Prognostic factors in Sézary syndrome - a retrospective propensity score-matched study on 1277 patients.

Introduction: Sézary syndrome (SS) is a rare neoplasm associated with poor prognosis. Due to the rarity of the disease, large-scale investigations are scarce, while identifying prognostic factors is essential for improving treatment outcomes. The primary objective was to investigate prognostic factors in a large population of SS patients on survival and infections. The secondary objective was to validate a previously suggested prognostic index model. Methods: We conducted a propensity score-matched retrospective cohort study using real-world data from 1277 patients in the TriNetX database. Risk factors examined included age, elevated lactate dehydrogenase (LDH), anemia, elevated white blood cell count (WBC), sex, and race. Examined outcomes were: 5-year survival, Systemic Inflammatory Response Syndrome (SIRS), sepsis and pneumonia. The prognostic index model was simplified into factors assessable through TriNetX. Results: Age > 60 years, elevated LDH, anemia and elevated WBC were risk factors for 5-year overall survival. Elevated LDH, anemia, elevated WBC and African American/black race were significantly associated with sepsis. Anemia and elevated WBC were also linked to higher risk of pneumonia. Additionally, we devised and validated a simplified prognostic index model (sPIM) accounting for patient focus on SS (stage IV) patients. Conclusion: In the largest group of SS patients assessed for risk stratification to-date, we confirm age and elevated LDH as risk factors in SS and their applicability in the prognostic index model. This study introduces anemia as a novel risk factor and demonstrates the prognostic value of leukocytosis in SS. While race requires further investigation, sex appears to have no significant impact on survival.