INTRODUCTION: The corona virus disease 19 (COVID-19) pandemic has presented a global health challenge, and several consecutive variants of the severe acute respiratory syndrome-corona virus-2 (SARS-CoV-2) virus have been dominant. Previous studies highlighted decreased mortality rates during the predominance of the omicron variant
however, severely immunocompromised individuals remained at high risk due to limited vaccine response. This study aims to compare mortality rates during the omicron period between immunocompromised and non-immunocompromised patients in intensive care units (ICUs) in The Netherlands. METHODS: Utilizing data from the Dutch National Intensive Care Evaluation (NICE) registry, this study analyzed ICU admissions due to COVID-19 from February 2022 to December 2023. Patients were categorized as immunocompromised based on recorded immunologic insufficiencies or associated conditions. A historical cohort of viral pneumonia patients from 2017 to 2019 was used for comparison. Logistic regression analyses, adjusted for age, gender, body-mass index (BMI), and acute physiology and chronic health evaluation IV (APACHE-IV) mortality risk, compared in-hospital and ICU mortality and length of stay between groups. A sensitivity analysis excluded early omicron period admissions to assess the consistency of findings. RESULTS: Among 1491 patients admitted to the ICU due to COVID-19, 29.5% were immunocompromised, showing significantly higher in-hospital adjusted odds ratio (OR CONCLUSION: Immunocompromised patients admitted to the ICU due to COVID-19 during the omicron period had higher mortality than non-immunocompromised patients. Additionally, immunocompromised patients with COVID-19 had higher mortality than immunocompromised patients with other viral pneumonias. Our results provide additional evidence that COVID-19 is still a significant health concern to immunocompromised individuals, which warrants specific and effective measures to protect this vulnerable group.