Context: The number of older adults experiencing traumatic injuries admitted to intensive care units is growing. Injured older adults are more likely to experience complications and unplanned ICU readmissions. There is limited knowledge about the drivers of code status decisions in older adults experiencing unplanned ICU readmissions. Objectives: To examine the determinants of code status designation in older trauma patients readmitted to an ICU. Methods: This was a retrospective study of patients aged 65 and older readmitted to a Level I trauma center ICU between 2018 and 2020. Code status was examined before and after the first unplanned ICU readmission. A thematic framework was developed to classify reasons for code status designation. Results: 105 patients admitted to a trauma ICU had unplanned ICU readmission. 52.3% of patients remained full code after ICU readmission while 25.7% changed code status to DNR. The most common reason for changing code status from full code to DNR was reaching an understanding of severity of illness (55.6%). Conclusion: Over a quarter of patients changed their code status from full code to DNR after an unplanned ICU readmission. Frail older adults (Clinical Frailty Scale > 4) and patients aged 80 and older were more likely to change their code status from full code to DNR after an unplanned ICU readmission. The results highlight the importance of communication of illness severity, particularly in frail older adults aged 80 and older to guide decision making in the ICU.