Regarding: Time to initiation of extracorporeal membrane oxygenation in conventional cardiopulmonary resuscitation affects the patient survival prognosis

The article by Sim et al. [1] in the Journal of Internal Medicine emphasized the critical role of timely ECMO application in optimizing outcomes for patients undergoing ECPR. While recognizing the careful work and valuable contributions of this study, there are some constructive suggestions for future advancement.

First, although the study accounted for various adjustment factors, it may have overlooked some potential influencing variables, such as patient comorbidities or changes in treatment protocols following ECMO initiation. These factors could affect the reliability and validity of the study's results [2].

Second, in the study, the Cox proportional hazards assumption may be violated for several reasons: time dependency: If the effect of ECMO initiation on survival varies over time, it breaches the assumption that hazard ratios remain constant throughout the study period; sample heterogeneity: Variability in patient characteristics within the sample may cause fluctuations in hazard ratios, thus violating the proportionality assumption; lack of testing: Without assessing the proportional hazards assumption using methods like Schoenfeld residuals, undetected violations could compromise the model's validity. Addressing these issues is crucial for ensuring the robustness and accuracy of the Cox regression analysis [3].

Third, the study primarily focuses on short-term outcomes (e.g., 30 days, 90 days, and 6 months), and there may be insufficient assessment of long-term survival and quality of life [4]. It is recommended that future research includes extended follow-up periods to obtain more comprehensive prognostic information.

In conclusion, the results of this study emphasize that the early initiation of ECMO during ECPR significantly improves short- and long-term overall survival outcomes. It highlights the need for prospective, multi-center research, long-term follow-up, standardized protocols, and optimization of procedures to improve clinical practices and patient survival.

Xiao Liu: Conceptualization; methodology; writing—original draft; validation. Bo Liu: Writing—review and editing. Minli Yang: Methodology; supervision. Liu Yang: Methodology; writing—review and editing. Jun Wang: Writing—review and editing; supervision.

The authors declare no conflicts of interest.