All-Cause and Exacerbation-Related Readmissions in Thrombotic Microangiopathy Requiring Plasmapheresis: A Population-Based Cohort Study

Objective: Thrombotic microangiopathy (TMA) is a serious condition characterized by microangiopathic hemolytic anemia and thrombocytopenia, with high exacerbation rates. This study examined all-cause and exacerbation-related readmission risks among patients hospitalized with TMA requiring plasmapheresis. Materials and Methods: Secondary analysis of the 2020 Nationwide Readmission Database was conducted, including discharge data from non-federal hospitals in 31 U.S. states. Patients aged 18 years or older admitted non-electively with a primary or secondary diagnosis of TMA requiring plasmapheresis were included. Exacerbation-related readmission was defined as subsequent admission requiring plasmapheresis within 7 or 30 days after the original discharge. Multivariable logistic regression and Cox proportional hazards models were used to assess readmission risks, adjusting for demographics, comorbidities, and predisposing factors. Results: Among an estimated 1393 patients, 791 (56.8%) had predisposing conditions. All-cause readmissions were more frequent in patients with predisposing conditions (26.2% vs. 21.9%), while exacerbation-related readmissions were more common in TMA-only patients (9.0% vs. 3.4% at 7 days; 13.7% vs. 6.4% at 30 days). Most exacerbations occurred within 14 days after discharge. No patients treated with caplacizumab experienced exacerbation. TMA-only patients had a 2.1-times higher risk of 30-day exacerbation-related readmissions (adjusted hazard ratio: 2.10, p=0.04). Rural residence and patient-directed discharge were potential risk factors for exacerbation-related readmissions. Conclusions: These findings highlight the need for improved post-discharge care and treatment strategies to prevent readmissions. Further studies should explore interventions to reduce exacerbation-related readmissions, particularly in high-risk populations.