The generalized Nelson--Aalen estimator by inverse probability of treatment weighting

Inverse probability of treatment weighting (IPTW) has been well applied in causal inference. For time-to-event outcomes, IPTW is performed by weighting the event counting process and at-risk process, resulting in a generalized Nelson--Aalen estimator for population-level hazards. In the presence of competing events, we adopt the counterfactual cumulative incidence of a primary event as the estimated. When the propensity score is estimated, we derive the influence function of the hazard estimator, and then establish the asymptotic property of the incidence estimator. We show that the uncertainty in the estimated propensity score contributes to an additional variation in the IPTW estimator of the cumulative incidence. However, through simulation and real-data application, we find that the additional variation is usually small.