Spirituality and Religiosity in End-of-Life Decision-Making in Intensive Care Units: A Systematic Review of Preferences, Ethical Framing, and Meaning-Making.

End-of-life decision-making in intensive care units (ICUs) is a complex and ethically challenging process shaped not only by clinical factors but also by patients' values, cultural contexts, and spiritual or religious beliefs. Although spirituality and religiosity are increasingly recognized as influential in decisions regarding life-sustaining treatment, their role has not been comprehensively synthesized within ICU settings. This systematic review, conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, examined the influence of spirituality and religiosity on end-of-life decision-making among adult ICU patients, surrogate decision-makers, and healthcare professionals. Electronic searches of PubMed/MEDLINE, Scopus, and Web of Science identified eligible quantitative, qualitative, and mixed-methods studies, and findings were synthesized narratively because of methodological heterogeneity. Eight studies met the inclusion criteria. Overall, higher levels of religiosity were consistently associated with a stronger preference for aggressive life-prolonging interventions and a lower likelihood of treatment limitation. Spiritual and religious beliefs also influenced clinicians' ethical perspectives, particularly regarding the distinction between withholding and withdrawing life-sustaining treatments, while playing a central role in surrogate decision-making by shaping interpretations of illness, hope, and acceptable care. At the same time, spirituality demonstrated a multidimensional role, facilitating acceptance of death, promoting support for palliative care in some contexts, and contributing to meaning-making during the end-of-life process. Cultural and contextual factors moderated these relationships, and the provision of spiritual care by healthcare professionals was associated with less aggressive end-of-life care. These findings indicate that spirituality and religiosity exert a substantial yet context-dependent influence on end-of-life decision-making in ICUs. Integrating spiritual assessment and culturally sensitive spiritual care into routine clinical practice may enhance shared decision-making and improve alignment between treatment decisions and patients' values, preferences, and goals of care.