Association between metabolic overweight/obesity phenotypes and readmission risk in patients with Immune Thrombocytopenia (ITP): a national retrospective study

Abstract Immune thrombocytopenia (ITP) is one of the most common autoimmune hemorrhagic disorders and is characterized by frequent relapses that require repeated hospitalization. Although overweight/obesity and metabolic disorders have been linked to ITP, their association with readmission risk remains unclear. A cohort of 3,811 patients with a discharge diagnosis of ITP was identified from the National Readmission Database (NRD) for this retrospective analysis. Patients were classified into four phenotypes according to overweight/obesity status and metabolic status: metabolically healthy non-obese (MHNO), metabolically unhealthy non-obese (MUNO), metabolically healthy obese (MHO), and metabolically unhealthy obese (MUO). Readmissions were assessed at 30, 60, 90, 120, 150, and 180 days. Multivariable Cox proportional hazards models were used to evaluate the association between metabolic overweight/obesity phenotypes and readmission risk in this cohort. At 120, 150, and 180 days, patients with metabolically unhealthy phenotypes had a significantly higher risk of readmission than those with the MHNO phenotype. In contrast, the MHO phenotype was not associated with increased readmission risk. Subsequent stratified analyses showed a gradual increase in readmission risk with a higher number of concurrent metabolic risk factors. Among patients with ITP, metabolic disorders, rather than overweight/obesity, were associated with an increased risk of readmission after multivariable adjustment. Readmission risk also increased with the number of concurrent metabolic risk factors. Notably, the association between metabolic comorbidities and ITP-related readmission showed a distinct time-dependent pattern. Because this study did not include a non-ITP control group, whether this association is specific to ITP or reflects a broader effect of metabolic comorbidities on readmission remains uncertain.