Accounting for length of hospital stay in regression models in clinical epidemiology

A further issue is that discharge and death are competing events for hospital‐acquired infections. After discussing the limitations of logistic regression adjusted for length of stay in this setting, we compare this approach with appropriate analyses incorporating competing risks and with an illness–death model with hospital‐acquired infection as an intermediate event. The cumulative incidence function, cause‐specific hazard ratios, and subdistribution hazard ratios are considered as reference measures. Real‐life and simulated data are used to demonstrate biases and limitations associated with logistic regression adjusted for length of stay. We conclude that logistic regression adjusted for length of stay should not be used when investigating hospital‐acquired infections and that appropriate methods involving the use of multistate models should be used to capture the time dependency in time‐to‐event settings, especially in the presence of competing events.