THE EFFECTIVENESS OF INTERVENTIONS ON INCUBATION OF AIDS AS MEASURED BY SECULAR INCREASES WITHIN A POPULATION

Methods are developed to estimate and test for the impact of intervent ion use on a population's survival function (time to AIDS), Each parti cipant's history is divided into J + 1 components: Omega(0) occurring before the intervention is available and Omega(1) to Omega(J) occurrin g later, as the intervention becomes successively more available. Dist ribution free truncated Kaplan-Meier models based on time since exposu re fit separately to the risk sets/outcomes in Omega(0) to Omega(J) di rectly show the changing patterns of survival. Multivariate proportion al hazards models can be used to adjust for covariates. Application of these methods indicates that availability of proven anti-AIDS interve ntions may have delayed time to AIDS by 8 months in an educated HIV-1 infected homosexual cohort with good access to medical care.