• combination treatment;
  • HIV;
  • observational database;
  • rates

Objective To estimate the rate of combination antiretroviral treatment change and factors associated with combination antiretroviral treatment change among patients recruited in the Australian HIV Observational Database (AHOD).

Methods Analyses were based on patients in the AHOD who had commenced combination antiretroviral treatment after 1 January 1997. Combination antiretroviral treatment change was defined as the addition or change of at least one antiretroviral drug. A random-effect Poisson regression model was used to assess factors associated with increased rates of combination antiretroviral treatment change.

Results A total of 596 patients in the AHOD were included in the analysis, with a median follow-up of 2.3 years. The overall rate of antiretroviral treatment change in this group was 0.45 combinations per year. In a multivariate analysis, a low CD4 count (< 200 cells/μL) at baseline was associated with an increased rate of treatment change [rate ratio (RR)=1.43; 95% confidence interval (CI), 1.13, 1.80; P=0.003)]. Combinations including a nonnucleoside reverse transcriptase inhibitor were also associated with slower rates of change than treatment combinations including a protease inhibitor (RR=0.64, 95% CI, 0.51, 0.80, P < 0.001).

Conclusion Initiating combination antiretroviral at a CD4 cell count < 200 cells/μL may be associated with poorer patient outcomes. However, the possibility that clinician or patient concerns about low immunological status led to faster rates of treatment change in this group cannot be discounted.