute severe illness on CD+ lymphocyte counts in nonimmunocompromised patients. Archives of Internal Medicine 160 (5), 2000