The investigators sought to estimate how much of the person-to-person variation in the rate of CD4 cell loss could be accounted for on the basis of each patient's initial viral load, in an attempt to reproduce more closely the situation that a physician would encounter in clinical practice, where a patient presents with an initial set of laboratory results and the clinician must try to predict how quickly that person's CD4 cell count will reach the danger level at which treatment for HIV becomes most critical. Current clinical practice, based on previous work from other groups, is to focus on both the current CD4 count and the viral load to estimate how rapidly a person's CD4 cell count will decrease. This approach is based on comparisons of the average rate of CD4 cell loss among groups of patients with roughly similar viral loads, which indicate that generally speaking, patients with higher viral loads will tend to experience more rapid CD4 cell loss than patients with lower viral loads. Until now, however, there had been no attempt to quantify how well this observation held when considering the estimated rate of CD4 cell loss for each individual patient.
Using sophisticated statistical modeling, the researchers found that only 4-6% of a
Source:University Hospitals of Cleveland