ABSTRACT
Many investigators have contributed statistical methodology toward validating change in CD4 cell count as a surrogate endpoint for clinical outcome in HIV-infected patients. M. G. Hughes et al. outline two methods for showing surrogacy in their seminal paper as: approach 1: this is the within-trial statistical approach of calculating proportion of treatment effect explained by the surrogate and approach 2: across-trial approach: this is the statistical approach of meta-analysis of pooling information from several trials. Hughes et al. evaluated initial changes in CD4 cell count as a surrogate endpoint for clinical outcome in HIV-infected patients. The strength considered relevant is subject to the disease area and to the disease-treatment research stage, with later stages requiring more evidence of strength. The data were previously used by M. D. Daniels and Hughes to assess whether the change in CD4 cell count is a surrogate for time to either development of AIDS or death in drug trials of patients with HIV.
