Poor baseline immune function predicts an incomplete immune response to combination antiretroviral treatment despite sustained viral suppression.

Objectives: To determine the prevalence and predictors of an incomplete immune response in patients with sustained viral suppression after starting their first or second combination antiretroviral treatment (cART) regimen. Methods: All patients were recruited to the Australian HIV Observational Database (AHOD) by March 2006. Data were analyzed to assess the prevalence of an incomplete immune response (,350 cells/mL) in the 12–24 months after starting the first or second cART regimen. Factors associated with an incomplete immune response were assessed using logistic regression and time to AIDS/death was assessed using survival analysis. Results: Of the 2493 patients recruited to AHOD by March 2006, 590 were eligible for the analysis. Twenty-eight percent of patients with a baseline CD4 count, 350 cells per microliter had an incomplete immune response 12–24 months after starting their first or second cART regimen. Lower baseline CD4 count before starting the cART regimen was predictive of an incomplete immune response. There was a nonsignificant trend toward faster AIDS or death in incomplete immune responders. Conclusions: An incomplete immune response in patients with sustained viral suppression is associated with poorer immune function before starting cART. Type of cART or individual antiretroviral drug was not associated with an incomplete immune response.