CD4s and OI Risk: The Absolute Count or the Percent?

Both absolute CD4-cell count and CD4 percent are currently considered when initiating prophylactic therapy for opportunistic infections (OIs). These two values are usually well correlated, such that a patient with an absolute CD4 T-cell count of 200 cells/mm³ will have a CD4 percent of approximately 14%. When discordant results do occur, however, it is unclear which measure is the best predictor of short-term risk for the development of an OI. In this observational, longitudinal, cohort study, using data from the Johns Hopkins AIDS Service clinical database, the rate of discordance between absolute CD4 count and CD4 percentage was determined in 15,736 CD4 count/CD4 percent pairs from 2185 patients (mean age, 37.6 years) who were followed fr…