We developed a model to predict BD based on a relatively large population of OHCA patients admitted to our hospital between 2006 and 2018. This was done through creating a logistic regression model based on variables that were easily available after ED arrival. The predictability of BD was accurate, and internal validation yielded an appropriate optimism value. We successfully predicted BD using the OHCA-BD score.
Since the brain is the organ that is most susceptible to hypoxia and inadequate perfusion, OHCA contributes enormously to BD. The rate of organ donation from BD patients following OHCA was reported to be 5.4% in a single-centre study from the United Kingdom , which is not high. Certainly, coordination of organ donation through the decedent’s family is essential for organ donation from BD patients because the refusal rate for organ donation remains high. However, in many cases of OHCA, circulation is refractory, and the patient dies without confirmation of BD or fails to be diagnosed with BD. Furthermore, withdrawing life-sustaining therapy because of perceived poor neurological prognosis is the main cause of hospital death after OHCA [15, 16]. It should be noted that our hospital does not make early decisions to withdraw mechanical, ventilated or organ-perfusion support. Therefore, among patients with a poor neurological prognosis in our retrospective cohort, we could distinguish between patients who developed BD and those who died without developing BD, as in the study by Galbois et al. . We have the same concepts and rules, which leads to lengths of stay in which patients proceed towards BD. Therefore, our intensive care practice did not introduce bias by preventing BD development.
According to the demographic data, there are specific tendencies in BD patients. Younger age is an independent predictor of BD. This may be because the brain of a younger person occupies less space in the cranium than those of older individuals. Hematomas and multiple hemispheric lesions with oedema contribute to brain herniation, which leads to BD due to compression of the brainstem. Furthermore, older patients tend to die by circulatory collapse, which avoids progression towards BD. OHCA due to cerebrovascular disease corresponded most strongly with BD in terms of aetiology. However, other parameters of tissue hypoperfusion, such as lactate, pH, and low-flow time, were indicators of poor outcomes but not specific indicators of BD.
Ahmad et al. introduced the NULL-PLEASE score, which predicts poor neurological outcomes in OHCA patients . However, the NULL-PLEASE score could not predict the development of BD in the present study. Patients with poor neurological outcomes predicted by the NULL-PLEASE score include patients in a vegetative state and those who died without developing BD. Therefore, to predict progression to BD, a specific prediction scoring model is needed.
Organ donation is a stressful and difficult end-of-life decision causing anxiety, depression, and decreased quality of life among family members of the deceased donor . The family needs to fully understand that BD means the death of their loved one and that we need consent from the family for organ donation . This process is also ethically and emotionally challenging for the physicians involved . We may reduce this burden by objective assessment using a predictive score. Taking these concerns into account, the early detection of BD is merely one step aimed toward respecting the patient’s and family’s decisions.
Limitations of this study include the single-centre design, possible selection bias, and confounding by unknown or unmeasured variables. We may also have bias in treatment for OHCA patients. Although bootstrapping is a strong tool for statistical internal validation, it cannot avoid overlapping of patients selected for each dataset. Furthermore, we did not perform external validation with the present score. Prospective observational studies are needed for external validation.