Fig. 1. Assignment of patient-days to case and control groups. IHCA events were assigned using CPR codes in prescription records, categorizing 1–3 days before CPR as cases and ≥4 days before cardiopulmonary resuscitation or all days for patients without CPR as controls. Days of and after CPR were excluded from the modeling dataset.
Abbreviations: IHCA, in-hospital cardiac arrest; CPR, cardiopulmonary resuscitation.

Ann Lab Med 2025;45:209~217 https://doi.org/10.3343/alm.2024.0315