The researchers used a linear segmented regression model to define early virological and immunologic determinants of HIV type 1 disease progression among 22 subjects from the Trinidad Seroconvertor Cohort. The scientists fitted the model to sequential quantitative virus load measurements, and they correlated parameters of virus kinetics during different phases of primary infection with clinical and immunologic end points using Kaplan-Meier estimates and Cox regression.

Ten participants (45 percent) developed AIDS during the study. Individuals who developed AIDS were, on average, 6 years older than those who remained AIDS-free.

Univariate analysis showed progression to AIDS to be associated with the rate of initial HIV clearance, virus load during set point, and CD4+ cell count during steady state. Multivariate analysis showed a rapid rate of initial clearance to be the sole independent predictor of subsequent progression to AIDS, and that rapid initial clearance is associated with a 92 percent reduction in the risk of AIDS. The investigators found that the rate of initial clearance inversely correlated with the number of early symptoms, but that symptoms did not predict subsequent risk of AIDS.

"Among a subset of patients, rapid clearance of plasma HIV-1 after peak viremia is associated with lower viral set point, prolonged virus suppression before loss of virologic control, and decreased risk of AIDS," the researchers concluded. "These findings are consistent with the hypothesis that effective immune responses during the earliest phase of infection are important determinants of the subsequent natural history."

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