Left-digit bias in out-hospital cardiac arrest: The JCS-ReSS study.

Introduction: The left-digit bias (LDB), a numerical-related cognitive bias, not only potentially influences decision-making among the general public but also that of medical practitioners. Few studies have investigated its role in out-of-hospital cardiac arrest (OHCA).

Methods: We retrospectively included all consecutive patients with OHCA witnessed by family members registered in the All-Japan Utstein Registry of the Fire and Disaster Management Agency between January 1, 2005, and December 31, 2020. Target outcomes were the percentage of bystander cardiopulmonary resuscitation (BCPR) performed by family members or paramedics and the percentage of prehospital physician-staffed advanced cardiac life support (ACLS). Using a nonparametric regression discontinuity methodology, we examined whether a significant change occurred in the percentages of BCPR and ACLS at the age thresholds of 60, 70, 80, and 90 years, which would indicate the presence of LDB.

Results: Of the 1,930,273 OHCA cases in the All-Japan Utstein Registry, 384,200 (19.9%) cases witnessed by family members were analyzed. The mean age was 75.8 years (±SD 13.7), with 38.0% (n = 146,137) female. We identified no discontinuities in the percentages of chest compressions, mouth-to-mouth ventilation, or automated external defibrillator (AED) usage by family members for the age thresholds of 60, 70, 80, and 90 years. Moreover, no discontinuities existed in the percentages of chest compressions, advanced airway management, and AED usage by paramedics or prehospital ACLS by physicians for any of the age thresholds.

Conclusions: In conclusion, our study did not find any evidence that age-related LDB affects medical decision-making in patients with OHCA.