Peripheral T-lymphopenia implicated unfavorable prognosis in patients with critically ill systemic autoimmune rheumatic diseases

Systemic autoimmune rheumatic diseases (SARDs) contain various disease spectrums with complex clinical manifestations. The management of life-threatening SARDs requiring intensive care is a challenge due to the complexity and the lack of rheumatologist support. The first independent rheumatology intensive care unit (Rh-ICU) throughout the China was established in our center after COVID-19 pandemic. We are working to build a more precise prognostic model with an immunology perspective to better understand and manage the special critically ill SARDs. A retrospective study was conducted in the patients admitted into Rh-ICU. The clinical data of Rh-ICU first admission was collected and analyzed. Survival analysis was performed in derivation cohort ( n = 305) and result was verified in validation cohort ( n = 114). Systemic lupus erythematosus (SLE) was the most common disease of Rh-ICU cohort followed by anti-MDA5 dermatomyositis (MDA5 + DM), antisynthetase syndrome, and others. COX analysis identified T-lymphopenia (T-cell < 700 cells/ul) and APACHE-II score were independent prognostic factors for 28-day ICU mortality. Moreover, T-lymphopenia had been proved to be a robust predictor in different models across the board. Kaplan–Meier analysis showed significant inferior survival of T-lymphopenia patients in both derivation and validation cohort. The adverse prognosis of T-lymphopenia was also confirmed among disease entities such as SLE and MDA5 + DM. In addition, T-lymphopenia patients needed more invasive procedures and had a significantly higher ICU acquired infection rate. T-lymphopenia was proven to be a simple but strong prognostic predictor for 28-day mortality and more severe diseases in a unique Rh-ICU cohort, which may help to improve the management of critically ill SARDs.