Matters Arising: Immortal time bias in the analysis of drug prescription trajectories

Aguayo-Orozco et al. [1] report survival differences in patients taking renin-angiotensin system inhibitors depending on the drug prescription trajectories identified through Danish healthcare registries. They found that changing from an initial prescription of an ACE (angiotensin-converting enzyme) inhibitor to an angiotensin receptor blocker (ARB) and vice versa conferred a survival benefit compared to no change using standard statistical tools for survival analysis. They replicated this finding in data from the UK Biobank and concluded that their results may be important when updating treatment guidelines