Disease progression in patients with virological suppression in response to HAART is associated with the degree of immunological response

OBJECTIVE: To determine if immunological response is associated with disease progression in patients with virological suppression after initiating HAART. DESIGN: A cohort study of 1084 treatment-naive participants in the British Columbia HIV/AIDS Drug Treatment Program who had achieved viral loads < 500 copies/ml at 3-9 months after initiating triple-drug therapy. METHODS: Cox proportional hazards was used to model the association with disease progression of baseline variables, change in CD4 cell counts and CD4 cell count strata at 6 months. Logistic regression analysis was used to examine associations with two definitions of poor immunological response. RESULTS: Patients were followed for a median of 51.4 months. In univariate analyses, increases in CD4 cell counts of < 25 cells/microl and absolute CD4 cell counts of < 200 cells/microl were associated with an increased risk of death or new AIDS events. Two mulitivariate models, one including baseline CD4 cell count and change in CD4 cell count from baseline and the other including only absolute CD4 cell counts at 6 months, were found to predict disease progression in this setting. Increases in CD4 cell count of < 25 cells/microl were associated with increasing age and inversely associated with low baseline CD4 cell counts, high baseline viral loads and good adherence to therapy. CD4 cell counts of < 200 cells/microl at 6 months were associated with low baseline CD4 cell counts and having AIDS at baseline. CONCLUSION: Patients with virological suppression are still at risk for HIV disease progression if adequate immunological responses are not achieved.